Rapid responses of lymphocytes in an optimized mixed lymphocyte culture.

When adherent mononuclear cells are removed from whole blood, the separated lymphocytes respond rapidly by proliferation to foreign cocultured lymphocytes. The reaction of responding cells against a pool of foreign stimulating cells can be detected in this rapid mixed lymphocyte culture (r-MLC) within 28 h and antigenic disparity between family members, differing for only one HLA haplotype, can be measured within 36 h. These early responses show genetic specificity corresponding to those observed in a standard MLC at 96 h. The involvement of similar cell populations in the regulation of early responses to allogeneic cells and increased responses to autologous cells in r-MLC, as well as accelerated responses in secondary MLC, is discussed.