The Hsp90-specific inhibitor, geldanamycin, blocks CD28-mediated activation of human T lymphocytes.

The 90 kDa heat shock protein (Hsp90) is a molecular chaperone aiding the folding of nuclear hormone receptors and protein kinases. Hsp90-mediated folding can be disrupted by the Hsp90-specific drug, geldanamycin. Here we provide evidence for the inhibition of the CD28-specific BW 828 antibody-mediated activation of human T lymphocyte proliferation, IL-2 secretion and IL-2 receptor expression by geldanamycin. Our results suggest that the major cytoplasmic chaperone, Hsp90, plays an important role in CD28-mediated T lymphocyte activation.