Maintenance of immunological memory: A role for CD5+ B cells?

How memory is retained is an immunological mystery. One possibility, argued here by Fons UytdeHaag and colleagues, is that memory is imprinted in the somatically-mutated Ig expressed by certain CD5+ B cells. The theory proposes that the Ig expressed by this self-renewing population acts as surrogate antigen, selecting and stimulating emerging antigen-specific lymphocytes

Rabies virus cross-reactive murine T cell clones: analysis of helper and delayed-type hypersensitivity function.

Three T cell clones derived from rabies virus-immunized BALB/c mice were analysed for specificity and function. The clones proved to be broadly cross-reactive by responding to different rabies virus isolates (PM, ERA, CVS, HEP) and other representatives of the genus Lyssavirus, like the Duvenhage-6 (DUV6) and Mokola (MOK) viruses. The clones detected three different epitopes: an epitope expressed on the matrix protein (M) shared by PM, HEP, MOK and DUV6 viruses (clone AA8), an epitope expressed on the M-protein shared by PM, ERA, CVS, HEP and MOK viruses (clone 35A) and finally an epitope expressed on the glycoprotein (G-protein) shared by PM, ERA, CVS, HEP and MOK viruses (clone BG2). Antigen recognition of all clones proved to be MHC-restricted and they all displayed the CD4+ CD8- phenotype. Intravenous inoculation of the T cells in syngeneic mice, which had been injected intracutaneously in the ear with HEP virus, resulted in a localized DTH reaction characteristic for TH1 cells. In vitro, the clones were able to provide help to rabies virus-primed B cells, resulting in the production of virus-specific antibodies directed against all the four structural proteins of rabies virus. Further analysis of this antibody response revealed that part of it was directed against antigenic determinants of the G-protein which induce virus neutralizing antibody

Localization of human antigen-specific helper and suppressor function in distinct T-cell subpopulations

Distinct human T-cell subpopulations were isolated and cultured in the presence of B-cells and antigens. After an incubation period of 6 days cells were tested for their capacity to secrete antigen-specific antibodies in the PFC-assay. The results indicate that the T-helper activity for the antigen-induced T-dependent B-cell differentiation is located in the Tμ-subpopulation, whereas the suppressor-cell activity is confined to the Tγ-subpopulation

Localization of human antigen-specific helper and suppressor function in distinct T-cell subpopulations

Distinct human T-cell subpopulations were isolated and cultured in the presence of B-cells and antigens. After an incubation period of 6 days cells were tested for their capacity to secrete antigen-specific antibodies in the PFC-assay. The results indicate that the T-helper activity for the antigen-induced T-dependent B-cell differentiation is located in the Tμ-subpopulation, whereas the suppressor-cell activity is confined to the Tγ-subpopulation

Localization of human antigen-specific helper and suppressor function in distinct T-cell subpopulations

Distinct human T-cell subpopulations were isolated and cultured in the presence of B-cells and antigens. After an incubation period of 6 days cells were tested for their capacity to secrete antigen-specific antibodies in the PFC-assay. The results indicate that the T-helper activity for the antigen-induced T-dependent B-cell differentiation is located in the Tμ-subpopulation, whereas the suppressor-cell activity is confined to the Tγ-subpopulation

Human anti-idiotypic T lymphocyte clones are activated by autologous anti- rabies virus antibodies presented in association with HLA-DQ molecules.

The regulatory function of antigen-specific T cells in human antibody responses to protein and carbohydrate determinants of many viral and bacterial antigens has extensively been studied in systems involving in vitro triggering of B cells by antigens or polyclonal activators. Although amply documented in experimental murine models, the existence of T helper cells with receptor specificity for idiotypic determinants of B cell immunoglobulins has not been demonstrated in a human system. We are interested in T helper cell recognition of idiotypic determinants of virus-specific antibody, secreted by human B cells in response to viral antigens, and in the role which such idiotype-specific T helper cells play, alone or in concert with virus-specific T helper cells, to regulate the antibody response. Understanding of the function of different T helper cell subsets in an anti-viral antibody response and especially of the mechanisms of idiotype recognition by T cells is important for the development, and future application in man of idiotype vaccines, the potential of which has been indicated for different pathogens in several animal species. It was realized that for the efficient characterization of each of the T helper cell subsets, the availability of cloned populations of T cells would be inevitable. Furthermore, we argued that if, as predicted by Jerne, idiotype recognizing T helper cells are involved in physiological idiotype regulation in the course of an immune response--e.g., following encounter with vir