title: B cell response during infection with the MAT a and MAT alpha mating types of Cryptococcus neoformans.
abstract: In the present study, we compared the B cell response of BALB/c and C57Bl/6 mice during Cryptococcus neoformans infection. This response was investigated using virulent serotype D forms of mating types alpha and a (MAT alpha and MAT a). C57Bl/6 mice showed massive (mainly cerebral) infection by both types, while BALB/c were resistant to infection. Some resistance of C57Bl/6 mice was induced by previous immunization with the capsular polysaccharide from MAT alpha. Passive immunization of C57Bl/6 mice with purified antibody (Ab) obtained from capsular polysaccharide-immunized mice also increased resistance to infection. Both mouse strains showed comparable low IgM response to the capsular polysaccharide from MAT alpha, and only C57Bl/6 mice produced IgM to the polysaccharide of MAT a. Comparable levels of different immunoglobulin (Ig) isotypes against capsular components of MAT alpha and MAT a were detected, and the response of C57Bl/6 mice was higher when compared to that of BALB/c mice. FACS analysis indicated an increase in the percentage of a high-granulosity (side-scatter) splenic subpopulation and in the percentage of splenic Gr-1+ cells in infected C57Bl/6 mice. In addition, the percentage of follicular splenic B cells was decreased after C. neoformans infection of C57Bl/6 mice. This response was more pronounced when we investigated infection induced by the MAT a mating type. Taken together, our results indicate that capsular polysaccharide derived from MAT alpha and MAT a types of C. neoformans have a stimulatory effect upon B cells but that there is no correlation between resistance of BALB/c mice and Ab production. However, the increase in resistance of C57Bl/6 mice parallels the production of Abs and a major change in splenic cell populations.
authors.affiliation: Instituto de Microbiologia Professor Paulo de Góes, CCS, Bloco I, Universidade Federal do Rio de Janeiro, Cidade Universitária, Ilha do Fundão, Rio de Janeiro, RJ 21944-570, Brazil.
authors.forename: Adila Regina T Santos
authors.initials: AR
authors.lastname: Rodrigues
authors.forename: Norton
authors.initials: N
authors.lastname: Heise
authors.forename: José Osvaldo
authors.initials: JO
authors.lastname: Previato
authors.forename: Lucia
authors.initials: L
authors.lastname: Mendonça-Previato
authors.forename: Ligia M T
authors.initials: LM
authors.lastname: Peçanha
mesh_terms: D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood; D001402:B-Lymphocytes / Q000276:immunology*; D003453:Cryptococcosis / Q000276:immunology*; D003455:Cryptococcus neoformans / Q000235:genetics / Q000276:immunology*; D004198:Disease Susceptibility; D005260:Female; D007114:Immunization; D007075:Immunoglobulin M / Q000096:biosynthesis / Q000097:blood; D018655:Lymphocyte Count; D008297:Male; D000072235:Mating Factor; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D010455:Peptides / Q000737:chemistry / Q000502:physiology; D011134:Polysaccharides / Q000276:immunology; D013154:Spleen / Q000276:immunology
chemical_list: D000913:Antibodies, Protozoan; D007075:Immunoglobulin M; D010455:Peptides; D011134:Polysaccharides; D000072235:Mating Factor