Immunochemical cross-reactions between pentraxins of different species

Monospecific antisera were raised by immunization with pentraxins, C-reactive protein (CRP) or serum amyloid P component (SAP), that had been isolated from man and a number of different vertebrate species. These antisera were used to test sera or serous fluids from a range of other vertebrate species and also some invertebrates. Cross-reactions between species were comparatively rare but were seen among primates and among ruminants. There was also cross-reactivity between these two groups. Antisera to plaice pentraxins did not react with sera from higher vertebrates but did recognize antigens in sera from other flat fish. No cross-reactivity was observed between CRP and SAP either within or between species despite the known homologies of amino acid sequence and similarities of structure within the family. Several reactions occurred with sera in which either CRP or SAP had previously not been sought or in which only preliminary investigations had been performed. The proteins detected were: CRP in goat, cow, sheep, cat and lemon sole; SAP in monkey and dab. These findings significantly extend the range of species in which pentraxins are known to be present.