The effects of human cytomegalovirus challenge in vitro on subpopulations of T cells from seronegative donors.

Purified T cells from seronegative donors were challenged with human cytomegalovirus (CMV) and assayed for response to the mitogen phytohemagglutinin (PHA) administered at various times after virus challenge. Cells were hyporesponsive to PHA added up to 6 h postinfection, while cells challenged with ultraviolet (UV)-inactivated CMV showed normal PHA responses. T-cell populations showed a complete inversion of helper/suppressor ratios by 6 h of infection, as determined by indirect immunofluorescence using the monoclonal antibodies OKT4 and OKT8. This increased proportion of suppressor cells was functionally demonstrable in an autologous one-way mixed lymphocyte reaction (AMLR).