PROLIFERATION OF IMMATURE T-CELLS WITHIN THE SPLENOCYTES OF ATHYMIC MICE BY PSEUDOMONAS EXOTOXIN-A

Pseudomonas aeruginosa exotoxin A has been shown to stimulate splenocy tes from athymic nude mice. The present studies were performed to char acterize the exotoxin A-responsive cells within the splenocytes of ath ymic nude mice. The results of these studies indicate that exotoxin A- responsive cells were represented in the nylon woof-adherent cell popu lation and in the Ig-depleted splenocyte population (IgNA). Flow micro fluorimetry analysis indicated that exotoxin A induced the expansion o f Thy1(+), CD3(-), CD4(-), and CD8(-) cells which also expressed the h eat-stable antigen (HSA), an antigen expressed on immature T lymphocyt es. Depletion of Thy1(+) cells abrogated the exotoxin A-induced prolif eration; however, depletion of CD4(+) and CD8(+) cells did not affect the exotoxin A-induced proliferation of IgNA cells. Thus, the results indicate that exotoxin A stimulates the proliferation of immature T ce lls within the splenocytes of nude mice that are Thy1(+), HSA(+), CD3( -), CD4(-), CD8(-). (C) 1994 Academic Press, Inc.