Differential T cell responses to Plasmodium chabaudi chabaudi in peripheral blood and spleens of C57BL/6 mice during infection.

The definition of the immune status of a person is often taken as the responses obtained from lymphocytes isolated from peripheral blood. We therefore analyzed in a mouse model of Plasmodium chabaudi chabaudi the response of T lymphocytes taken from peripheral blood and compared it with the spleen during and after a primary erythrocytic infection. Using limiting dilution conditions, no malaria-specific T cell responses could be measured in the peripheral blood for up to 21 days after infection with P. chabaudi, whereas T cells responding to malaria Ag were readily detected in the spleen. This was true for T cells providing help and for those producing IFN-gamma. After clearance of the parasitemias to subpatent levels (75 days), qualitatively similar T cell responses were found in both compartments of the immune system, i.e., the Th cell response predominated over the inflammatory response. These data suggest that during an active infection with Plasmodium, T cell responses in peripheral blood are not necessarily indicators of the immune status.