Immediate hypersensitivity responses in flatfish.

Fungal extracts that precipitate with human C-reactive protein caused immediate erythema on subdermal injection into marine flatfish. Only species with calcium-dependent serum precipitins to these fungi showed skin reactions. Immediate hypersensitivity in a nonreactive species could be induced after injection with serum from reactive species. The transferable serum factor (or factors) was heat sensitive.