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Objective: Due to increasing waiting times for deceased donor kidneys, living donor kidney transplantation is increasingly performed in the presence of donor-specific antibodies (DSA)., Methods: Twenty-three patients with Luminex-detected DSA were successfully desensitized by anti-CD20 therapy and immunoadsorption (N = 19) or plasmapheresis (N = 4) and received a kidney transplant from a living donor. Twelve of the 23 patients (52%) had a positive CDC and/or ELISA crossmatch result before desensitization. Six patients were negative in CDC as well as ELISA screening but positive in Luminex for DSA., Results: The 23 patients received a median of 8 apheresis treatments before and 5 treatments after transplantation. Induction therapy was performed with either thymoglobulin (N = 11) or basiliximab (N = 12). The 2-year graft survival rate was 100%. At last follow up, a median of 12 months after transplantation, median serum creatinine was 1.42 mg/dL, median MDRD-GFR 59.5 mL/min/1.73 m(2), and median urinary protein-to-creatinine ratio 0.12. Ten out of fourteen patients (71%) who had completed the first year after transplantation by the time of analysis had no DSA by day 360. Acute T-cell mediated rejection was diagnosed in one patient (4%), and antibody-mediated changes were found in 5 patients (22%). Four out of these 5 patients showed evidence of persistent (N = 2) or reemerging plus/minus de novo DSA (N = 2) on day 360, and the 2 patients with persistent DSA lost their allograft subsequently on days 750 and 810, respectively. Infectious complications were infrequent., Conclusions: Our previously described treatment algorithm for desensitization of living donor kidney transplant recipients with DSA results in good graft outcomes with a low rate of side effects., (Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.)

After initiation of highly-active antiretroviral therapy (HAART), long-term HIV-infected hemophilia patients have been shown to lose autoantibodies against CD4(+) peripheral blood leukocytes (PBL), suggesting that HAART induces autoimmunity-blocking mechanisms. We compared cytokine levels and subpopulations of lymphocytes and dendritic cells (DC) in the blood of 40 long-term HIV(+) patients with those of 13 long-term HIV(-) hemophilia patients; 23 HIV(+) patients had a detectable retroviral load. Cell subsets were determined using flow cytometry and cytokine levels were measured using ELISA. HIV(+) patients showed higher proportions of DC subpopulations with immunostimulatory phenotypes (p < 0.01), CD8(+) PBL (p < 0.001), and IL-2 (p < 0.001) and sIL-2R plasma levels (p = 0.002) than HIV(-) patients. They also exhibited increased proportions of T PBL with immunosuppressive phenotypes such as CD3(+)CD4(+)CD25(+)Foxp3(+) (p = 0.001), and CD3(+)CD8(+)CD28(-)Foxp3(+) PBL (p < 0.001), and a decreased IL-7R expression on CD3(+)CD8(+) PBL (p = 0.001) compared to HIV(-) patients. Frequencies of CD3(+)CD4(+)CD25(+) PBL producing IL-2, IL-4, IL-10, IL-12, and/or IFN-gamma, and of CD3(+)CD4(+)CD28(-) PBL secreting IL-2 and/or IL-4 were lower in HIV(+) than in HIV(-) patients (p

Background: Adverse events occurring early after kidney transplantation were reported to influence graft outcome., Methods: In a prospective multicenter study initiated in 2001, we investigated the relationship between human leukocyte antigen (HLA) alloantibodies, early adverse events, and graft outcome., Results: Pretransplant presence of HLA class I antibodies was associated with a higher rate of no immediate function (NIF) of the graft (odds ratio [OR] 1.78, P=0.023) and acute rejection episodes (ARE) during the first 3 months after transplantation (OR 2.53, P<0.001). NIF and ARE during posttransplant days 15 to 90 were associated with increased risk of graft loss to year 3 (OR 2.06 and 3.75, P=0.006 and P<0.001, respectively). ARE within the first 2 posttransplant weeks did not increase the risk significantly, especially if they occurred in nonsensitized patients without antibodies. Graft survival at 3 years in patients with both NIF and ARE during the first 3 months was significantly lower (81.3%+/-6.2%) than in patients who did not experience NIF or ARE (95.1%+/-1.0%, P<0.001). Importantly, neither NIF nor ARE had an impact on subsequent graft survival if good graft function (serum creatinine <130 mumol/L) was observed at the end of the third month., Conclusion: Our results show that NIF and ARE associated with pretransplant antibodies against HLA class I, and they suggest that early diagnosis and treatment of adverse events with the aim of obtaining normal 3-month graft function should be pursued rigorously. Good 3-month graft function is associated with excellent long-term survival, even in patients with pretransplant HLA antibodies and posttransplant adverse events.

It is believed that autoimmune phenomena and apoptosis contribute to CD4 depletion. We investigated 11 long-term (>20 years) HIV-infected haemophilia patients and 10 healthy controls. Using four-colour-fluorescence flow cytometry, we studied the proportions of CD3+CD4+ and CD3+CD4- blood lymphocytes that were CD95+, CD95L+, immune complex+ (IC+, consisting of IgM, IgG, C3d and/or gp120), and were viable or non-viable (propidium iodide+ = PI+). In addition, we studied viability of CD4+IgG+ patient lymphocytes using the apoptosis marker annexin and the permeability indicator 7-amino actinomycin D (7-AAD). HIV+ patients had a higher proportion of CD3+CD4+IgG+PI+ lymphocytes than healthy controls (median: 3.7%versus 0.3%; P = 0.00001). These non-viable IgG-coated lymphocytes might have been killed in vivo by ADCC or complement lysis; 9.1% of the circulating CD3+CD4+ blood lymphocytes were IgG+PI- (controls: 2.5%; P = 0.001). These viable IgG-coated lymphocytes might be targets for phagocytosis or anti-CD95 autoantibody-mediated apoptosis. Because HIV+ patients and healthy controls had similar proportions of PI+ or PI- CD3+CD4+ lymphocytes that carried CD95L on the surface, and because CD3+CD4+CD95L+ cells that were IgG+, C3d+ and/or gp120- were increased in HIV+ patients, the role of CD95L-induced apoptosis in long-term HIV-infected haemophilia patients remains unclear. The findings that HIV+ patients had higher proportions of CD3+CD4+CD95+ (PI+: 6.5%versus 1.4%; P = 0.00002; PI-: 55.8%versus 44.4%; P = 0.04) blood lymphocytes and that the proportion of CD4+IgG+Annexin+7-AAD- blood lymphocytes was associated inversely with peripheral CD4 counts (r = -0.636; P < 0.05) suggest that attachment of IgG to CD4+ blood lymphocytes (anti-CD95?) induces in some lymphocytes apoptosis with subsequent depletion of these IgG-coated apoptotic CD4+ lymphocytes from the circulation. We found supporting evidence for the contention that autoantibody-induced apoptotic and non-apoptotic mechanisms contribute to CD4 depletion in long-term HIV-infected haemophilia patients.

Anti-immunoglobulin autoantibodies (anti-Ig auto-Abs) are part of the physiological immune repertoire. Herein we focus on Abs directed against the F(ab')2 region of the Ig molecule. The vast majority of previously described anti-F(ab')2 auto-Abs were antiidiotypes. The antibodies we studied recognize epitopes located in the hinge region of IgG and in other conserved domains of F(ab')2. Gene structure analyses revealed germline gene identity of VL chains and 88% homology with the closest germline gene of VH chains. We present evidence for a B cell suppressive role of anti-Ig Abs and discuss the mechanism of suppression. Moreover, the role of anti-Ig auto-Abs in immunoregulation as well as in the pathogenesis of autoimmune and other diseases is discussed. There is substantial evidence indicating that anti-Ig auto-Abs are important immunoregulatory molecules.

Pentachlorophenol (PCP), hexachlorocyclohexane-[alpha], -beta, and -[gamma] (HCH-[alpha], -beta, and -[gamma]), polychlorinated biphenyls (PCBs), and hexachlorobenzene (HCB) are widely distributed industrial chemicals. They are suspected to induce immunologic impairments in exposed individuals. We examined dose-response relationships of blood levels of these chemicals with cellular (numbers of lymphocyte subpopulations, in vitro lymphocyte response) or humoral (plasma cytokine levels, immunoglobulin autoantibodies) immunologic dysfunctions. We studied 146 patients who had been occupationally exposed primarily to PCBs for more than 6 months. Lymphocyte subpopulations, in vitro responses to mitogens and allogeneic stimulator cells, plasma neopterin, cytokines, soluble cytokine receptors, soluble adhesion molecules, anti-Ig autoantibodies, and liver transaminases were determined. Blood levels of the different compounds were strongly correlated with one another. There were only weak dose-response relationships between blood levels of PCBs with cellular immune parameters, and of HCHs and HCB with humoral immune parameters. An exception was the statistically significant negative association of HCB with interferon-[gamma] (IFN-[gamma]), indicating that HCB has a significant impact on Th1 lymphocytes. Patients with HCB blood levels above the mean of 1,109 ng/L more often had undetectable IFN-[gamma] blood levels than patients below the mean. Patients with increased PCB 138 (> 710 ng/L) had more frequently undetectable interleukin-4 blood levels than patients with PCB 138 below the mean, and patients with increased PCB 101 (> 31 ng/L) more often had low DR+ cell counts in the blood (< 190/microL) than patients with PCB 101 below the mean. To assess possible cumulative effects, we compared patients who had blood levels of all compounds below background with patients who had blood levels of all compounds above background. Patients with low or absent blood levels of the compounds studied had higher IFN-[gamma] plasma levels, providing some evidence for a cumulative effect of several weakly active compounds. In conclusion, exposure to PCBs, HCB, or HCHs is associated with weak immunologic abnormalities. These results contrast with those obtained in earlier studies of blood levels of PCP, which showed a strong dose-dependent relationship with immunologic impairments. Our data suggest that long-term exposure of patients to HCB suppresses IFN-[gamma] production.

Background: Preliminary studies showed an excellent success rate of kidney grafts in patients with high pretransplantation serum levels of IgA autoantibodies directed against the Fab region of the human IgG molecule., Methods: With the collaboration of 30 centers from around the world, we attempted to verify the role of IgA-anti-Fab autoantibodies in kidney transplantation in an entirely new series of 4316 cadaveric kidney transplants, with special consideration of presensitized and poorly HLA-matched recipients., Results: In agreement with previously published preliminary findings, 147 recipients with a high pretransplantation IgA-anti-Fab of >1000 had a 2-year kidney graft survival rate of 88+/-3% (+/- SE), compared with an 80+/-1% rate in 851 recipients with a low IgA-anti-Fab of <60 (P = 0.02). Even in patients at an increased risk of graft rejection, high pretransplantation IgA-anti-Fab autoantibody activity was associated with superior graft survival. Among 815 presensitized patients, 31 had a high pretransplantation IgA-anti-Fab activity of >1000 and their 2-year graft survival rate was 94+/-4%, in contrast to a 71+/-4% rate in 165 presensitized recipients with a low IgA-anti-Fab of <60 (P = 0.02). Of 2294 recipients who received a kidney with > or =3 HLA-A+B+DR mismatches, 79 recipients had a high pretransplantation IgA-anti-Fab of >1000 and a 2-year graft survival rate of 90+/-4%, as compared with a 79+/-2% rate in 459 patients with a low IgA-anti-Fab of <60 (P = 0.04)., Conclusions: The present study confirms that kidney graft recipients with high pretransplantation IgA-anti-Fab activity have excellent graft survival, and it extends this observation to presensitized recipients and poor HLA matches.

It has been known for a long time that IgG-anti-F(ab')(2) antibodies (Abs) are able to suppress the B-cell response. We showed that natural IgG-anti-F(ab')(2) autoantibodies appear in the serum of patients with cold agglutination. If the anti-F(ab')2 Ab suppresses cold agglutinin (CA)-producing B cells, one would expect an inverse correlation between the titers of these two Abs. Our study confirmed this correlation. Subsequent experiments showed that some anti-F(ab')(2) Abs bind to the hinge region of IgG. It was difficult to explain how this Ab suppresses CA-producing B cells, which are of IgM isotype. Here we show that patients with cold agglutination have an IgG-anti-kappa light chain autoantibody in their serum. This is another member of the anti-F(ab')(2) Ab group. Because the vast majority of CAs are IgM-kappa Abs, the anti-kappa Ab might suppress CA-producing B cells. If this is the case, there should be an inverse association between the titer of anti-kappa Ab and CA. In a group of 302 patients, we found that high titers of the anti-kappa Ab correlate with low titers of CA and vice versa (P =.009). Interestingly, this association is found only in patients whose disease is caused by noninfectious agents, including mainly B-cell proliferations (P =.0058). Our data show that the inverse correlation is not confined to a particular CA autoantibody specificity. The results are discussed in the light of recent findings showing that anti-IgM Abs may either inactivate or kill tumoral B cells by apoptosis.

Background and Objectives: Human immunodeficiency virus (HIV)-induced immune complex load on circulating CD4+ blood lymphocytes is associated with dysfunction and depletion of CD4+ lymphocytes and with increased monocyte/macrophage function. It was investigated whether HAART reduces both the viral load in plasma and the number of immune complex-coated CD4+ lymphocytes in the blood, and whether CD4+ counts are associated with viral load and/or immune complex load., Materials and Methods: Twelve HIV+ hemophilia patients before and after conversion to HAART (group 1); eight HIV+ hemophilia patients without antiretroviral therapy (group 2). HIV-1 RNA copies in plasma using NASBA/Nuclisens kits; CD4+ lymphocytes coated in-vivo with immune complexes using flowcytometry on whole blood samples; in-vitro responses of immune complex-coated T lymphocytes in cell culture assays., Results: After conversion to HAART there was a significant reduction of viral load, CD4+ gp120+, CD4+ IgM+, and CD4+ IgG+ circulating blood lymphocytes and plasma neopterin, paralleled by a significant increase of CD4+ and CD8+ counts. The percentage of immune complex-coated CD4+ lymphocytes of converted patients was significantly associated with CD4+ counts, in-vitro responses to concanavalin A (Con A), pokeweed mitogen (PWM), phytohaemagglutinin (PHA), anti-CD3 and pooled allogeneic stimulator cells, and with plasma neopterin levels., Conclusion: HAART reduces viral load and HIV-induced immune complex load on circulating CD4+ blood lymphocytes. The results of this study can be interpreted to suggest that HAART increases CD4+ lymphocyte counts in part by counteracting HIV-induced autoimmune phenomena.

Anti-immunoglobulin autoantibodies (anti-Ig auto-Abs), particularly IgM-anti-IgG (classical rheumatoid factor), have been studied mainly in the context of rheumatoid arthritis. In this article we focus on other members of the anti-Ig family, including the natural IgG-anti-F(ab')2 auto-Ab, and look for clinical and experimental findings supporting a role of these antibodies in the regulation of the immune response. We discuss the evidence for suppression of auto- and alloreactive B cells by IgG-anti-F(ab')2 auto-Ab and the role of this Ab in the pathogenesis of certain diseases, such as autoimmune hemolytic anemia. The structure of the antibody's antigen-binding site was clarified by isolating the VL and VH gene segments from the cDNA of B cells. Sequence analyses revealed germline gene identity of VL chains and 88% homology with the closest germline gene of VH chains. Finally, we discuss hypothetical models concerning the immunoregulatory role of natural anti-Ig auto-Abs.

Objective: We investigated whether the induction of antilymphocyte autoantibodies and immune complexes is associated with the activity of HIV replication., Methods: Viral HIV-1 RNA was measured in the plasma samples of 84 HIV+ hemophilia patients and correlated with the IgM, IgG, IgM/IgG and IgM/IgG/gp120 load of circulating CD4+ lymphocytes, CD4+ and CD8+ cell counts, plasma neopterin levels and in vitro T-cell responses to mitogens and pooled allogeneic stimulator cells., Results: Compared to patients with no immune complexes, on circulating CD4+ lymphocytes, viral load was increased in patients with IgM, IgM/IgG or IgM/IgG/gp120 complexes. Sequential analysis of HIV+ patients showed that peaks of retroviral activity were associated with the subsequent formation of CD4+ lymphocyte-reactive IgM and IgG autoantibodies and gp120-containing immune complexes., Conclusion: The induction of autoantibodies and immune complexes attached to CD4+ lymphocytes is associated with periods of increased viral activity in HIV-infected patients.

To analyse CD4 cell cytokine secretion and helper/suppressor function at a clonal level we established 446 CD4+ T cell clones (TCC) in four healthy controls, three HIV- haemophilia patients, four CDC II,III and four CDC IV patients. Spontaneous TCC secretion of Th1 cytokines (IL-2, interferon-gamma (IFN-gamma)) and Th2 cytokines (IL-4, IL-6, IL-10) was determined by ELISA. TCC helper and suppressor functions were tested in a pokeweed mitogen (PWM)-stimulated allogeneic co-culture system using a reverse haemolytic plaque assay for assessment of B cell responses. There was a significant association of TCC surface marker expression (Leu-8, CD45RA) with TCC IL-6 secretion in healthy controls (P < 0.01), HIV- patients (P < or = 0.001) and CDC II,III patients (P < or = 0.01) but not in CDC IV patients. Likewise, TCC expression of Leu-8 and CD45RA was significantly associated with TCC suppressor function in healthy controls (P < or = 0.0005) but not in HIV-infected patients. A reduced TCC helper frequency (< or = 10% of TCC) and an enhanced TCC suppressor frequency (> 80% of TCC) were detected only in those HIV-infected patients who showed an excessively increased TCC IL-6 secretion (> 70% of TCC) together with a significantly diminished TCC IL-10 secretion (< or = 10% of TCC). CD4 cell autoantibodies also were found only in patients with this type of cytokine dysregulation. These data indicate that CD4 cell surface markers lose their functional relevance in HIV-infected patients. HIV-induced IL-6/IL-10 dysregulation of CD4+ T cells, i.e. the up-regulation of spontaneous IL-6 and down-regulation of spontaneous IL-10 secretion, appears to be involved in inducing CD4 helper defects and may promote autoantibody formation against CD4 cells.

Previous reports provided evidence of an immunosuppressive role of natural anti-F(ab')2 antibodies. If suppressive anti-F(ab')2 antibodies also regulated the autoantibody production in cold agglutination, one would expect high titers of anti-F(ab')2 to be associated with low titers of cold agglutinins. Indeed, our previous studies revealed an inverse correlation between IgG-anti-F(ab')2 and cold agglutinins. Many previous experiments focused on anti-F(ab')2 of an antiidiotypic nature. Recent epitope mapping showed that anti-F(ab')2 of healthy persons is not an antiidiotype but recognizes a hinge region sequence. We attempted to answer the question whether this IgG-antihinge antibody is responsible for the previously described association between anti-F(ab')2 and cold agglutinins. IgG-antihinge and IgG-anti-F(ab')2 antibody was determined and statistically analyzed in the serum of 334 patients with cold agglutination. Our experiments revealed a strong correlation between the concentrations of antihinge and the previously described anti-F(ab')2 antibody. The anti-F(ab')2 activity was competitively inhibited by a synthetic hinge peptide. Moreover, patients with high antihinge titers had low cold agglutinin titers, and vice versa. A stratification according to cold agglutinin specificity and disease etiology showed that the inverse correlation is present only in anti-I and anti-i patients suffering from monoclonal B-lymphocyte proliferation. In conclusion, our results confirm the correlation previously described for anti-F(ab')2 antibody and antierythrocyte autoantibody and define for the first time an association between an idiotype-independent anti-IgG autoantibody and cold agglutinin.

Recent studies revealed an immunoregulatory role of natural IgG-anti-F(ab')2 antibodies in both healthy individuals and patients with certain diseases. The implication of anti-F(ab')2 antibodies in the pathogenesis of diseases prompted us to study the gene segment structure of their antigen-binding domains and their binding characteristics. cDNA was prepared from the lymphocytes of a patient with a high IgG-anti-F(ab')2 serum titer. Variable heavy and light gene segments were amplified by PCR and inserted into a phagemid surface expression vector. Single-chain antibodies displayed on the phage surface were screened for binding to F(ab')2 fragments. The subsequent analysis of 95 single clones demonstrated that they all bound specifically to F(ab')2. Sequence analyses of 12 clones showed that 11 were identical and 1 contained a silent point mutation in the heavy chain and three amino acid exchanges in the light chain. The heavy chains belonged to the V(H)3 and the light chains to the V(kappa)2 gene family. The 11 identical light-chain genes were completely homologous to a germ-line sequence (DPK-15). Binding assays showed that the single-chain antibodies bind to F(ab')2, but not to Fab, Fc, or intact IgG. This binding pattern was confirmed by surface plasmon resonance studies, which revealed a relatively high affinity (Ka = 2.8 x 10(7) M(-1)). The strong binding capacity was further demonstrated by competitive inhibition of the serum anti-IgG antibody's interaction with antigen. The present study defines for the first time to our knowledge the gene segment structure of the antigen-binding domain of two human IgG-anti-F(ab')2 autoantibody clones and describes the binding kinetics of the purified monomeric fragments.

Background: Patients with malignant tumors of the head and neck often show immune defects. Increased serum IgA levels have been reported in these groups of patients. We investigated whether IgA-anti-Fab or IgA-anti-F(ab')2 autoantibodies, which have been shown to correlate with severe dysfunction of the immune system, also appear in patients with head and neck cancer., Patients: Sera of 110 patients with squamous cell carcinoma, eight patients with adenoid cystic carcinoma, and 57 healthy controls were tested with an ELISA for IgA-anti-Fab autoantibody activity., Results: Patients with head and neck cancer showed a higher IgA-anti-Fab activity (OD:399, n = 118) than healthy controls (OD: 84, n = 57, p < 0.0001). An association between stage of disease and IgA-anti-Fab activity could be established in patients with SCCHN. Stage IV patients had a significantly higher IgA-anti-Fab activity (OD: 538, n = 51) than stage 1 patients (OD: 283, n = 18, p < 0.05). Patients with stage II (OD: 293, n = 13) or stage III (OD: 379, n = 28) showed intermediate activity. Also a higher IgA-anti-Fab activity than in healthy controls was demonstrated in the eight patients with ACCHN (OD: 314, n = 8, p < 0.01). The highest IgA-anti-Fab activity was observed in eight patients with SCCHN who died within six months after testing (OD: 1004, n = 8). Similar results were obtained for IgA-anti-F(ab')2 autoantibodies. Our findings suggest an association between autoimmunity and final desintegration of physiological body functions., Conclusions: The occurrence of IgA-anti-Fab/IgA-anti-F(ab')2 autoantibodies might be interpreted as an aspect of immune deficiency in patients with malignant tumors of the head and neck.

Natural anti-IgG autoantibodies are found both in healthy individuals and in patients with certain diseases. One group of these Abs recognizes epitopes located in the F(ab')2 region of the IgG molecule. The immunoregulatory role of these Abs in healthy individuals, graft rejection, and disease was previously studied, usually with a focus on the characterization of anti-idiotypic Abs. In the present study, we characterize the epitope recognized by an anti-F(ab')2gamma autoantibody of the IgA isotype, which occurs in the serum of healthy individuals and kidney transplant recipients. The autoantibody described herein reacts strongly with F(ab')2gamma but only poorly with Fab(gamma) fragments, a binding pattern pointing to an epitope located in the hinge region. Using synthetic peptides, we identified a conformational epitope that overlaps the middle and part of the lower hinge region. Structural analyses of peptide constructs showed that a defined conformation of the first three residues of the lower hinge is required for a full expression of the epitope. Binding of IgA to the hinge region of IgG1 covers part of the physiologically active Fc domain, immobilizes the Fab arms, and thereby can be expected to exert immunoregulatory functions.

HIV induces progressive dysfunction followed by numerical depletion of CD4+ lymphocytes. IgG autoantibodies and gp 120-containing immune complexes have been implicated in the pathogenesis of AIDS. We carried out a longitudinal study in 19 HIV- and 72 HIV+ haemophilia patients over a 10-year period in order to investigate a possible relationship between the occurrence of autoantibodies and CD4+ lymphocyte changes. IgM, IgG, C3d and gp120 on the surface of CD4+ lymphocytes were determined in heparinized whole blood with flow cytometry and double-fluorescence. The in vitro response of autoantibody-coated cells was tested in cell cultures with concanavalin A (Con A), phytohaemagglutinin (PHA), pokeweed mitogen (PWM) anti-CD3 MoAb or pooled allogeneic stimulator cells (MLC). After a 10-year follow up, 12 of 71 HIV+ and 16 of 19 HIV- haemophilia patients showed no evidence of immunoglobulins on circulating CD4+ lymphocytes. HIV- haemophilia patients without autoantibodies had CD4+ and CD8+ cell counts in the normal range (957+/-642/microliters and 636+/-405/microliters) and normal T cell responses in vitro (mean relative response (RR) > or = 0.7). In contrast, HIV+ haemophilia patients showed immunological abnormalities which were associated with the autoantibody and immune complex load of CD4+ blood lymphocytes. HIV+ patients without autoantibodies had a mean CD4+ lymphocyte count of 372+/-274/microliter, a mean CD8+ lymphocyte count of 737+/-435 microliter, and normal T lymphocyte stimulation in vitro (mean RR > or = 0.7). HIV+ patients with complement-fixing IgM on CD4+ lymphocytes had somewhat lower CD4+ (255+/-246/microliters, P = NS) and CD8+ (706 +/- 468/microliters, P = NS) lymphocyte numbers, and also normal T lymphocyte stimulation (mean RR > or = 0.7) in vitro. However, patients with complement-fixing IgG autoantibodies showed a strong decrease of CD4+ (150 +/- 146/microliters, P< 0.02) and CD8+ (360 +/- 300 microliters, (P<0.02) lymphocytes and impaired CD4+ lymphocyte stimulation in vitro with a mean RR of 0.5+/-0.5 for Con A (P = NS), 0.7 +/- 0.8 for PHA (P<0.03), 0.4 +/- 0.4 for PWM (P = NS), 0.8 +/- 1.2 for anti-CD3 MoAb (P<0.04) and 0.7 +/- 1.0 for pooled allogeneic stimulator cells (P=0.05). Patients with gp120-containing immune complexes on CD4+ blood lymphocytes demonstrated strongly decreased CD4+ (25+/-35/microliters, P<0.0001) and CD8+ (213+/-212/microliters, P<0.006) lymphocyte counts as well as strongly impaired T lymphocyte responses in vitro upon stimulation with PHA (RR 0.2+/-0.1, P<0.02), PWM (RR 0.2+/&#95;0.2, P=0.05), anti-CD3 MoAb(RR 0.1+/-0.1, P<0.04), and allogeneic stimulator cells (RR 0.2+/-0.1, P<0.02). These data led us to speculate that autoantibody formation against CD4+ lymphocytes is an important mechanism in the pathogenesis of AIDS. We hypothesize that autoantibodies against circulating CD4+ lymphocytes inhibit CD4+ cell function, especially the release of cytokines, and induce CD4+ cell depletion. The reduction and dysfunction of CD4+ lymphocytes may be responsible for the CD8+ cell depletion observed in HIV+ patients.

HIV+ patients form autoantibodies against CD4+ and CD8+ lymphocytes. It was shown that anti-CD4+ lymphocyte autoantibodies are associated with the depletion of CD4+ cells. In the present study we analyzed the relationship of anti-CD4+ and anti-CD8+ autoantibodies with the CD8+ lymphocyte decrease commonly observed during HIV disease. IgM and IgG antibodies as well as complement fragments were determined on the surface of CD4+ and CD8+ lymphocytes using double fluorescence flow cytometry. Anti-CD8+ lymphocyte autoantibodies were found more often in HIV + hemophilia patients (75/105 = 71%) than HIV- hemophilia patients (13/37 = 35%; p < 0.0001), patients with pharyngeal carcinoma (20/44 = 45%; P = 0.002), habitual abortions (3/13 = 23%; p = 0.0009) or healthy individuals (93-223 = 42%; p < 0.0001). Anti-CD8+ antibodies, mostly of the IgM type, occurred significantly more frequently than anti-CD4+ antibodies in healthy controls (p < 0.0001), patients with pharyngeal carcinoma (p = 0.0001), or HIV- patients (p = 0.01). In HIV+ patients, however, anti-CD4+ autoantibodies were found more often than anti-CD8+ antibodies (85 vs 71%; p = 0.02). 70 of 104 (67%) HIV+ patients had autoantibodies on both CD4+ and CD8+ lymphocytes and the IgG/IgM/C3d autoantibody pattern was identical in 31 (44%) of the patients. Interestingly, peripheral blood CD8+ cell counts were significantly associated with anti-CD4+ (p = 0.01) but not with anti-CD8+ lymphocyte autoantibodies. It is hypothesized that the inhibition and depletion of CD4+ cells by anti-CD4+ autoantibodies is associated with a loss of regulatory functions that leads to a depletion of antiviral cytotoxic CD8+ lymphocytes.

HIV-infected patients exhibit defects in B cell differentiation and in the IL-6 response of B cells, in association with autoantibody formation against T cells. These autoantibodies have been implicated as important factors in the development of immunodeficiency disease. As the restoration of defective B cell responses might prevent autoantibody formation and the resulting immunosuppression, we studied whether in vitro treatment with recombinant IL-2 (rIL-2), recombinant IL-4 (rIL-4) or recombinant IL-6 (rIL-6) might restore the response of B cells of HIV-infected patients. B cells of 6 HIV-negative hemophilia patients, 4 HIV-positive patients at CDC stage II, III, 4 HIV-positive patients at CDC stage IV, and 6 healthy controls were tested in Staphylococcus aureus Cowan I (SAC-I)-stimulated B cell cultures and Pokeweed mitogen (PWM)-stimulated allogeneic B and T cell cocultures. B cell differentiation was assessed in a reverse hemolytic plaque assay and by ELISA determination of IgM, IgG and IL-6 in culture supernatants. In vitro application of rIL-6 resulted in suppression of both elevated unstimulated and mitogen-stimulated B cell responses in a dose-dependent manner which was in part due to feedback inhibition. PWM- and SAC-I-stimulated IgG and IgM responses, respectively, could be restored after addition of 10 U/ml rIL-2 in HIV-negative patients, but not in HIV-positive patients. Addition of rIL-4 to cultures resulted in suppression of both unstimulated and mitogen-stimulated IL-6 secretion and B cell responses. Severely depressed B cell responses in CDC IV patients were not significantly affected by cytokine application. These results indicate that defective Ig responses in HIV-negative patients may be restored by rIL-2 treatment whereas HIV-induced B cell defects are not corrected by supply of T cell help or cytokines promoting B cell growth and differentiation.

Two types of antibodies which previously were found to be inversely associated with CD4+ cell counts and which may contribute to the progression of HIV disease were measured in parallel in 55 serum samples of 7 longitudinally tested HIV-infected patients (4 homosexual men, 3 haemophilic men) and in 15 serum samples from 15 patients with advanced AIDS. HIV-infection enhancing antibodies were determined in the presence of near-physiologic human complement concentration using a complement receptor type 2 (CR2) carrying HIV-target cell line. IgG and IgA class autoantibodies directed against human IgG-Fab fragments were measured in specific ELISA assays. In agreement with our previous studies obtained in HIV-seropositive haemophilic patients, significant negative correlations were found between CD4+ cell counts and IgG anti-Fab and IgA anti-Fab antibodies (Spearman correlation coefficient r = -0.587, P < 0.0001; and r = -0.269, P = 0.024, respectively). A significant positive correlation was observed between complement-dependent enhancing antibodies and IgA anti-Fab antibodies (r = 0.408, P = 0.003), whereas the correlation with IgG anti-Fab antibodies was only weak (r = 0.288, P = 0.034). Serum samples with high titres of complement-dependent enhancing antibodies had almost 3 times higher IgA anti-Fab autoantibody activity than sera with low titres (P = 0.0038). Our findings indicate that the two disease markers in HIV disease, enhancing antibodies and autoantibodies directed against the Fab moiety of IgG, are not identical. However, anti-Fab antibodies may contribute to complement-dependent HIV infection enhancement.

Patients with head-and-neck cancer commonly have immune defects. It was reported that these patients have raised serum IgA levels. We investigated whether IgA-anti-Fab autoantibodies, which occur in association with immune dysfunction, are present in patients with head-and-neck cancer. Sera of 101 patients with squamous-cell carcinoma (SCCHN) and 8 patients with adenoid cystic carcinoma (ACCHN) of the head and neck were tested in ELISA for IgA-anti-Fab autoantibody activity. IgA-anti-Fab serum activity was significantly higher in both SCCHN and ACCHN patients than in healthy controls. In patients with SCCHN, an association between disease stage and IgA-anti-Fab activity was established. Stage-IV patients had significantly higher IgA-anti-Fab than stage-I patients or healthy controls. Stage-II and stage-III patients had intermediate levels. Extremely high IgA-anti-Fab activity was observed in 7 patients who died within 6 months following testing, suggesting a relationship of autoimmunity with terminal disintegration of physiological body functions. IgA-anti-Fab autoantibodies may explain the occurrence of immune defects in patients with head-and-neck cancer.

IgA concentration and IgA-anti-Fab autoantibody activity were tested in pretransplant sera of 308 kidney graft recipients. Recipients with a serum IgA concentration of 2 g/l or greater had a 1-year graft survival rate of 83%, compared with a 68% rate in recipients with serum IgA of less than 2 g/l (P < 0.005). Serum IgA concentration and IgA-anti-Fab autoantibody activity were significantly associated (r = 0.38, P < 0.0001). Recipients with a high pretransplant IgA-anti-Fab activity had a significantly better graft survival rate (81%) than patients with low pretransplant IgA-anti-Fab (67%, P < 0.025). When IgA-anti-Fab and serum IgA were considered together, 137 recipients with high IgA-anti-Fab and high serum IgA had a 86% 1-year graft survival rate, which was significantly better than the 63% survival rate in patients with low IgA-anti-Fab and low serum IgA (P < 0.0005). The pretransplant serum IgA level and IgA-anti-Fab autoantibody activity were excellent predictors of kidney graft outcome.

We reported recently that anti-Fab autoantibodies of the IgG isotype are associated with the decrease of helper/inducer (CD4+) lymphocytes in human immunodeficiency virus-infected (HIV+) hemophilia patients with acquired immunodeficiency syndrome (AIDS) or AIDS-related complex (ARC). In the present study we investigated the subclass distribution of IgG-anti-Fab autoantibodies, and whether anti-Fab antibodies of the IgA and IgM isotypes also are associated with the development of AIDS. Sera of HIV+ patients with AIDS had significantly higher IgA-anti-Fab activity than HIV+ patients with ARC (p < 0.02), HIV+ patients without AIDS/ARC (p < 0.0001), HIV-negative (HIV-) patients (p < 0.001), or healthy controls (p < 0.0001). An inverse association was found between IgA-anti-Fab activity and CD4+ cell counts (r = -0.396, p < 10(-6)). In contrast, no association of CD4+ cell counts was observed with IgM-anti-Fab. However, IgM-anti-Fab was significantly increased in patients with thrombocytopenia. We found a significant association between IgA-anti-Fab activity and serum neopterin concentrations (r = 0.310, p < 10(-5)). IgG-anti-Fab activity was detected mainly in the IgG3 fraction, although in HIV+ patients with AIDS/ARC various IgG subclasses were present. Affinity-purified anti-Fab antibodies isolated from sera of AIDS patients bound to rgp120-preincubated CD4+ cells of a healthy individual, supporting our hypothesis that anti-Fab antibodies and free circulating gp120 molecules are involved in the elimination of uninfected CD4+ cells. Removal of anti-Fab autoantibodies from the circulation by immune adsorbance might be a useful approach in the treatment of AIDS.

We showed previously that broadly reactive IgG anti-immunoglobulin autoantibodies produced by rats during the immune response suppress the B cell response. We report here on the effect of a similar human antibody on self-reactive human B cells. IgG anti-F(ab')2 was added to cultures of anti-erythrocyte autoantibody-producing B cells derived from healthy donors. A dose-dependent suppression of the antibody response was obtained (maximum at 1.3 ng IgG/10(6) cells). This effect was competitively inhibited by F(ab')2 gamma. Autoimmune haemolytic anaemia can be caused by chronic monoclonal B cell proliferation. To reproduce this condition in vitro we immortalized B cells with Epstein-Barr virus (EBV) and raised a B cell population with anti-erythrocyte autoantibody activity. These cells were electrically fused with CB-F7 tumour cells and an IgG1 cold-reactive anti-erythrocyte autoantibody-producing B cell line was established. Surprisingly, the tumour cells were not suppressed by IgG anti-F(ab')2. It is known that anti-immunoglobulins selectively suppress antigen-receptor (AgR)-occupied B cells by a Fc gamma-receptor (Fc gamma R)-mediated mechanism. To occupy their AgR, we preincubated the tumour cells with anti-AgR antibody. In spite of this, their susceptibility to suppression was not restored. As shown by rabbit IgG-sensitized ox erythrocyte (EA)-rosetting, this refractoriness was not due to a loss of Fc gamma R. Our experiments delineate a mechanism of peripheral B cell suppression to autoantigens, and show a way of escape from control relevant for the pathogenesis of autoimmune haemolytic anaemia.

There is increasing evidence that autoimmune phenomena contribute to the pathogenesis of the acquired immunodeficiency syndrome (AIDS). We investigated the relationship between IgA autoantibodies directed against the Fab part of the IgG molecule and disease progression in 87 HIV-infected hemophilia patients. AIDS patients demonstrated a significantly higher serum IgA-anti-Fab activity than HIV-positive (HIV+) patients with AIDS-related complex (ARC) (P < 0.02), HIV+ patients without AIDS/ARC (P < 0.0001), HIV negative (HIV-) patients (P = 0.0001), or healthy controls (P < 0.0001). Moreover, an inverse association was observed between serum IgA-anti-Fab activity and CD4+ cell counts (r = -0.396, P < 10(-6)). This close association was confirmed in longitudinal studies of symptomatic patients. IgA-anti-Fab antibodies are suggested to play an important role in the immunopathogenesis of AIDS, and their determination may be helpful in the monitoring of HIV-infected patients.

Immunization of LEW rats with strongly histoincompatible BN blood cells induces, in addition to anti-donor antibody, a broadly reactive IgG autoantibody which binds to IgG and IgM molecules (IgG anti-Ig). Minute amounts of affinity purified IgG anti-Ig (0.2 pg/10(6) cells) suppress the antibody production in vitro of antigen receptor (AgR)-stimulated B cells derived from rats of the same strain. The suppressive antibody is also active in the whole serum IgG fraction. Importantly, anti-Ig-induced suppression is governed by restriction mechanisms: only AgR-occupied B cells are affected, the suppression is cell cycle dependent, and maximum suppression is obtained at an optimum IgG concentration. Treatment of rats in vivo with 0.8 mg Ig-anti-Ig (whole IgG fraction) along with allogeneic cells resulted in nearly complete suppression of the anti-donor antibody response. Possible mechanisms of B cell suppression by IgG anti-Ig are crosslinking of AgR with FcR, or cocapping of the two receptors with sterical interaction as a consequence of their separate occupation. Both alternatives lead to the release of an inactivating signal.

We have shown previously that alloimmunized rats develop a broadly reactive IgG-antiimmunoglobulin autoantibody in addition to antidonor antibodies. The findings presented herein demonstrate that this "physiological" antibody suppresses antigen receptor-induced IgM production of B cells derived from rats of the same strain. When affinity-purified IgG-anti-Ig was added to cell cultures, the antibody production of B cells was maximally inhibited at the minute concentration of 0.9 pg/10(6) cells. Higher or lower IgG-anti-Ig concentrations resulted in weaker suppression. The same result was obtained when spleen lymphocytes were used instead of purified B cells. Based on the molecular weight of IgG and Avogadro's number, our results indicate that a few molecules of IgG-anti-Ig are sufficient to inhibit the antibody production of a single B cell. Activity at this minuscule concentration demonstrates that IgG-anti-Ig antibodies are exquisitely active immunoregulatory molecules. In addition to the stimulatory effect of IgM-anti-Ig rheumatoid factors reported by others, our findings define the second component of an immunoregulatory mechanism: suppression of the B cell response by an IgG-anti-Ig autoantibody produced during alloimmunization.

Heterologous antiimmunoglobulin antibodies are efficient regulators of the B cell response. We have shown that during the immune response against allogeneic cells the immune system develops autologous IgG-antiimmunoglobulin. A few molecules of this "physiological" autoantibody suppress the IgM production of one B cell in vitro. In the current series of experiments we further define the regulation of antigen receptor-activated B cells by this autoantibody. To mimic the in vivo situation, where IgG-anti-Ig appears a few days after alloimmunization, the antibody's effect on an already ongoing B cell response was studied. Interestingly, we found that the IgG-anti-Ig loses its suppressive effect when added to the cell culture 1 or 2 days after B cell activation, but that suppression can be completely restored when the cells are restimulated via their antigen receptor. Thus, the IgG-anti-Ig antibody suppresses B cells only when their antigen receptor is occupied. Even restimulated B cells become refractory 8 hr after activation, and later (24 hr) regain their susceptibility to IgG-anti-Ig-induced suppression. The Fc receptor is involved in mediating suppression since the antibody's suppressive capacity is abolished after removal of its Fc region. Possible mechanisms of B cell suppression by IgG-anti-Ig are crosslinking of antigen receptor with Fc receptor, or cocapping and functional interaction of the two receptors as a result of their separate occupancy. Our experiments demonstrate that B cell regulation by IgG-anti-Ig produced during an immune response to allogeneic cells is governed by 3 restriction mechanisms: antigen receptor occupancy, activation stage dependency, and optimal antibody concentration.

The contribution of autoimmune phenomena to the pathogenesis of acquired immunodeficiency syndrome (AIDS) is poorly understood. We investigated the relationship between IgG-anti-Fab gamma autoantibodies and the main immunologic feature of AIDS, the decrease of CD4+ helper lymphocytes. Sera of 33 human immunodeficiency virus (HIV) infected (HIV+) hemophilia patients with AIDS/AIDS-related complex (ARC), 57 HIV+ patients without AIDS/ARC, 23 HIV-negative (HIV-) patients, and 76 healthy controls were tested for antibody activity against the Fab region of IgG. Patients with AIDS/ARC had significantly higher IgG-anti-Fab gamma activity than HIV+ patients without AIDS/ARC, HIV- patients, or controls (P less than .0001). A striking inverse association was found between IgG-anti-Fab gamma and CD4+ cell counts (r = -.69; P less than 10(-6)). Sequential testing in 16 AIDS/ARC patients showed that an increase in the IgG-anti-Fab gamma activity was invariably accompanied by a decrease in the CD4+ cell count. IgG-anti-Fab gamma antibodies may play an important role in the immunopathogenesis of AIDS.

Our previous studies showed that a broadly reactive immunoglobulin G (IgG) anti-immunoglobulin (IgG-anti-Ig) autoantibody is induced during the immune response of LEW rats to BN blood cells. The present experiments analyze the immunoregulatory effect of this physiological autoantibody on antigen receptor-activated B cells in cell cultures. The results show that: (a) At 0.9 pg IgG-anti-Ig/10(6) B cells, an almost complete suppression of the antibody response is induced: we calculated that a few IgG-anti-Ig molecules are sufficient to suppress the antibody response of one B cell; (b) IgG-anti-Ig-induced B-cell suppression is dose-dependent; (c) IgG-anti-Ig suppresses B cells contained in their natural environment (mixed spleen cell population). These data demonstrate that the IgG-anti-Ig autoantibody is an extremely efficient regulatory molecule of the alloimmune response.

Sera of 76 HIV-negative hemophilia patients, 103 HIV-positive (HIV+) hemophilia patients free of AIDS or AIDS related complex (ARC), and 32 HIV+ hemophilia patients with AIDS/ARC were tested for four different anti-IgG activities. IgG-anti-F(ab')2 gamma, IgM-anti-F(ab')2 gamma, and IgG-anti-Fc gamma serum activities were significantly associated with the clinical stage of HIV infection, whereas IgM-anti-Fc gamma was not. IgG-anti-F(ab')2 gamma activity was found to be caused by cross-reaction of anti-HIV antibody with an epitope within the constant CH1 domain of human IgG. HIV+ hemophilia patients with severe thrombocytopenia (less than 50,000/microliters platelet counts) had significantly higher IgM-anti-IgG activity than patients with greater than 50,000/microliters platelets. Because anti-IgG antibodies possess immunoregulatory properties, our results may serve as a possible explanation for the frequent B cell disorders encountered in HIV-infected patients.

We studied 684 sera obtained from 20 hemophilia patients with AIDS/AIDS-related complex (ARC), 89 asymptomatic HIV+, 76 HIV- hemophilia patients and 151 healthy controls for antibodies against recombinant CD4 (rCD4). Twenty-two percent of AIDS/ARC patients, 10% of asymptomatic HIV+ patients, 17% of HIV-patients, and 1% of healthy controls had anti-rCD4 antibodies. Purified anti-rCD4 antibodies did not react with human CD4+ lymphocytes. This may explain why formation of anti-rCD4 antibodies correlated neither with the occurrence of autoantibodies against CD4+ lymphocytes nor with a decrease in CD4+ cell counts. Antibodies that were eluted from CD4+ lymphocytes after sequential adsorption and elution with separated CD8+ and CD4+ cells reacted with CD4+ lymphocytes of only some healthy individuals, suggesting diversity of CD4 expression.

To investigate whether autoantibodies against CD4-positive lymphocytes might induce helper dysfunction, autoantibody formation and T-cell function was examined simultaneously in 61 hemophilia patients. Twenty patients were human immunodeficiency virus (HIV)-negative, 26 HIV-positive stage CDC II or III, and 15 were HIV-positive stage CDC IV. T lymphocytes, CD4-positive, or CD8-positive T subsets were cocultured with B lymphocytes and pokeweed mitogen (PWM) for 6 days and Ig-secreting cells were assessed in a reverse hemolytic plaque assay. The presence of IgM, IgG, C3d, or gp120 on the surface of T cells or T subsets was analyzed by flow cytometry. Autoantibodies against CD4-positive T cells were not detected in controls or HIV-negative patients, but were common in HIV-positive patients (20 of 41 patients). In patients with autoantibodies we found an increased incidence of CD4 helper defects (P less than .0001 in CDC II or III patients; P less than .02 in CDC IV patients). 12 of 13 patients with IgM autoantibodies and 4 of 4 with IgG autoantibodies showed CD4 helper defects. Complement fixation had no relevance. Autoantibody formation against CD4 cells was not due to increased in vivo B-cell stimulation (spontaneous plaque formation: 611 +/- 204 PFC/10(6) B cells in autoantibody-negative patients v 650 +/- 202 PFC/10(6) B cells in autoantibody-positive patients; not significant). Thus, our results suggest that autoantibody formation is not caused by a general state of in vivo B-cell activation. Rather, the production of autoantibodies appears to coincide with defects in B-cell proliferation or differentiation, as shown by reduced mitogen-stimulated B-cell responses in CDC II and III patients (P less than .05). Autoantibodies against CD4 cells appear to be involved in the pathogenesis of CD4 helper defects of HIV-infected patients.

To demonstrate whether anti-IgG autoantibodies of different isotypes and specificities play a role in kidney transplantation, pretransplant sera of recipients (a) with well-functioning grafts (n = 40); (b) with reversible rejection episodes that were treated successfully (n = 63); and (c) with irreversible graft rejection (n = 40) were tested for four different anti-IgG autoantibody activities. A protective effect of IgG-anti-F(ab)2 gamma antibodies on graft survival was observed (p less than 0.01). High pretransplant IgG-anti-Fc gamma activity was found to be associated with a low kidney graft survival rate (p less than 0.02). Pretransplant IgM-anti-F(ab)2 gamma and IgM-anti-Fc gamma activities showed no effect on kidney graft outcome.

Treatment of LEW rats before transplantation with BN blood cells preincubated with LEW-anti-BN serum resulted in prolonged BN kidney graft survival (untreated, 8 +/- 0.4 days; pretreated, 124 +/- 36). The serum of pretreated animals contains a factor which suppresses T cell proliferation against donor antigens. This effect was not mediated by antiidiotypic antibodies because it was reproduced in a donor-unrelated system. The serum and IgG of pretreated animals also suppressed the humoral immune response. As for T cells, the antibody-suppressive effect was not donor-restricted. A broadly reactive anti-immunoglobulin (anti-B cell) autoantibody was found in the IgG fraction of immunized animals. The mediation of immunosuppression by broadly reactive anti-B and T cell autoantibodies induced by the immunization with antibody-coated blood cells is discussed.

The presence of IgG, IgM, C3d, or gp120 on the surface of T lymphocytes was analyzed by flow cytometry in blood samples from 73 hemophilia patients and 56 healthy controls. IgG and IgM autoantibodies against CD4+ lymphocytes were found in HIV + patients but not in HIV-patients or healthy controls (p less than 0.001). IgM autoantibodies were more frequent than IgG autoantibodies. Autoantibody formation increased with disease progression. However, within the same disease risk category, patients with autoantibodies were not "more immunologically abnormal' than patients without autoantibodies. HIV + patients who possessed autoantibodies had similar CD4+ and CD8+ lymphocyte counts as HIV + patients without autoantibodies. There was no significant difference in the number of patients with abnormal CD4/CD8 ratios, serum neopterin levels, or in vitro responses to allogeneic stimulator cells or mitogens between autoantibody-positive or -negative patients of the same risk category. Our data suggest that autoantibodies against CD4+ lymphocytes may be helpful as indicators of disease progression, however, their immunopathogenetic role remains unclear.

HIV induces progressive dysfunction followed by numerical depletion of CD4+ lymphocytes. IgG autoantibodies and gp120-containing immune complexes have been implicated in the pathogenesis of AIDS. We carried out a longitudinal study in 19 HIV- and 72 HIV+ haemophilia patients over a 10-year period in order to investigate a possible relationship between the occurrence of autoantibodies and CD4+ lymphocyte changes. IgM, IgG, C3d and gp120 on the surface of CD4+ lymphocytes were determined in heparinized whole blood with flow cytometry and double- fluorescence. The in vitro response of autoantibody-coated cells was tested in cell cultures with concanavalin A (Con A), phytohaemagglutinin (PHA), pokeweed mitogen (PWM), anti-CD3 MoAb or pooled allogeneic stimulator cells (MLC). After a 10-year follow up, 12 of 71 HIV+ and 16 of 19 HIV- haemophilia patients showed no evidence of immunoglobulins on circulating CD4+ lymphocytes. HIV haemophilia patients without autoantibodies had CD4+and CD8+ cell counts in the normal range (957 ± 642/0 and 636 ± 405/μl) and normal T cell responses in vitro (mean relative response (RR) &ges; 07). In contrast, HIV+ haemophilia patients showed immunological abnormalities which were associated with the autoantibody and immune complex load of CD4+ blood lymphocytes. HIV+ patients without autoantibodies had a mean CD4+ lymphocyte count of 372 ±274/μl, a mean CD8+ lymphocyte count of 737 ±435/0, and normal T lymphocyte stimulation in vitro (mean RR ) 07). HIV+ patients with complement-fixing IgM on CD4+ lymphocytes had somewhat lower CD4+ (255 ±246/μl, P = NS) and CD8+ (706±468/μl, P = NS) lymphocyte numbers, and also normal T lymphocyte stimulation (mean RR &ges; 0.7) in vitro. However, patients with complement-fixing IgG autoantibodies showed a strong decrease of CD4 + (150± 146/μl, P < 0.2) and CD8 ± (360 ± 300/μl, P < 0.02) lymphocytes and impaired CD4+ lymphocyte stimulation in vitro with a mean RR of 0.5 + 0.5 for Con A (P= NS), 0.7 ± 0.8 for PHA (P < 0.03), 0.4 ± 0.4 for PWM (P = NS), 0.8 ± 1.2 for anti-CD3 MoAb (P < 0.04) and 0.7 ± 1.0 for pooled allogeneic stimulator cells (P < 0.05). Patients with gp120-containing immune complexes on CD4+ blood lymphocytes demonstrated strongly decreased CD4+ (25 ± 35/μl, P< 0.0001) and CD8+ (213 ±212/μl, P< 0.006) lymphocyte counts as well as strongly impaired T lymphocyte responses in vitro upon stimulation with PHA (RR &ges; 0.2 ± 0.1, P < 0.02), PWM (RR 0.2 ± 0.2, P < 0.05), anti-CD3 MoAb (RR 0.1 ±0.1, P < 0.4), and allogeneic stimulator cells (RR 0.2±0.1, P < 0.02). These data led us to speculate that autoantibody formation against CD4+ lymphocytes is an important mechanism in the pathogenesis of AIDS. We hypothesize that autoantibodies against circulating CD4+ lymphocytes inhibit CD4+ cell function, especially the release of cytokines, and induce CD4+ cell depletion. The reduction and dysfunction of CD4+ lymphocytes may be responsible for the CD8+ cell depletion observed in HIV+ patients. [ABSTRACT FROM AUTHOR]

Abstract: We have previously shown that high pretransplant regulatory autoantibodies are associated with better kidney graft outcome. To analyze the effect of intravenous immunoglobulin (IVIG) induction therapy on these regulatory antibodies, we performed a prospective randomized study in 50 renal transplant recipients who were randomly assigned to receive 7 × 10 g IVIG or 7 × 10 g IV albumin infusions. Basic immunosuppressive therapy consisted of tacrolimus/azathioprine (n = 24) and tacrolimus/mycophenolate mofetil (n = 26), respectively. ELISA was used to assess IgG-/IgA-anti-Fab, -anti-F(ab)2 and -anti-hinge regulatory antibodies. IVIG induction therapy resulted in upregulation of serum IgG and IgA levels within the first 20 days posttransplant (P = .001, IgG; P = .04, IgA), so that a significant IgG deficiency was found only in non-IVIG patients (day 10: IgG <6 g/L: 7/25 (28%) non-IVIG versus 0/25 IVIG patients; P = .005). As the IVIG charges contained all of the regulatory antibodies tested, intravenous administration of these antibodies explain the elevated IgG- and IgA-anti-F(ab)2 antibody levels found in IVIG compared to non-IVIG patients on day 10 (P = .005 and P = .04, respectively). Our data indicated that IVIG induction prevented severe IgG deficiency in the early posttransplant period but had no impact on severe infectious complications. IVIG induction enhanced immunoregulatory antibody levels early posttransplant, which might provide graft protective effects. [Copyright &y& Elsevier]