Convergence between CD98 and integrin-mediated T-lymphocyte co-stimulation

CD98 is a widely expressed cell surface heterodimeric glycoprotein, which i s rapidly up-regulated upon activation of T lymphocytes. Monoclonal antibod y (mAb) 80A10 recognizes an epitope on CD98 and in combination with CD3 ant ibody causes proliferation of peripheral blood T lymphocytes. CD98 co-stimu latory activity, mediated by either mAb 80A10 or 4F2, a well-characterized CD98-specific mAb, is blocked in the presence of the soluble beta 1 integri n antibody 18D3. Previously we have reported that co-stimulatory activity o f antibodies to integrins alpha(4)beta(1), alpha(5)beta(1), alpha(L)beta(2) and alpha(4)beta(7) is inhibited by 18D3, whereas co-stimulation mediated by non-integrins was unaffected. Thus the non-integrin CD98 is uniquely sen sitive to the inhibitory effects of beta(1) integrin-blocking antibodies, w hich may reflect convergent signalling mechanisms between integrins and CD9 8. This is consistent with recent reports suggesting that CD98 may regulate integrin-mediated adhesive events.