Related Experiment Videos
Differences in Cryptococcus neoformans capsular polysaccharide structure influence assembly of alternative complement
R G Washburn1, B J Bryant-Varela, N C Julian
1Department of Medicine, Bowman Gray School of Medicine, Winston-Salem, NC 27103.
Molecular Immunology
|April 1, 1991
Summary
Cryptococcus neoformans serotypes B and C bind fewer complement components, hindering the immune response. Modifying their capsular polysaccharide improves complement binding, suggesting a target for treating fungal infections.
Area of Science:
- Immunology
- Mycology
- Microbiology
Background:
- Cryptococcus neoformans is an opportunistic fungal pathogen.
- The alternative complement pathway plays a role in innate immunity against fungal infections.
- Different serotypes of C. neoformans exhibit varying susceptibility to host defenses.
Purpose of the Study:
- To investigate the binding of complement components C3 and Factor B to different serotypes of C. neoformans.
- To determine the role of capsular polysaccharide structure in complement component binding.
- To understand the implications for the alternative complement pathway's efficiency against C. neoformans.
Main Methods:
- Measurement of complement component binding using fresh nonimmune human serum.
- Comparison of binding levels between C. neoformans serotypes A, B, C, and D.
- Chemical modification of capsular polysaccharide using the Smith degradation procedure.
Main Results:
- Serotypes B and C (C. neoformans var. gattii) bound approximately half the amount of C3 and Factor B compared to serotypes A and D (C. neoformans var. neoformans).
- Smith degradation of capsular polysaccharide resulted in similar C3 binding across all four serotypes.
- The side chain substitution of capsular polysaccharide influences complement component binding.
Conclusions:
- High side chain substitution in C. neoformans var. gattii capsular polysaccharide leads to inefficient alternative pathway C3 convertase assembly.
- Inefficient complement component binding to serotypes B and C may contribute to treatment challenges for infections caused by these organisms.