EXACERBATION OF PLASMODIUM-CHABAUDI MALARIA IN MICE BY DEPLETION OF TCR-ALPHA-BETA(-CELLS, BUT NOT TCR-GAMMA-DELTA(+) T-CELLS() T)

3Although gamma delta T cells are found in increased numbers in the sp leens of humans and mice infected with malaria, it is not known if the se cells are necessary components of an effective immune response. The surface phenotype of spleen cells obtained from mice infected with av irulent Plasmodium chabaudi adami or virulent Plasmodium chabaudi chab audi were examined using anti-delta or anti-alpha beta T-cell-specific reagents and flow cytometry. Levels of parasitaemia, red blood cell ( RBC) counts, and survival times were followed in mice depleted of tumo ur necrosis factor (TCR)gamma delta(+) or TCR alpha beta(+) T cells. N umbers of gamma delta T cells increased in the spleens of control anti body-treated infected mice, but not in mice depleted of TCR gamma delt a(+) or TCR alpha beta(+) T cells. Mice depleted of gamma delta T cell s had levels of parasitaemia, RBCs, and survival rates similar to cont rol antibody-treated mice. However, mice depleted of TCR alpha beta(+) T cells had higher levels of parasitaemia, lower RBC counts, and decr eased survival rates. These results indicate that TCR alpha beta(+) bu t not TCR gamma delta(+) T cells play an essential role in host defens e against P. chabaudi infection in mice.