GENERATION OF T-CELLS WITH LYTIC SPECIFICITY FOR ATYPICAL ANTIGENS .2. A NOVEL ANTIGEN SYSTEM IN THE RAT DEPENDENT ON HOMOZYGOUS EXPRESSION OF MAJOR HISTOCOMPATIBILITY COMPLEX GENES OF THE CLASS-I-LIKE RT1C REGION

Lymphocytes from parental strain DA rats can induce potent killer cell responses to atypical antigen systems in F1 Lewis (L)/DA and DA/L recipients. Here, we describe an antigen system, H, present on homozygous parental target cells, but not on F1 cells. This antigen system is unusual in several respects: it does not involve class I RT1A gene products usually used by killer cell responses in the rat, it maps to the major histocompatibility complex (MHC) class I-like RT1C region, and it requires homozygous expression of RT1C(av1) alleles. This may be another example, this time involving the RT1C region, of an MHC gene product antigenically altered by an MHC-linked trans-activating modifier gene.