FIG 1 .

Chitin particles generate C3a in vivo and via the alternative pathway in vitro. Chitin particles or Aspergillus antigens were coincubated with plasma and neutralizing antibodies. C3a levels were determined by ELISA. Chitin induced C3a generation in human plasma (n = 3) (A) and in mouse plasma (n = 3) (B). (C) Chitin induces C3a generation in human plasma via the alternative pathway. IgG1, isotype control antibody (Ab); αC1q, C1q neutralizing Ab; αFactorB, factor B neutralizing Ab (n = 3). (D) Chitin particles or PBS was administered intratracheally (i.t.). Within 24 h, perfused lung homogenate was obtained and C3a levels were determined by ELISA (n = 5). Values are presented as means ± standard errors of the means (SEM); *, P < 0.05 versus PBS.