Heat Shock Protein 90 Expression in Epstein-Barr Virus-Infected B Cells Promotes T-Cell Proliferation In Vitro

The aim of this study was to elucidate the in vitro response of T cells to Epstein-Barr virus (EBV)-infected B cells and to determine whether EBV-induced heat shock proteins (HSPs) might serve as T-cell stimulants. Cytofluorometric analysis revealed HSP90 cell surface expression in 12% of the EBV-immortalized B-cell population in all four of the B-cell lines tested. HSP27, HSP60, and HSP70 were not detected on the cell surface by cytofluorometry in these same B-cell lines. HSP90 and HSP60, but not HSP70 or HSP27, were detected on the cell surface after I cell surface labeling and immunoprecipitation with anti-human HSP monoclonal antibodies. In vitro kinetic studies indicated that T cells increased at least twofold by day 11 postinfection in cultures of EBV-seronegative peripheral blood lymphocytes infected with EBV, whereas percentages of T cells in these same cultures either decreased slightly or remained relatively unchanged in response to EBV infection. Addition of anti-human HSP90 monoclonal antibody to the EBV-infected lymphocyte cultures inhibited T-cell expansion by 92%. The inhibition of T-cell expansion by anti-HSP90 antibody was reversed upon treatment with exogenous HSP90. Taken together, these results indicate that HSP90 played an important role in the stimulation of T cells during EBV infection of B cells in vitro and may serve as an important immunomodulator of T cells during acute EBV infection.