Effects of strain variation, serotype, and structural modification on kinetics for activation and binding of C3 to Cryptococcus neoformans.
AUTOR(ES)
Young, B J
RESUMO
Incubation of encapsulated cells of Cryptococcus neoformans in normal human serum leads to activation of the alternative complement pathway and deposition of opsonic fragments of C3 into the capsule. We determined whether the variation in capsular structure that occurs among the four major cryptococcal serotypes was reflected in the kinetics for activation and binding of C3. We also examined the effects on activation kinetics of de-O-acetylation or periodate oxidation of the capsule. Binding kinetics were characterized in terms of the time required to deposit 5% of the maximal amount of C3 on the yeast (t5%), the first-order rate constant for amplification of C3 deposition (k'), and the maximum amount of C3 that could be deposited in the capsule (C3max). Our results showed that variations in the capsular structure that characterized each serotype had no significant influence on C3max but that the rate of C3 deposition depended significantly on the serotype. C3 accumulated at a higher rate on cells of serotypes A and D than on cells of serotypes B and C. There was a significant correlation between capsular volume and C3max, although the relationship was not linear. Periodate treatment of encapsulated cryptococci of all four serotypes led to decapsulation. Periodate-oxidized encapsulated cells displayed kinetics for activation and binding of C3 that were identical to kinetics observed with nonencapsulated cryptococci. Finally, de-O-acetylation led to a significant but relatively minor increase in C3max.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=280946Documentos Relacionados
- In vivo complement activation and binding of C3 to encapsulated Cryptococcus neoformans.
- Kinetic analysis of the amplification phase for activation and binding of C3 to encapsulated and nonencapsulated Cryptococcus neoformans.
- Strain variation in phagocytosis of Cryptococcus neoformans: dissociation of susceptibility to phagocytosis from activation and binding of opsonic fragments of C3.
- Contribution of antibody in normal human serum to early deposition of C3 onto encapsulated and nonencapsulated Cryptococcus neoformans.
- Secretion of the C3 component of complement by peritoneal cells cultured with encapsulated Cryptococcus neoformans.