H-2 complementation in anti-H-Y cytotoxic T-cell responses can occur in chimeric mice

T cell mediated cytotoxic immune reactivity of bone marrow reconstituted chimeric mice

The capacity of bone marrow reconstituted chimeric mice to mount sendai virus specific H-2 restricted as well as alloreactive cytotoxic T-cell responses has been investigated. Chimeras of the type a leads to (a x b)F1 and (a x b)F1 leads to a were used. In addition chimeras produced with (a x b)F1 mice grafted under the kidney capsula with a type parental thymus, thymectomised, lethally irradiated and reconstituted with either a, (a x b)F1 or b type bone marrow cells were tested. In agreement with the data of Zinkernagel and Bevan it was noted that virus specific T cells of semi-allogeneic chimeric mice are able to recognise virus antigens in the context of the MHC of the thymus in which they have maturated. The unexpected finding was that fully allogeneic chimeras were able to mount both alloreactive CTL and H-2 restricted, virus specific CTL. The H-2 restricted CTL detected were preferentially restricted to their own MHC type. In some animals also virus specific CTL restricted to the allogeneic thymus MHC type were observed. Data are also presented to indicate that longterm cultured bone marrow cells have the potential to repopulate lethally irradiated mice.

H-Y antigen: genetic control of the expression as detected by host-versus-graft popliteal lymph node enlargement assay maps between the T and H-2 complexes

We are using the terms 'low' and 'high' expression when the H-Y antigen on thymocytes of mouse parental strains is, respectively, weakly and strongly immunogenic for F1 hybrids in a host-versus-graft popliteal lymph node enlargement assay. Using this assay we attempted to locate the genetic factor(s) responsible for the control of H-Y expression within chromosome 17 since our previous study indicated linkage with the H-2 complex. We produced to this aim recombinants from (B10.T X C3H/Di)F1 hybrids where crossing over took place between H-2 and T complexes. In this way we were able to locate a gene denoted Hye (for H-Y expression) whose 'high' and 'low' alleles originated, respectively, from the B10 and C3H/Di strains. In the recombinants, the expression did not follow the H-2 haplotype, but obviously depended on the position of crossing over between H-2 and T. This pointed to the Hye gene mapping proximally from the H-2 complex.

Patterns of virus-immune T-cell responsiveness. Comparison of (H-2k X H-2b) leads to H-2b radiation chimeras and negatively selected H-2b lymphocytes

Negatively selected H-2K(b)D(b) TDL can be induced to respond strongly to vaccinia virus presented in the context of both H-2K(k) and H-2D(b) when stimulated in irradiated H-2K(k)D(b) recipients. Addition of excess (H- 2K(k)D(b) x H-2K(b)D(b))F1 TDL, which are low responders to H-2D(b)-vaccinia virus, does not obviously suppress the reactivity pattern of the H-2K(b)D(b) T cells. However, lymphocytes from chimeras made by reconstituting H- 2K(b)D(b) mice with (H-2K(k)D(k) x H-2K(b)D(b))F(l) bone marrow cells make little, if any, cytotoxic T-cell response to vaccinia virus when sensitized in H-2K(k)D(b) recipients. We have thus documented one instance where the responder phenotype of T ceils from an F(l) {arrow} parent chimera is not equivalent to that associated with the H-2 type of the parental thymus. Lymphocytes from both the chimera and the H-2K(b)D(b) parent (after negative selection) are tolerant to the H-2K(k) and I-A(k) alloantigens encountered in the recipient, but the chimera T cells are also defective in their response to a neoantigen (vaccinia virus) presented in the context of H-2K(k) which the parental T cells invariably recognize. It is thus possible that at least part of the phenomenology associated with the F(l) {arrow} parent radiation chimeras reflects deletion of repertoire in the context of H-2 antigens present during thymocyte ontogeny on other than radiation-resistant thymic epithelium.

H-2-linked control of cytotoxic T-cell responsiveness to alphavirus infection. Presence of H-2Dk during differentiation and stimulation converts stem cells of low responder genotype to T cells of responder phenotype

Secondary Tc cells generated against Sindbis virus (SIN) are restricted to Dk. All other H-2K or D regions tested show low specific responsiveness. F1 hybrids between low and high responders show dominance of responsiveness but lack complementation. When BALB/c (KdIdDd) low responder fetal liver stem cells were allowed to mature in irradiated high responder recipients C3H.OH (KdIdDk) a response to Dk plus SIN could be generated with Tc cells of BALB/c origin. This result, together with the failure of complementation in the F1 hybrids, implies that the lesion of low responsiveness is in the inability of viral antigen to stimulate a Tc-cell response in association with any self H-2K or H-2D molecule (of those tested) other than H-2Dk. Hypotheses compatible with these data are discussed.