Demonstration of a unique antigenic specificity for the collagen alpha1 (II) chain from cartilaginous tissue.

The rabbit antibody response to native collagen (chain composition [alpha1(II)3) from cartilaginous tissue, has been examined by agglutination assays, gel diffusion, haemagglutination-inhibition studies, and immunoadsorption. The results show that the rabbit antibody response to the cartilage-type collagen is characterized by considerable reactivity to both helical [alpha1(II)]3 as well as alpha1(II) chains. This is in contrast to the rat antibody response to the same antigens where titres are generated to largely helical antigenic determinants. Similarly to the rat response, rabbit antibodies to [alpha(II)]3 exhibit no strong cross-reaction with the genetically distinct [alpha(I)]2ALPHA2 collagen or its component chains. Strong cross-reactions were, however, observed between bovine and chick alpha1(II) chains. One of the major antigenic sites on [alpha1(II)]3 collagen appears to reside in the sequence represented by CB-11, a peptide derived from the helical portion of the [alpha1(II)]3 molecule after cyanogen bromide cleavage. The data, however, are compatible with the presence of other antigenic determinants which are probably located in the amino- and carbocy-terminal portions of the molecule.