In vivo expression and function of hybrid Ia dimers (E(α)A(β)) in recombinant and transgenic mice

We have found cell surface expression of an E(α) molecule in recombinant and transgenic mouse strains lacking an E(β) molecule. Flow cytometry has shown low level expression of E(α) in B10.RQB3 (I-A(q)E(α)(k)) and B10.RFB2 (I-A(f)E(α)(k)) mice. We have also found that B10.Q (H-2(q)) mice can express the E(α)(k) transgene. Since these strains do not have functional E(β) chains, we propose that the E(α)A(β) hybrid dimers are formed in low numbers and can be picked up by FACS analysis. So far we have not been able to identify these hybrid molecules by cytotoxicity or immunoprecipitation. The E(α)/A(β) molecule can function in vivo during thymic selection in the clonal deletion of two V(β) TCR subsets, V(β)11 and V(β)6, which have been shown to interact with the intact I-E molecule.