Quantitative estimation of suppressor/cytotoxic and helper T cells during acute and chronic Plasmodium berghei infection.

In the present study, the percentage of lymphocyte subpopulations and their relation to T cell subsets was estimated during acute and chronic Plasmodium berghei malaria. During acute infection, a decreased percentage of T lymphocytes was observed, whereas no change was observed during chronic infection. However, no change in the percentage of B cells was observed in both types of infection. The T cell population was characterized by an increased percentage of T suppressor cytotoxic (CD8+) cells and a decreased percentage of T helper cells (CD4+) during acute infection. This resulted in an inversion of the CD8+/CD4+ cell ratio. During chronic infection no change in the CD8+ cell percentage was observed; however some increase in CD4+ cell percentage was observed in later stages. Thus failure of the immune system to overcome acute infection may be due to an increase in T suppressor cells, and maintenance of parasites at subpatent levels during chronic infection may involve the normal CD8+/CD4+ cell ratio with some increase in CD4+ cells.