Trypanosoma gambiense: Blocking ability of parasite and macrophage homogenates on attachment during phagocytosis

Circulating immune complexes in Fièvre boutonneuse

Circulating immune complexes (CIC) occurred in 36% of a group of 25 patients with Fièvre boutonneuse. CIC were present only in the first week of the disease and there was no evidence of other humoral immunological abnormalities or alterations of the coagulation factors studied. The presence of CIC was not associated with a more severe clinical manifestation or with symptoms or tissue injuries. It is considered that CIC do not play a major role in Fièvre boutonneuse.

Plasmodium berghei malaria: blockage by immune complexes of macrophage receptors for opsonized plasmodia

Immune complexes produced in vitro by mixing immune serum and soluble Plasmodium berghei antigens and immune complexes precipitated from serum of acutely infected rats blocked macrophage receptor sites for opsonized plasmodia. The immune complexes were precipitated from acute-phase serum, using polyethylene glycol, and their composition was determined by using a Raji cell immunofluorescence assay. The immune complexes contained immunoglobulin G (IgG), IgM, and malarial antigens. These results indicate that immune complexes in the serum of acutely infected animals may protect the plasmodia from the activities of macrophages.

Adoptive transfer of variant-specific resistance to Trypanosoma rhodesiense with B lymphocytes and serum

Mice survive an otherwise lethal infection with Trypanosoma rhodesiense if previously inoculated with irradiated organisms. This resistance demonstrates immunological specificity, since even animals inoculated with irradiated trypanosomes were killed when challenged with trypanosomes of a nonhomologous or variant antigenic type. This resistance could be transferred to syngeneic recipients with serum or B lymphocytes. T lymphocytes had no capacity to transfer resistance. Although mice were protected from active infection on challenge at least 25 days after inoculation of irradiated organisms, this resistance could be transferred with spleen cells for only 10 days after immunization. Resistance could be transferred with serum for a minimum of 25 days after immunization. These studies implicate an antibody-mediated mechanism as having a major role in resistance to T. rhodesiense infections.