H-2 homology requirements for secondary cell-mediated lympholysis and miced lymphocyte reactions to TNP-modified syngeneic lymphocytes.

Secondary cell-mediated lympholysis (CML) and mixed lymphocyte reactions (MLR) were generated in a tissue culture system against trinitrophenyl (TNP)-modified murine syngeneic spleen cells. H-2 homology between primary and secondary TNP-modified stimulating cells was required in order to restimulate in the secondary CML. Strong proliferative responses (MLR) were detected only in the secondary cultures, for which H-2 homology was also required between TNP-modified primary and secondary immunogens. Intra-H-2 mapping for the secondary MLR indicated that the relevant regions of homology were I, D, and K and/or I-A. Homology throughout the entire major histocompatibility complex or at K plus I-A gave stronger MLR than did cultures in which there was homology between the primary and secondary phases at I or D only.