Analysis of human prenatal and postnatal thymocytes with the anti-Tac monoclonal antibody and recombinant interleukin-2

The expression of the interleukin-2 (Il-2) receptor on the cell surface membrane of human prenatal and postnatal thymocytes has been studied by flow cytometry. The in vitro responsiveness of these thymocytes to human recombinant Il-2 (rIl-2) was also studied. Prenatal and postnatal thymocytes contained very few Tac positive cells. The different T cell antigens T6, T3, T4, T8, T9, T10, 3A1 and T11 were expressed by the first trimester of fetal development. Recombinant Il-2 alone was able to induce proliferation of human prenatal and postnatal thymocytes. From this study and data in the literature we conclude that hither-to a thymic precursor cell carrying the interleukin-2 receptor as is the case for the murine thymus has not been found in man.     

Cytotoxic T lymphocytes generated across and I-Ab mutant difference are directed against a molecule bearing Ia antigens

The recently discovered B6.C-H-2bm12 (bm12) histocompatibility mutant bears a mutation of the I-A subregion of the H-2b haplotype. We have studied cytotoxic T lymphocytes (CTL) generated in secondary mixed lymphocyte culture (MLC) between the bm12 mutant and the strain of origin C57BL/6 (B6). In both directions, strong CTL responses were generated against lipopolysaccharide-stimulated, but not against concanavalin A-stimulated target cells. Studies of the specificity of the bm12 anti-B6 CTL response, using target cells from a panel of H-2 recombinants, showed that the CTL were directed against specificities of the I-Ab subregion. This conclusion was confirmed by the observation that the bm12 anti-B6 CTL could be specifically blocked by anti-Iab, but not by anti-Kb antisera. EL4 tumor cells, which express Kb and Db but not Iab antigens, were not lysed by the CTL. The combined data confirm that bm12 is an I-A subregion mutant and indicate that the I-A subregion antigens, recognized by antibody and those recognized by CTL, are probably present on the same molecules. The CTL effector cells generated in secondary MLC across the I-Ab mutant difference had the surface phenotype Lyt 1- 2+.     

Increased HLA-DR homozygosity associated with pre-eclampsia

It is generally accepted that maternal recognition of paternally derived fetal antigens occurs during normal pregnancy and may be beneficial for implantation and maintenance of gestation. Thus, we have investigated the human leukocyte class II DR antigens (HLA-DR), whose role in self and non-self recognition is well known, in women with pre-eclampsia, their partners and in control couples. The HLA-DR antigens were tested in 70 pre-eclamptic primigravidae women and their partners and 70 healthy control couples using the serological Terasaki technique. Our results did not show any particular HLA-DR antigen to be correlated with pre-eclampsia, but a statistically significant increase of only one identifiable HLA-DR antigen, which was presumed to express homozygosity at the HLA-DR locus, in the pre-eclamptic women and their partners: 67.1 versus 7. 9% in the control couples (P < 0.000001). The analysis of HLA-DR compatibility between pre-eclamptic women and their partners showed a statistically highly significant increase of the female-to-male compatibility (P = 0.0003) and a lower but significant male-to-female compatibility in comparison with controls (P = 0.014). From our results, it emerges that HLA-DR homozygosity and reduced antigenic disparity seem to be associated to a major risk for pre-eclampsia, which consequently appears to be a 'couple's disease'.     

Inflammation, depressive symptomtology, and coronary artery disease

OBJECTIVE: Many patients feel exhausted or depressed before the onset of an acute coronary event, but little is known about the origin of these feelings. We tested the hypothesis that the depressive symptomatology is associated with a reactivation of latent viruses and inflammation of a coronary vessel. METHODS: A blood sample was drawn and a biopsy sample was obtained from the coronary lesion of 15 exhausted and 15 nonexhausted patients treated with directional coronary angioplasty because of severe angina. Blood samples were analyzed to measure antibody titers against Chlamydia pneumoniae, cytomegalovirus, and the cytokines interleukin (IL)-1beta, IL-6, and tumor necrosis factor (TNF)-alpha. The biopsy sample was analyzed for the presence of IL-1beta and TNF-alpha. RESULTS: Exhausted/depressed patients had higher antibody titers against cytomegalovirus, higher levels of C. pneumoniae immunoglobulin G, and higher levels of IL-1beta and TNF-alpha. No associations between the mental state of a patient and cytokine mRNA in the biopsy sample were found. CONCLUSIONS: The findings indicate that the mental state of angioplasty patients is positively associated with serological markers of inflammation. It remains to be seen whether the inflammation causes feelings of exhaustion, whether exhaustion and depression set the stage for inflammation, or whether existing feelings of exhaustion are amplified by the inflammation.     

Clonal heterogeneity of HLA-B27 cellular allorecognition. Delineation of immunodominant sites

The fine specificity of nine cytolytic T lymphocyte (CTL) clones obtained after stimulation of HLA-B27- responder lymphocytes with B27.1+ lymphoblastoid cell lines has been analyzed. These clones defined three different reaction patterns when tested against a panel of target cells including those expressing all known HLA-B27 subtypes: (a) specific recognition of HLA-B27.1, B27.2 and B27d, (b) selective reactivity with B27.1, B27d and HLA-B40 and (c) selective recognition of B27.1, B27.2, B27d, B27f and B40. Representative clones within each group were analyzed in detail. Differences in lytic ability of the various susceptible targets within each group were established by cold target inhibition analyses and by blocking experiments with anti-CD3 and anti-CD8 monoclonal antibodies. When correlated with the known structure of the HLA-B27 subtypes, these results demonstrate the critical relevance of amino acid changes within residues 77-81 and at position 152 in modulating allospecific CTL recognition of HLA-B27.1 and suggest that these residues could be involved in the structure of immunodominant regions of this antigen. The observed cross-reactions with HLA-B40, differing from B27.1 in 16 amino acid residues, suggest that the simultaneous occurrence of multiple amino acid changes could have mutually compensatory effects, so that a cross-reactive epitope might result from various combinations of polymorphic residues.     

Comparison of the enzyme linked immunosorbent assay, the haemagglutination inhibition test and the agar gel precipitation test for the detection of antibodies against infectious bronchitis and Newcastle disease in commercial broilers

Serological results as obtained by the agar gel precipitation (AGP) test, haemagglutination inhibition (HI) test (M41, D274, D1466) and an enzyme linked immunosorbent assay (ELISA) from commercial broiler flocks, which had suffered from a clinical infectious bronchitis (IB) infection in the fattening period, were compared with serological findings of control broiler flocks. In addition the Hi-test and ELISA for Newcastle disease (ND) were compared. The AGP results differ significantly between groups. The test had a low sensitivity. The results of the HI-IBV tests were similar for both groups and no difference was seen between flocks with or without clinical IB problems. The IBV ELISA showed a highly significant difference between the two groups. In contrast to the low and not significant correlation coefficients (r) between the IBV HI tests and the ELISA, the value of r between the NDV HI and ELISA was high. The results indicate an ELISA as the preferred test for the diagnosis of IB in broilers.     

K88 fimbriae as carriers of heterologous antigenic determinants.

The K88 fimbriae of enterotoxigenic Escherichia coli are strongly immunogenic antigens that can be used to evoke protective immunity. To find out whether these fimbriae can be used as carriers for foreign epitopes, a highly variable region present in the primary structure of the different K88 variants was replaced with five different heterologous epitopes to investigate to what extent these insertions affected the expression, assembly (biogenesis), stability and immunogenic properties of the resulting hybrid fimbriae. Amino acid residues 163-173, were replaced using site-directed in vitro mutagenesis and the hybrid fimbriae were tested for these aspects using ELISA, immunoelectronmicroscopy and immunoblotting. Replacement of this highly variable region did not affect the biosynthesis of fimbriae, although all mutations tested resulted in a reduced expression depending on the epitope inserted. Testing of the different hybrid fimbriae with a panel of monoclonal antibodies raised against the various K88 serotypes K88ab, K88ac and K88ad indicated that replacement of amino acid sequence 163-173 did not affect conserved or K88ab specific epitopes but the K88ac and K88ad specific conformation was lost. Immunization with hybrid fimbriae raises antibodies specific for the inserted heterologous epitopes.