APOPTOSIS IN THYMUS OF ADULT XENOPUS-LAEVIS

Thymocyte apoptosis in adult Xenopus laevis is demonstrated on agarose gels and is quantified by propidium iodide incorporation using flow c ytometry. Basal apoptotic levels are increased after in vitro exposure to a glucocorticoid, dexamethasone (DEX), and to the lectin, phytohem agglutinin (PHA). To determine the role that newly introduced antigeni c determinants may play in this regard, a repertoire of altered-self a ntigens was created by exposing thymuses in vitro to trinitrobenzene s ulfonic acid (TNBS) thereby derivatizing self-cells and proteins via 2 ,4,6-trinitrophenylacetic acid conjugation. An increase in apoptosis i n TNBS-treated thymuses is observed. Thus, the thymocytes of adult Xen opus laevis are susceptible to apoptosis when induced by a glucocortic oid, a lectin, and by altered self, antigen activation.