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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]

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.

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.

Recombinant glycoprotein 120 (rgp120) of human immunodeficiency virus type-1 (HIV-1) activates the human complement system in the absence of anti-gp120 antibodies. HIV-1 glycoprotein gp120 can dissociate from the viral envelope either spontaneously or after binding of HIV-1 to the CD4 molecule. As a consequence, gp120 can circulate in the patient's serum and attach to the surface of uninfected CD4+ T cells. Complement activation by cell-bound HIV-1 glycoprotein gp120 with subsequent opsonization may represent a mechanism for the elimination of uninfected CD4+ cells by the reticuloendothelial system, thereby enhancing the progression of HIV disease. In the current study, the complement proteins C4,C3,C5,C9, and properdin were found to bind to a synthetic peptide covering positions 233-251 of the gp120BRU sequence on incubation with normal human serum. Complement activation by the peptide was comparable with that induced by aggregated IgG, complete rgp120, and the previously described complement-activating gp41-peptide 609-623. Activation occurred via the classical pathway and was abrogated in the presence of EDTA, Mg2+/EGTA, or C4-deficient human serum. Peptides partly overlapping the sequence 233-251 activated complement to a lesser extent. The complement-activating capacity of the gp120 sequence 233-251 was not restricted to the HIV-1BRU isolate, because a peptide from the corresponding sequence of the HIV-1MN strain was also capable of activating complement. An additional strong complement-activating site was identified in the gp120 sequence 321-360 of the HIV-1MN strain. These data indicate that distinct sites in gp120 are able to activate human serum complement via the classical pathway in the absence of anti-gp120 and independent of glycosylation.

The concept of autoimmune mechanisms playing an integral role in the pathogenesis of HIV disease is rapidly gaining ground. In this study, we determined IgM and IgG antibodies, complement fragments and gp120 on the surface of CD4+ lymphocytes using double-fluorescence flow cytometry. Sequential analysis demonstrated an inverse relationship of autoantibodies and CD4+ lymphocyte counts in the peripheral blood. HIV+ patients without autoantibodies (16/104 = 15%) had the highest CD4+ blood cell counts (324 +/- 264/microliters; mean +/- SD). CD4+ counts were successively lower in patients with complement-fixing IgM (243 +/- 240/microliter), complement-fixing IgG and IgM (139 +/- 138/microliter), or gp120-IgM/IgG complement complexes on the surface of CD4+ cells (38 +/- 45/microliter, P = 0.03). Individual patient profiles show that IgM autoantibodies typically are formed early after HIV infection and appear to deplete CD4+ lymphocytes very slowly, whereas complement-fixing IgG autoantibodies are generated at a later stage and deplete CD4+ lymphocytes more efficiently. The presence of both soluble gp120 and complement-fixing autoantibodies on CD4+ lymphocytes is associated with very low CD4+ cell counts and coincides with progression to terminal disease. Early during HIV infection autoantibody production is rather unstable, but it becomes more stable with disease progression and persists in advanced stages of the disease. These data suggest that autoantibody formation against CD4+ lymphocytes is a pathogenic mechanism for CD4+ cell depletion.

There is increasing evidence that autoimmune phenomena play an important role in the immunopathogenesis of AIDS. We found a high degree of sequence homology between HIV-1 and antigen receptor molecules, immunoglobulins and T cell receptors. Based on recent findings that the appearance of anti-Fab autoantibodies and attachment of gp120/immunoglobulin/complement complexes on CD4+ T cells are associated with the decrease of CD4+ T cells in HIV-infected patients, we hypothesize herein that cross-reactive anti-F (ab')2 autoantibodies and circulating gp120 molecules are responsible for a destabilization of the immune network and the elimination of CD4+ T cells.

In a brief summary the improvements introduced during synthesis of a minigene coding for the peptide hormone angiotensin II are outlined. Furthermore some recent improvements are reviewed: comprehensive study of N-protecting groups for the heterocyclic bases, effective 3'-O-phosphorylation using phosphomonochloridates and molecular sieves, a quick and mild detritylation procedure without any depurination using ZnBr2, a convenient tritylation method using molecular sieves, introduction of a sugar spray reagent for a simpler interpretation of tlc, an improved two-step-one-flask procedure for the synthesis of fully protected triester intermediates, an introduction of new phosphate protecting groups removable by beta-elimination in homogeneous phase, synthesis of the internucleotidic phosphotriester linkage using phosphomonoazolide derivatives of deoxynucleosides, versatile methods for anchoring nucleosides to a polymer support and a computerized nucleic acid synthesizer.