ANTICOLLAGEN ANTIBODIES IN SYSTEMIC-SCLEROSIS AND IN PRIMARY RAYNAUDS-PHENOMENON

The frequency and specificity of antibodies to native and denatured co llagens were evaluated in systemic sclerosis (SSc) and in primary Rayn aud's phenomenon (PRP) by direct and competitive ELISA. Antibodies rea ctive with denatured collagen type I (CI) were found in 43 % of the SS c sera, and anti-CIV and anti-CV in 31%. In PRP, anti-CI, anti-CIV and anti-CV antibodies were detected in 8% of patient sera. Anti-CI, anti -CIV and anti-CV antibodies reacted with determinants expressed on the native as well as on the denatured molecule. Anti-CI and anti-CIV wer e cross-reactive; a reactivity with CII and a lower one with CV were d etected. Anti-CV antibodies also reacted with CI and CII and, in a sma ller proportion of cases, with CIV. Anti-collagen antibodies, affinity -purified from blotted collagen IV and V and cyanogen bromide (CBr)-di gested CI, displayed the cross-reactivities shown by inhibition studie s on sera. Moreover, antibodies eluted from a CBr fragment of CI react ed with the other CBr fragments as well. These data show that one-thir d of SSc sera contain antibodies that react with epitopes expressed on native as well as on heat-denatured CI, CII, CIV and CV, and therefor e have the potential to bind collagens in vivo.