Biomedical subjects
Publications and source records attributed to H C Ertl.
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The H-2 restriction pattern of cytolytic T lymphocytes (Tc) and T lymphocytes which mediate a delayed-type hypersensitivity response (Td) directed against infectious Sendai virus was investigated using H-2 mutant mice. Td and Tc lymphocytes exhibit the same fine specificity for self-recognition, for example, B6.C-H-2bm1 effector T cells were unable to recognize viral antigens in association with wild-type Kb and vice versa, B6.H-2bm6 effector cells did not mediate a reaction against virus plus wild-type Kb but, on the other hand, T cells of wild-type Kb recognized virus plus Kbm6 BALB/c-H-2dm2 T cells lacked reactivity against virus in association with wild-type Dd, but again wild-type Dd effector cells recognized virus plus Ddm2.
T helper cells for the promotion of Sendai virus-specific antibody production were generated in vitro. They could be stimulated by infectious, UV light-inactivated or fusion-negative Sendai virus, which had to be presented by adherent cells. Induction of T helper cells was virus-specific and required H-2 IA region compatibility between T cells and antigen-presenting cells. Delivery of help to B lymphocytes was neither virus-specific nor H-2-restricted.
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The intrathymic versus extrathymic influences on H-2-restriction specificity of K,D- and I-region-restricted Sendai virus-immune T lymphocytes, which mediate a delayed-type hypersensitivity response in vivo, were investigated. K,D- and I-region-restricted Td lymphocytes of P1 leads to F1 fetal liver chimeras showed preference but no absolute restriction for the P1 haplotype. T effector lymphocytes of thymic chimeras expressed a slightly higher degree of restriction for the haplotype of the thymus graft than F1 leads to P1 chimeras, which might reflect the activity of T lymphocytes of thymic origin. The lack of absolute restriction of both K,D- and I-region-restricted Td lymphocytes to the haplotype the thymus suggests an additional pathway of T-cell maturation.
Mice injected with inactivated (UV light-irradiated) influenza virus produce specific antibody, become sensitized for a delayed-type hypersensitivity reaction, but do not generate specific cytotoxic T (Tc) cells. If injected 4-5 days later with infectious virus, the formation of Tc cells is suppressed by > 90%. If A strain viruses are used, the suppression observed is cross-reactive within A strain viruses but does not extend to B/LEE or to Sendai virus. Serum from mice injected with UV-irradiated virus contains antibodies which on adoptive transfer can inhibit Tc cell formation when infectious homologous virus is used to challenge the recipients. Spleen cells from the same mice, upon adoptive transfer, also inhibit (50-70%) Tc cell formation if transferred within 24 h of injection of infectious virus, and the specificity pattern observed is cross-reactive within A strains. The activity of the cells mediating suppression is destroyed by monospecific anti-Thy-1.2 antibody and complement. The immune cells require I region sharing between donor and recipient mice for their suppressor activity to be effective. (There is also a partial requirement for K, D region sharing, but the possible rejection of transferred cells is not excluded.) Dilution assays in which clonal expansion of Tc precursors is used to estimate their frequency and the presence of T helper (Th) cells indicate that suppressed mice possess Tc precursors and primed cells which, upon restimulation, act as Th cells. Furthermore, injection of irradiated Th cells with inactivated virus does not significantly reduce the ensuing suppression.
An enzyme-linked immunosorbent assay (ELISA) for the detection of antibodies to Sendai virus, a paramyxovirus, is described. The assay was found to be about 20-fold more sensitive than the hemagglutination inhibition assay. Differentiation between virus specific IgG and IgM is possible. The test appears to be especially useful in the study of early events in antibody formation in vivo as well as in vitro.
Vaccinia virus-infected cells were treated enzymatically to remove H-2 antigenic sites. The effect of this procedure on virus-specific cell-mediated cytolysis (CMC) and virus-specific antibody-mediated cytolysis (AMC) was tested. Due to the inhibition of cellular proteinsynthesis by the vaccinia virus infection, H-2 antigenic sites were not resynthesized while there was a continuous production of viral surface antigens. These cells with a high concentration of viral surface antigens and decreased H-2 determinants could be used as targets in the virus specific AMC which emphasizes the significance of H-2 antigens during recognition of virus-specific determinants by T cells.
N-beta-(2-acetamido-2-deoxy-beta-D-glucopyranosyl)-asparaginyl peptides [Asn(GlcNAc)] corresponding to T-helper cell determinants were synthesized on solid-phase. Various amino-terminal- and carbohydrate-protecting groups were used on the glycosylated asparagine residue which was coupled to the peptide chain. We found that coupling rates decreased with increased size of the protected carbohydrate part of the acylating agent. Double couplings with an O-unprotected saccharide, as in Fmoc-Asn(GlcNAc)-OH resulted in acceptable coupling rates even with a synthetically difficult sequence corresponding to the T-cell epitopic peptide from the C-terminus of pigeon cytochrome c. The observed coupling rates on this peptide as well as on a T-cell epitopic pentapeptide, derived from the rabies virus N-protein, were comparable to those of conventional solid-phase peptide syntheses. The Fmoc-Asn(GlcNAc)-OH used can be prepared easily from commercially available components. The described glycopeptides will be used to probe effects of N-glycosylation on the immune recognition of viral glycoproteins.