Cross-reactivity of T cell lines and clones to beta-lactam antibiotics

To clarify on a molecular level the specific T cell response to haptens like penicillin G, we generated T cell lines and clones from penicillin-allergic patients, Two types of beta-lactam reactivity of T cells could be delineated: one group of patients showed a rather restricted specificity, as the penicillin-elicited T cell lines generated from such donors proliferated only to the stimulating penicillin, but not to other beta-lactam antibiotics nor to cephalosporines, even if the side chain was identical, This indicates that the penicilloyl structure together with the side chain was recognized by these T cells, The second group comprised patients with more broadly reactive T cells, as they were restimulated by penicillin G as well as by related penicillins like amoxicillin or ampicillin, but not cephalosporines. This indicates that the penicilloyl structure, a common motif of penicillins, was important for T cell recognition, Clones generated from a broadly reactive patient confirmed this heterogeneity, as either monospecific or broadly specific T cell clones could be identified, This broad or very restricted pattern of T cell reactivity was reflected in the use of TCR V beta-chains: while the broadly reactive T cell lines showed a heterogenous TCR usage, the highly restricted T cell lines showed an up regulation of one TCR V beta-chain, Thus, our data suggest that the outgrowth of T cells bearing a certain TCR V beta may be a sign of a limited cross-reactivity.