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It is unclear what actually induces eosinophil degranulation in vivo. We examined eosinophil cationic protein (ECP) release from normal human eosinophils (Eos) in response to C3a and C5a. C3a and C5a induced remarkable ECP release when Eos were preincubated with cytochalasin B. ECP release induced by C3a or C5a was greater than that induced by PAF at a concentration of 10^––7M. The ED₅₀ for ECP release was 3 × 10^––8M and 3 × 10^––9M for C3a and C5a, respectively. C3a or C5a elicited a rapid and transient rise in [Ca²⁺]_i. These results suggest that C3a and C5a may contribute to hypersensitivity diseases by inducing eosinophil degranulation.

Suspended particulate matter (SPM), suspended in the polluted environmental atmosphere, are perpetually inhaled into the human body and are considered to have profound effects on human health. This study investigated the enhancing effect of SPM on the IgE antibody production in mice. The IgE antibody responses in mice immunized with intranasal administration of ovalbumin (OA) plus SPM at 3-week intervals were higher than responses in the animals immunized with OA alone. When the dose of OA administered as an antigen was 0.25 μg, the time course and magnitude of enhancement by SPM was comparable to those by killed Bordetella pertussis, a common adjuvant. SPM had an enhancing effect on IgE antibody production even in a small dose such as 0.25 μg administered at 3-week intervals. The possibility cannot be excluded that the natural exposure of humans to SPM in the environmental atmosphere may explain the high prevalence rate of allergic rhinitis caused by pollens in polluted districts in Japan.