MHC recognition by clones of Mls specific T-lymphocytes

To test whether Mls determinants like other non-MHC or nominal antigens, are recognized by T-cells in association with H-2 determinants, the in vitro proliferative responses of T-cell lines and clones were studied. Lines and clones were prepared by soft agar cloning (B10.BR X BALB/c)F1 (H-2k/H-2d Mlsb/Mlsb) t-cells responding in a primary MLR to AKD2F1 (H-2k/H-2d, Mlsa/Mlsa) stimulator cells. All the T-cell clones obtained could respond equally well in a proliferative assay to the Mlsa determinant in association with the H-2 haplotype of either parent, i.e., DBA/2 (H-2d, Mls), and AKR (H-2K, Mlsa) both stimulated equally well. When the T-cell lines and clones were screened against stimulators from recombinant inbred (RI) strains, it became apparent that strains exhibiting the H-2b, Mlsa genotype stimulated poorly or not at all. This shows that the T-cell response to Mlsa involves MHC recognition, and raises the possibility that the response to Mlsa can involve recognition of H-2 specificities shared between the H-2k and H-2d haplotypes.