Abstract

PARRA, Claudia; GONZALEZ, John Mario; CASTANEDA, Elizabeth  and  FIORENTINO, Susana. Anti-glucuronoxylomannan IgG1 specific antibodies production in Cryptococcus neoformans resistant mice. Biomédica [online]. 2005, vol.25, n.1, pp.110-119. ISSN 0120-4157.

Introduction. Cryptococcus neoformans is a ubiquitous fungus which has been shown to be responsible for infections in individuals with impaired cell mediated immunity, such as patients infected with human immunodeficiency virus (HIV). C. neoformans has a polysaccharide capsule composed of glucuronoxylomannan (GXM), which acts as a major virulence factor and is considered to be a thymus independent type-2 antigen (TI-2). Objective. To study the production kinetics of IgG subclasses specific for GXM, the cross reactive antibodies to Streptococcus pneumoniae polysaccharide and to determine spleen B cell subpopulations in murine models of cryptococcosis with different susceptibilities to the infection. Materials and methods. Antibodies were detected by ELISA at different time intervals after C. neoformans infection in moderately resistant (Balb/c), highly resistant (CBA/j) and susceptible (C57BL/6) mouse strains. B cells subpopulations were determined by flow cytometry analysis. Results. Early production of IgG₁, described as protector antibodies, coincided with a decrease of the number of C. neoformans colony forming units (CFU) in the lungs. Polysaccharide cross-reactive antibodies were detected in the three mouse strains, and were highest in the susceptible strain (C57BL/6), which showed the highest proportion of splenic CD5⁺ B lymphocytes. In contrast, CBA/J mice showed the highest levels of CD43⁺ B. Conclusions. These findings suggest that IgG₁ antibodies specific for GXM, are implicated in host protection against C. neoformans infection, and might be regulated by CD43⁺ cells. They also suggest that cross reactivity antibodies are not important in the protection of C. neoformans infection.

Keywords : Cryptococcus neoformans; glucuronoxylomannan; cross-reactive antibodies; IgG subclasses.

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