Different specificities of cloned Τ cells assessed by in vitro proliferation assays and by the ability to mediate skin graft rejection in vivo

The experiments presented here have compared the specificities of T cell clones as determined by in vitro proliferative responses and their specificities as reflected by their ability to mediate skin graft rejection in vivo. Two proliferative T cell clones with distinct in vitro specificities were evaluated for their ability to mediate rejection of skin grafts from C57BL/10 Sen nu/nu mice. Clone 14.11 (L3T4⁺, Lyt2⁻) was specifically stimulated to proliferate in vitro by I-A^d determinants, while clone 3.3.10 (also L3T4⁺, Lyt2⁻) recognized M1s^a products in the context of МНC-encoded cell surface determinants. The results demonstrate that both clone 14.11 and clone 3.3.10 T cells are capable of mediating rejection of DBA/2 (H-2^d, M1s^a) skin grafts from B10 nu/nu mice. Surprisingly, neither clone 3.3.10 T cells nor clone 14.11 T cells were found to be effective at rejecting skin grafts from the D1.C congenie donor strain of mice (also H-2^d, M1s^a) from BIO nu/nu mice. Further, clone 14.11 T cells were also found to be ineffective at rejecting B10.D2 (Н-2^d, M1s^b) skin grafts from B10 nu/nu mice. These data indicate the existence of a striking dichotomy between the specificity of alloreactive T cell clones as determined by in vitro proliferation studies and their functional capabilities in vivo.