Characterization of the spleen B-cell compartment at the early and late blood-stage Plasmodium chabaudi malaria.
Polyclonal B-cell activation is a feature of the early spleen cell response to blood-stage Plasmodium chabaudi malaria. Immunity to blood-stage malaria is guaranteed by the generation of B cells able to produce parasite-specific antibodies mainly from the immunoglobulin (Ig)G2a isotype. In the present study, we characterized the spleen B-cell compartment during blood-stage P. chabaudi infection. The numbers of B220(+) and B220(LOW) CD138(+) (plasma) cells increased sharply between days 4 and 7 post-infection (p.i.). At this time B220(+) cells expressed surface (s)IgM, but nearly all B220(LOW) CD138(+) cells showed concomitantly intracellular (i)IgM and IgG2a. Both follicular and marginal zone B cells were activated expressing high amounts of CD69. At day 40 p.i., B220(LOW) CD138(+) cell population was still increased but, differently from acute infection, 61.1% of these cells were positive for iIgG2a while only 14.2% expressed iIgM. Moreover, at days 20 and 40 p.i., 29.2% and 13.0% of B220(+) cells expressed sIgG2a, respectively. According to cell size and expression of CD80, CD86, CD11b, CD44 and CD38, B220(+) sIgG2a(+) cells had a phenotype characteristic of activated/memory B cells. Furthermore, 14.1% of B220(+) sIgG2a(+) cells at day 30 p.i. expressed a marginal zone B-cell phenotype. Importantly, B cells from 40-day-infected mice were very efficient in presenting parasite antigens leading to proliferation of both CD4(+) and CD8(+) cells. Our results contribute for understanding the dynamics of B cells during P. chabaudi infection, underlying the mechanisms of antigen presentation and antibody production, which are essential for the acquisition of protective immunity against malaria.
Castillo-Méndez
S I
SI
Department of Immunology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil. sheylacastillo@yahoo.com
Zago
C A
CA
Sardinha
L R
LR
Freitas do Rosário
A P
AP
Alvarez
J M
JM
D'Império Lima
M R
MR
D000818:Animals; D000913:Antibodies, Protozoan / Q000096:biosynthesis; D017951:Antigen Presentation / Q000276:immunology; D016175:B-Lymphocyte Subsets / Q000276:immunology* / Q000469:parasitology / Q000473:pathology; D002478:Cells, Cultured; D005260:Female; D016130:Immunophenotyping; D018655:Lymphocyte Count; D008288:Malaria / Q000097:blood / Q000276:immunology* / Q000469:parasitology*; D051379:Mice; D008810:Mice, Inbred C57BL; D018512:Parasitemia / Q000276:immunology / Q000469:parasitology / Q000473:pathology; D010950:Plasma Cells / Q000276:immunology / Q000469:parasitology / Q000473:pathology; D016788:Plasmodium chabaudi / Q000254:growth & development / Q000276:immunology*; D013154:Spleen / Q000166:cytology / Q000276:immunology* / Q000473:pathology
D000913:Antibodies, Protozoan