RECONSTITUTION OF GERMINAL CENTER FORMATION IN NUDE-MICE WITH TH1 ANDTH2 CLONES

We investigated the ability of hemocyanin (KLH)-specific cloned CD4(+) T cells expressing defined cytokine profiles to support germinal cent er (GC) formation in syngeneic athymic recipients in response to hapte n-KLH challenge. Th1 clones producing IL-2 and IFN-gamma did not by th emselves increase GC production above background, while Th2 cells prod ucing IL-4 and IL-5 did. However, the combination of Th1 and Th2 cytok ines was more effective than Th2 cytokines alone, suggesting a synergi stic effect in this aspect of their help for B cells. In contrast to G C formation, antibody production could be induced with Th1 or Th2 clon es given separately (Th1 clones inducing IgG2a, and Th2 clones inducin g IgG1 and IgE). These results indicate that the T cell requirements f or GC production are different from those for isotype switching and Ig secretion. It is postulated that the synergy between Th1 and Th2 cell s in the induction of GC formation reflects the synergy between Th1 an d Th2 cytokines, such as IFN-gamma and IL-5, in promotion of GC cell p roliferation. (C) 1996 Academic Press, Inc.