Calreticulin, a potential cell surface receptor involved in cell penetration of anti-DNA antibodies

A 50-kDa protein was purified as a potential receptor, using an affinity ma trix containing biotinylated F14.6 or H9.3 anti-DNA mAbs derived from autoi mmune (New Zealand Black x New Zealand White)F-1 mouse and membrane extract s from cells. This protein was identified as calreticulin (CRT) by microseq uencing. Confocal microscopy and FRCS analysis showed that CRT was present on the surface of various cells. CRT protein was recognized by a panel of a nti-DNA mAbs in ELISA. The binding of F14.6 to lymphocytes and Chinese hams ter ovary cells was inhibited by soluble CRT or SPA-600. Thus, the anti-DNA mAbs used in this study bound to CRT, suggesting that CRT may mediate thei r penetration into the cells and play an important role in lupus pathogenes is.