IMMUNOPATHOLOGICAL ASPECTS OF PLASMODIUM-BERGHEI INFECTION IN 5 STRAINS OF MICE .1. IMMUNE-COMPLEXES AND OTHER SEROLOGICAL FEATURES DURING THE INFECTION

Abstract

Circulating immune complex development was studied in mice of the BALB/c, A/J, OF1, CBA and C57Bl strains infected with P. berghei. Complexes were evaluated in relation to levels of parasitemia, soluble antigen, specific antibody and C3 [complement component 3]. Susceptibility to infection was greatest in BALB/c, A/J and OF/1 mice. The maximum parasitemia was 30% in CBA and 70% in all other strains. Soluble antigen levels paralleled those of parasitemia. Specific antibody was detected in all strains, but the titer continued to rise throughout the infection only in CBA mice. Circulating immune complexes occurred in mice of all strains from day 6; the level fell after day 9 in C57Bl, whereas it was maintained in CBA mice. Immune complex development was associated with marked C3 level depression in all except CBA mice, in which a transient reduction was followed by recovery. Partial characterization of the complexes showed that IgM-containing complexes appeared earliest and reached highest levels in BALB/c mice while in CBA mice, IgM complexes were found in lesser amounts and the level fell in late infection. IgG complexes rose throughout infection in CBA and fell in later stages in BALB/c and C57Bl mice. In nude BALB/c mice, immune complexes were usually not detectable and only low levels of IgM antibody were produced. Differences in mortality pattern could not be related to any single serological factor.