oxazolone and Malaria

The suppression of the contact sensitivity of oxazolone in murine malaria is shown to be mediated by non-specific T suppressor cells, but to a different extent in infection caused by two different species of parasite. Depletion of T suppressor cells in vivo and/or anti-Thy 1.2 treatment in vitro indicated that in mice infected with P. berghei the suppressor effect was largely mediated by T cells. By contrast, in mice infected with a lethal strain of P. yoelii it was only partly due to T cells; B suppressor cells and/or macrophages may also be involved. However, depletion of T suppressor cells in vivo had no effect on the course of the parasitaemia or on the survival time. Therefore, we postulate that this kind of non-specific immunosuppression cannot be regarded as a major cause of lethality.

Topics: Animals; B-Lymphocytes; Dermatitis, Contact; Female; Immune Tolerance; Lymphocyte Depletion; Malaria; Mice; Mice, Inbred Strains; Oxazolone; Plasmodium berghei; T-Lymphocytes; T-Lymphocytes, Regulatory

A comparative study of non-specific immunosuppression by malaria has been carried out in five situations: in both unvaccinated and vaccinated mice infected with the lethal Plasmodium yoelii or the lethal Plasmodium berghei, and in the unvaccinated non-lethal P. yoelii infection. Spleen cells showed a suppressive effect on the normal blastogenic response to mitogens. This suppression was strongest in the mice vaccinated before infection with the lethal P. yoelii and in those infected with non-lethal P. yoelii, suggesting that the suppressive effect did not interfere with recovery. Silica, anti-Thy-1, and indomethacin treatment suggested that this suppression was caused by macrophages. However, the plaque-forming cell response to sheep RBC in vivo was suppressed equally in every case at the peak of the parasitaemia, whereas the suppression of contact sensitivity to oxazolone was strongest in mice with fatal infections. We suggest that different suppressor mechanisms operate in malaria, some being harmful to the host and others possibly beneficial.

Topics: Animals; Antibody Formation; Female; Hemolytic Plaque Technique; Hypersensitivity, Delayed; Immune Tolerance; Malaria; Male; Mice; Mice, Inbred BALB C; Mice, Inbred C57BL; Oxazolone; Plasmodium berghei; Spleen

Topics: Animals; Antibody Formation; Lymphocyte Activation; Malaria; Mice; Mice, Inbred CBA; Oxazolone; Plasmodium berghei; Spleen; T-Lymphocytes