Search

Heterotopic cardiac xenotransplantation from alpha1,3-galactosyltransferase gene-knockout (GalT-KO) swine to baboons was performed to characterize immunological reaction to the xenograft in the absence of anti-Gal antibody-mediated rejection. Eight baboons received heterotopic cardiac xenografts from GalT-KO porcine donors. All baboons were treated with chronic immunosuppressive therapy. Both histological and immunohistochemical studies were performed on biopsy and graftectomy samples. No hyperacute rejection was observed. Three baboons were euthanized or died 16 to 56 days after transplantation. The other five grafts ceased beating between days 59 and 179 (median, 78 days). All failing grafts exhibited thrombotic microangiopathy (TM) with platelet-rich fibrin thrombi in the microvasculature, myocardial ischemia and necrosis, and focal interstitial hemorrhage. TM developed in parallel with increases in immunoglobulin (IgM and IgG) and complement (C3, C4d, and C5b-9) deposition, as well as with subsequent increases in both TUNEL(+) endothelial cell death and procoagulant activation (increased expression of both tissue factor and von Willebrand factor and decreased expression of CD39). CD3(+) T-cell infiltration occurred in all grafts and weakly correlated with the development of TM. In conclusion, although the use of GalT-KO swine donors prevented hyperacute rejection and prolonged graft survival, slowly progressive humoral rejection--probably associated with non-Gal antibodies to the xenograft--and disordered thromboregulation represent major immunological barriers to long-term xenograft survival.

The expression of regulatory proteins tat, rev, and nef of human immunodeficiency virus type-1 (HIV-1) and tat of HIV-2 was studied in frozen sections of lymph nodes from HIV-1-infected individuals, and various tissues from uninfected persons. In HIV-1-positive lymph nodes, monoclonal antibodies to HIV-1-tat stained solitary cells in the germinal centers and interfollicular zones, and vascular endothelium. Staining by an anti-nef monoclonal antibody was restricted to follicular dendritic cells, whereas anti-rev antibody bound to fibriohistiocytes and high endothelial venules. The antibodies used labeled several cell types in tissues from uninfected individuals. Anti-HIV-1-tat antibodies labeled blood vessels and Hassall's corpuscles in skin and thymus; goblet cells in intestinal tissue and trachea; neural cells in brain and spinal cord; and zymogen-producing cells in pancreas. Anti-rev antibody stained high endothelial venules, Hassall's corpuscles and histiocytes. One anti-nef antibody solely stained follicular dendritic cells in spleen, tonsil, lymph node and Peyer's patches, whereas two other anti-nef antibodies bound to astrocytes, solitary cells in the interfollicular zones of lymph nodes, and skin cells. The current results hamper the immunohistochemical study for pathogenetic and diagnostic use of HIV regulatory protein expression in infected tissue specimens or cells.

The expression of 65-kd mycobacterial heat-shock protein (HSP)-related antigens in synovial membrane from rats and humans with arthritis was studied using three monoclonal antibodies and one polyclonal antiserum directed to antigens of mycobacteria. The antibodies labeled synovial tissue sections from both adjuvant arthritis (AA) rats and from patients with either rheumatoid arthritis (RA) or osteoarthritis (OA); especially the synovial lining cells appeared to be positive. The cytoplasmic staining patterns in rats and humans were essentially the same and were not related to the extent of inflammation ie, the size of lymphoid infiltration. In control tissues no cytoplasmic staining was observed. The results suggest a role for a 65-kd HSP or a cross-reactive molecule in the immunopathologic process of arthritic disease.

Follicular dendritic cells (FDC) from axillary lymphoid tissue of a patient with acquired immune deficiency syndrome (AIDS) were analyzed for the presence of gag and env proteins and env mRNA of human immunodeficiency virus type-1 (HIV-1), both in a purified FDC suspension and on frozen sections. Isolated cells with morphologic and immunocytochemical features of FDC expressed HIV-1 core (gag) proteins p15, p17, p24, and envelope (env) protein gp41; in addition HIV-1 env mRNA was detected in some of these cells. This corresponded with intense expression of HIV-1 proteins by FDC in germinal centers in situ, and the presence of HIV-1 mRNA-positive cells in germinal follicles. These findings led us to conclude that FDC are infected and able to produce HIV-1. Such infection may contribute significantly to the destruction of the FDC network during the lymphadenopathy phase after HIV-1 infection.

The authors report an immunohistologic study of primary thymomas from 23 cases with myasthenia gravis (MG) and 7 without. Typical T6+ cortical thymocytes were usually abundant. Most epithelial cells initially appeared to be of cortical type, too, though many bore subcapsular markers in most samples. However, two-color immunofluorescence revealed unexpected heterogeneity, numerous epithelial cells simultaneously expressing some or all of the markers of both these subsets (even in two pleural metastases). It is inferred that there is a common tumor stem cell whose normal counterpart may be related to the rare patches of similar phenotype in the cortex in control samples. The authors could detect no major differences in 5 of 7 samples from nonmyasthenics; thus, most thymoma cases may risk the development of MG. Finally, thymomas from 6 of 7 further MG cases pretreated with corticosteroids showed very few cortical thymocytes, and the (phenotypically similar) epithelium was more obvious.

In a retrospective analysis the authors studied the relation between the immunologic phenotype of B-cell non-Hodgkin's lymphoma (NHL) and disease-free survival. The phenotype included immunoglobulin isotypes; B-cell maturation/differentiation antigens of clusters of differentiation CD9, CD10, CD19-24, CD37, CD38; T-lymphocyte antigens in CD5-7; HLA-DR; peanut agglutinin binding capacity; terminal deoxynucleotidyl transferase; the activation marker CD25 (interleukin-2 receptor); and the proliferation marker transferrin receptor. The phenotype and clinical data were available for 109 patients. Two patients underwent bone marrow transplantation, and 15 patients (with low or intermediate grade NHL) did not receive treatment intended to achieve complete remission. These 17 cases were excluded from the analysis. For individual markers, CD23 expression was associated with a longer actuarial disease-free survival (50% survival in CD23-positive cases was 40 months; and in CD23-negative cases, 16 months; P = 0.01). Among the total study population of 92 patients, this finding applied in particular to those with a low-grade malignancy according to the Kiel classification (P = 0.03). In high-grade NHL (Kiel classification) the absence of CD38 or presence of CD24 on tumor cells correlated with a higher degree of disease-free survival (P values 0.009 and 0.04, respectively). For a combination of five CD markers associated with stages in physiologic B-lymphocyte maturation/differentiation (CD9, CD10, CD21-23), the lowest measure of disease-free survival was observed where NHLs were at an immature stage, and the greatest extent of survival where NHLs were associated with a resting B-cell stage (P = 0.006). These statistical significances aside, the detailed immunologic phenotyping has relatively little prognostic value when compared with that of the malignancy grade assessed by conventional histopathology.

The authors studied thymus specimens taken at autopsy from eight acquired immune deficiency syndrome (AIDS) patients and compared these with those taken from four patients with congenital immunodeficiency (unrelated to an intrinsic thymus defect) and seven patients after allogeneic bone marrow transplantation. In all cases, histology showed a severely involuted architecture, compatible with a debilitating disease before death. There were no major differences between thymus tissue in AIDS patients and in the other patients studied. This argues against the claim expressed in the literature that the epithelial microenvironment incurs particular HIV-1-induced injury in AIDS. This conclusion is substantiated by immunohistochemistry for HIV-1 gag and env proteins, and by hybridohistochemistry for gag/pol and env mRNA of HIV-1. Positive cells were observed only in low numbers, both inside the epithelial parenchyma and in the (expanded) perivascular areas. An interesting finding was the labeling of subcapsular/medullary epithelium in normal uninvoluted thymus by a number of antibodies to HIV-1 gag p17 and p24 proteins. Compatible with this labeling was the staining of epithelial stalks in hyperinvoluted thymuses irrespective of disease category. The previously reported cross-reactivity between HIV-1 core protein and thymosin alpha 1 cannot fully explain this observation, because the epithelium in the hyperinvoluted state is negative for thymosin alpha 1. This study confirms and extends previous reports on the endogenous presence of epitopes of retroviral antigens in thymic epithelium.

The establishment of Clusters of Differentiation for T- and B-lymphoid cells during International Workshops on Human Leukocyte Differentiation Antigens prompted the authors to evaluate the immunophenotypes in 160 cases of non-Hodgkin's lymphoma (NHL). In this group, 130 were of B-lymphocyte lineage (117 by monotypic immunoglobulin expression), and 30 of T-cell lineage. In the B-NHL series the expression of immunoglobulin isotypes, B-cell maturation/differentiation antigens of CD9, CD10, CD19-24, CD37, and CD38 (OKT10), HLA-DR and peanut agglutinin binding showed no significant relationship with histopathologic diagnosis as defined by the Kiel classification. Of the T-cell markers, CD5, CD6, and CD7 showed lineage promiscuity by their presence on some B-NHL. Conversely, the authors grouped the cases according to phenotypes (either CD antigens or immunoglobulin isotypes) which occur in distinct stages of (physiologic) B-cell maturation/differentiation. Eighty-six of the 130 cases could be fitted according to CD phenotype expression. This approach did not yield a significant relationship between phenotype and individual histopathologic categories either. The staging by CD phenotype and by immunoglobulin isotype yielded different results in this respect. Most B-NHL had an intermediate stage of B-cell maturation/differentiation. In the T-NHL series most cases showed a phenotype (CD1-CD8, CD38, TdT, and peanut agglutinin binding capacity) compatible with mature T-lymphocyte characteristics. The exceptions were lymphoblastic convoluted lymphomas, which exhibited an immature immunophenotype. It is concluded that NHL in distinct histopathologic categories are heterogeneous in immunologic phenotypes, and that the immunophenotype of lymphoma cells has no evident association with that of their presumed counterparts in physiologic cell maturation/differentiation.

The presence of proteins (p17 and p24 core proteins, gp41 envelope protein) and mRNA (gag/pol and env gene segments) of human immunodeficiency virus type-1 (HIV-1) was analyzed on frozen tissue sections of lymph nodes from HIV-1 infected individuals. Thirty-one lymph nodes were categorized in the stages of follicle hyperplasia (n = 18), follicle degeneration (n = 5), and total depletion (n = 8). The follicle dendritic cells in germinal centers showed the presence of core proteins and, to a lesser extent, gp41. The staining patterns, being similar to those of immunoglobulins, suggested that they occur in the form of immune complexes. In addition there were solitary cells expressing viral protein, in particular gp41, and mRNA. The number of mRNA-positive cells was very low: about five positive cells were observed in a tissue section with about ten (hyperplastic) follicles. HIV-1-mRNA-positive cells were observed both in follicles and interfollicular areas and showed no differences between various stages. The extent and intensity of distinct HIV-1 proteins and HIV-1-mRNA gene segments in follicles were significantly correlated, as was their presence in interfollicular areas. No significant correlation was found between the presence of HIV-1 components in follicles and in interfollicular areas. This indicates that processes involving HIV-1 components occur in a segregated manner in both lymph node compartments. The presence of HIV-1 components did not correspond to any clinical classification (CDC criteria), nor to other histochemical characteristics. An exception was the correlation between gp41-positive cells and CD1-positive interdigitating cells in the interfollicular areas.

The immunohistological findings in the thymus after bone marrow transplantation were studied in autopsy samples from 12 patients who had received allogeneic grafts as treatment for acute leukemia. The findings were compared with those in samples from normal individuals and from conventionally treated leukemic patients. The thymuses were hyperinvoluted in all grafted and nongrafted subjects. The remnants were composed of subcapsular and medullary epithelium which expressed the same phenotype as the normal thymus controls. Most samples also contained small remnants of cortical epithelium which lacked normal expression of HLA-DR antigens. The intraepithelial and stromal thymic lymphocytes were virtually all mature T cells, and no immature cortical thymocytes were seen. With the use of HLA-typing methods in 2 recipients of one-haplotype-matched grafts no donor cells could be identified in any of the thymic components. These findings provide no evidence for a functional role for the thymus in the differentiation of donor-derived precursor T cells, at least in the early period after transplantation.