Mutual Recognition of Parental and F 1 Lymphocytes

The injection of F1 hybrid animals with parental spleen or lymph node cells leads to the activation of specific parental lymphocytes which recognize major histocompatibility complex (MHC) 1 -coded antigens of the other parental haplotype expressed by the F1 host (1). Such recognition can result in graft-vs.-host (GVH) reactions which are frequently associated with depressed in vivo cell-mediated immune functions, such as resistance to bacterial infection (2), skin graft rejection (2, 3), T-helper cell dysfunction (4), as well as antibody responses to thymic-dependent and -independent antigens (5-8). The depression of T-cell-mediated lympholysis (CML) responses by cells from F1 hybrid mice injected with parental lymphocytes has not been reported but could provide a useful approach for investigating T-cell receptors because self MHC-restricted as well as allogeneic C M L responses can be analyzed. This report describes an experimental system in which intravenous injection of F1 hybrid mice with parental T-splenic lymphocytes can result in the abrogation or severe depression of CML potential. This loss of CML activity did not appear to be specific for self determinants because responses to alloantigens, trinitrophenyl (TNP)modified F1 cells (TNP-self), and TNP-modified parental cells were all affected. However, an unexpected finding was the observation that the parental-induced CML depression was dependent upon the H-2 type of the injected parental lymphocytes. Thus, the injection of H-2 a, H-2 k, or H-2 a, but not H-2 6, parental lymphocytes resulted in depressed CML potential. These findings are discussed with respect to (a) the selective resistance of F1 mice to H-2 b parental lymphocytes, and (b) the possibility that Fa lymphocytes recognize idiotypic determinants specific for non-H-2 b antigens on H-2 b lymphocytes, but not those for H-2 b antigens on non-H-2 b lymphocytes.