Activated T-cells with suppressor/cytotoxic phenotype in acute Toxoplasma gondii infection.

The mononuclear cells in the peripheral blood of 17 adults with acute phase toxoplasmosis were characterized with monoclonal antibodies. The absolute number of lymphocytes was increased by the presence of high numbers of T-cells with a surface phenotype of T-cytotoxic/suppressor cells (OKT3+, OKT8+). Shortly after the onset of the infection these cells expressed activation antigens (OKT10+, OKIa+). These changes were more pronounced in patients with lymphadenopathy, but were also present in those without symptoms of the disease. The activation antigens disappeared in the first weeks after onset of the disease but the reversed OKT4/OKT8 ratio persisted for 2 to 4 months. It generally normalized in parallel with clinical recovery of the patients. In one patient, however, a reversed OKT4/OKT8 ratio was present for more than 1 year after the disappearance of the symptoms.