Loss of circulating T lymphocytes with normal levels of B and 'null' lymphocytes in Thai adults with malaria.

Peripheral blood mononuclear cells from forty-nine Thai adults infected with either Plasmodium falciparum or Plasmodium vivax were examined in order to determine the percentage of T, B, and Fc-receptor-bearing cells present. In comparison to healthy controls, both the percentage and concentration of peripheral T cells were decreased in the malaria-infected individuals as assessed by formation of rosettes with sheep red blood cells. The percentage of peripheral B cells was increased but their concentration was unchanged, as assessed by two techniques: the presence of surface immunoglobulin and the presence of a complement receptor. Both the percentage and concentration of lymphocytes bearing Fc receptors were unchanged in infected individuals. Finally, calculation of the changes in 'null' cells (defined either as non-T, non-B lymphocytes or as non-T, non-B, non Fc-receptor-bearing lymphocytes) revealed an increase in the 'null' cell percentage but a decrease in the absolute number of 'null' cells. These data indicate that in adult Thai patients naturally infected with malaria, there is a real loss of circulating T lymphocytes with no real change in B, Fc-receptor-bearing, or 'null' lymphocytes.