Limiting dilution analysis of the T cell response to Plasmodium chabaudi chabaudi in mice.

A limiting dilution assay system was developed in order to measure the in-vitro T cell response to antigens of the erythrocytic stages of Plasmodium chabaudi. The conditions of the assay are such that only CD4+ T cells are able to respond. The assay allows the determination of the frequencies of T cells which proliferate and/or which develop into helper cells for antibody production during a primary infection. A specific response from splenic T cells can be measured as early as 7 days after infection, and is still significant 3 months after injection of P. chabaudi. At all times the frequency of proliferating cells was greater than the precursor frequency of T helper cells. This suggests that a proportion of CD4+ T cells in this assay, although they respond to malarial antigen, do not develop into helper cells for antibody production. This limiting dilution assay will be a useful method by which to evaluate the functional heterogeneity of the CD4+ T cell response to malaria antigens.