Functional properties of T lymphocytes and their subsets in cytomegalovirus mononucleosis.

Cytomegalovirus (CMV) mononucleosis is associated with diminished lymphocyte responses to mitogens and herpes virus antigens, and a reversal in the normal ratio of helper-inducer (OKT4-positive) to cytotoxic-suppressor (OKT8-positive) cells. In this report, we investigate the proliferative and cytotoxic functions of lymphocyte subpopulations from patients with CMV mononucleosis. Both mitogen responsiveness and the ability to generate cytotoxic lymphocytes against allogeneic Laz 156 cells in vitro were markedly diminished. Mononuclear cells enriched for OKT8+ lymphocytes showed little or no responsiveness to Con A; cells enriched for OKT4+ lymphocytes were considerably more responsive. During CMV mononucleosis, the predominant T cell subset is a hyporesponsive OKT8+ cell. In vitro culture of peripheral blood lymphocytes, however, resulted in a selective loss of OKT8+, OKIa+ cells, so that the remaining T cell population was composed primarily of Con A-responsive OKT4+ cells. Convalescence was associated with the return of OKT8+ responsiveness to Con A, a greater stability of OKT8+ cells during culture, and the partial recovery of ability to develop cytotoxic lymphocytes after in vitro sensitization.