Isolation of a phosphorylcholine-containing component from the turbot tapeworm, Bothriocephalus scorpii (Müller), and its reaction with C-reactive protein.

A fraction isolated by electrofocusing (pI 4.2) from a saline extract of the turbot parasite, Bothriocephalus scorpii, contained choline and precipitated with a teleost C-reactive protein (CRP) and a phosphorylcholine-binding Balb/c mouse myeloma protein, TEPC-15. Non-dialysable products released from cultured tapeworms also precipitated with the phosphorylcholine-specific precipitins. Ca2+ was required for precipitation with CRP and immunodiffusion lines were confluent with pneumococcal C-polysaccharide and a fungal C substance. Intradermal injection of the phosphorylcholine-containing fraction caused an immediate erythema reaction in all mature turbot tested. The skin reaction is though to be related to the amount of circulating CRP and this protein was present in sera fro all nature turbot giving a positive skin response. There is no evidence for CRP being toxic to the tapeworms and the possibility is discussed that the worms exploit the host CRP for their own survival.