Not only Th2 cells but also Th1 and Th0 cells express CD30 after activation.

To investigate whether the CD3O mole- cule, expressed only by a minority of T and B cells, defines a subtype of T helper cells, Pityrosporum orbiculare-specific CD4' T cell clones were assessed for CD3O protein and gene expression. The clones were defined as Thi, ThO, and Th2 according to their cytokine mRNA profile detected by reverse transcrip- tion PCR (RT-PCR). The kinetics ofCD3O expression after OKT3 (anti-CD3) stimulation was analyzed by flow cytometry, immunocytochemistry, and RT-PCR. OKT3 activation induced a high expression of CD3O in cells ofboth Thi and ThO as well as Th2 type after 1-3 days. A difference between the clones was noted in that the Th2 clones remained highly positive in CD3O expression, whereas expression in the other clones started to decline from day 3. These data indicate that CD3O is expressed in activated CD4+ T cells of all three subtypes, and that the expression is sustained in Th2 cells. J. Leukoc. Biol. 58: 683-689; 1995.