Immunological Cross‐Reactivity between Electric‐Eel Acetylcholinesterase and Rat‐Tail‐Tendon Collagen

Immunological cross‐reactivity between acetylcholinesterase from the electric organ of the electric eel and rat tail tendon collagen was examined both on the cellular and humoral levels. Guinea pigs immunized with rat tail tendon collagen displayed a strong delayed‐type skin reaction when tested with the elongated acetylcholinesterase preparation (i.e. 14‐S + 18‐S molecular forms). However, when the glubular 11‐S enzyme was tested, almost no cross‐reactivity was obtained. Similarly, guinea pigs immunized with 14‐S + 18‐S preparation exhibited skin sensitization to rat tail tendon collagen. Using a radioimmunoassay, it was observed that ¹²⁵I‐labeled 14‐S + 18‐S acetylcholinesterase binds efficiently to rabbit antiserum elicited against rat tail tendon collagen, whereas ¹²⁵I‐labeled 11‐S enzyme does not bind at all to this antiserum. Similar results were obtained by passive hemagglutination assay. The experiments suggest that 14‐S + 18‐S acetylcholinesterase, but not 11‐S enzyme, which is devoid of the tail structure, has antigenic determinants in common with collagen from rat tail tendon.