The role of two polymorphic H-2 domains for the generation of alloreactive and H-2 restricted CTL clones

With a set of mc anti-H-2 antibodies to major, spatially separate polymorphic domains, A and B could be identified on the H-2K(k) molecule. Target inhibition by mcAb demonstrates that these two domains harbor also the target sites for alloreactive CTL, and also the restriction sites for H-2 restricted CTL. The majority of both alloreactive and H-2 restricted CTL obtained in mass cultures appeared to be reactive against cluster B determinants. However, in limiting dilution systems several distinct subpopulations were found which differed in their receptor repertoire. Thus, the low frequency populations were predominantly specific for cluster B while the high frequent population contained mainly CTL clones which recognize cluster A. The appearance of these cluster-specific subpopulations seems to be regulated by yet unknown suppressive mechanisms.