Parasite-specific IgM plays a significant role in the protective immune response to asexual erythrocytic stage Plasmodium chabaudi AS infection.
A comparison of Plasmodium chabaudi AS infection in BALB/c and BALB/c IgM-deficient mice demonstrated a protective role for IgM during infection. IgM-/- mice, unlike microMT mice, display competent B cell humoral immune responses. Increased susceptibility of IgM-/- mice was demonstrated by increased mortality, an advanced ascending infection and higher peak parasitaemia, as well as enhanced anaemia and weight loss compared with wild-type mice. The recrudescent parasitaemias were also higher in the IgM-/- mice. Early specific IgM production in P. chabaudi-infected wild-type mice was followed by IgG1 and IgG2a production, while IgG1 and IgG2a production in IgM-/- mice was preceded by specific IgD production. No protective role for natural IgM against P. chabaudi AS infection was detected as passive transfer of naïve WT serum into IgM-/- mice did not alter the disease outcome or reduce parasite numbers. Passive transfer of WT antiserum, containing predominantly specific IgM, into IgM-/- mice delayed the ascending parasitaemia and reduced mortality. Similarly, coating parasitized red blood cells with WT antiserum, but not IgM-/- antisera, prior to infection also slightly delayed the ascending acute parasitaemia. Specific IgM therefore plays an important role in the limitation of parasite replication during asexual erythrocytic P. chabaudi AS infection.
Couper
K N
KN
Department of Immunology, Strathclyde Institute for Biomedical Sciences, University of Strathclyde, 27 Taylor Street, Glasgow, UK. kevin.couper@lshtm.ac.uk
Phillips
R S
RS
Brombacher
F
F
Alexander
J
J
D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood / Q000276:immunology; D000918:Antibody Specificity; D004912:Erythrocytes / Q000469:parasitology; D007106:Immune Sera / Q000008:administration & dosage / Q000276:immunology; D007116:Immunization, Passive; D007075:Immunoglobulin M / Q000097:blood / Q000276:immunology*; D008288:Malaria / Q000276:immunology* / Q000469:parasitology; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D018345:Mice, Knockout; D018512:Parasitemia / Q000276:immunology* / Q000469:parasitology; D016788:Plasmodium chabaudi / Q000276:immunology*
D000913:Antibodies, Protozoan; D007106:Immune Sera; D007075:Immunoglobulin M