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B cell response during infection with the MAT a and MAT alpha mating types of Cryptococcus neoformans

Adila Regina T Santos Rodrigues1, Norton Heise, José Osvaldo Previato

  • 1Instituto 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.

Microbes and Infection
|February 18, 2005
PubMed

Insights

BALB/c mice resist Cryptococcus neoformans infection, unlike susceptible C57Bl/6 mice. Antibody production and splenic cell changes correlate with increased resistance in C57Bl/6 mice, suggesting a role for B cell response in cryptococcosis immunity.

Area of Science:

  • Immunology
  • Microbiology
  • Infectious Diseases

Background:

  • Cryptococcus neoformans is a significant fungal pathogen causing cryptococcosis.
  • Host immune responses, particularly B cell activity, play a crucial role in controlling fungal infections.
  • Different mouse strains exhibit varying susceptibility to C. neoformans infection.

Purpose of the Study:

  • To compare the B cell response in BALB/c and C57Bl/6 mice during Cryptococcus neoformans infection.
  • To investigate the role of capsular polysaccharides from different mating types (MAT alpha and MAT a) in modulating the immune response.
  • To assess the correlation between antibody production, B cell population changes, and host resistance.

Main Methods:

  • Infection of BALB/c and C57Bl/6 mice with virulent C. neoformans serotype D (MAT alpha and MAT a).
  • Immunization and passive immunization strategies using capsular polysaccharide and antibodies.
  • Flow cytometry (FACS) analysis of splenic B cell subpopulations (Gr-1+ cells, high-granulosity cells, follicular B cells).
  • Measurement of immunoglobulin (IgM, IgG) responses to capsular polysaccharides.

Main Results:

  • BALB/c mice demonstrated resistance to C. neoformans infection, while C57Bl/6 mice showed massive, often cerebral, infections.
  • Previous immunization with MAT alpha capsular polysaccharide or passive antibody transfer increased resistance in C57Bl/6 mice.
  • C57Bl/6 mice exhibited higher immunoglobulin responses to C. neoformans capsular components compared to BALB/c mice.
  • Infection led to increased Gr-1+ and high-granulosity splenic cells and decreased follicular B cells in C57Bl/6 mice, more pronounced with MAT a.

Conclusions:

  • Capsular polysaccharides from C. neoformans MAT alpha and MAT a stimulate B cells.
  • There is no direct correlation between BALB/c mouse resistance and antibody production.
  • Increased resistance in C57Bl/6 mice is associated with antibody production and significant alterations in splenic B cell populations.

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