Antibodies to different peptides in osteopontin reveal complexities in thevarious secreted forms

We have generated synthetic peptides corresponding to various portions of h uman osteopontin (OPN) and have immunized rabbits and mice with these pepti des to generate polyclonal and monoclonal antibodies specific to human OPN. We then generated six distinct sandwich enzyme-linked immunoabsorbent assa y (ELISA) systems by using different pairs of polyclonal and monoclonal ant ibodies against human OPN. These systems allowed us to detect nor only vari ous isoforms and truncated forms of recombinant OPN, but also the glycosyla ted form of native urinary OPN. Most importantly, tumor-derived OPN was dif ferentially detected by the six ELISA systems. The ELISA systems that we ha ve developed will be useful for clarifying the functional roles for OPN in vivo in various physiologic and pathologic conditions. J. Cell. Biochem. 77 :487-498, 2000. (C) 2000 Wiley-Liss, Inc.