IN-VIVO BINDING OF HUMAN INTER-ALPHA-TRYPSIN INHIBITOR-FREE HEAVY-CHAINS TO HYALURONIC-ACID

In vivo binding of human inter-alpha-trypsin inhibitor to hyaluronate was investigated by immunoelectrophoretic techniques. Pathological syn ovial fluids and follicular fluids both contain high concentrations of soluble hyaluronate. Heavy chain epitopes of inter-alpha-trypsin inhi bitor were firmly associated with the hyaluronate in synovial fluid an d follicular fluid. The hyaluronate-bound inter-alpha-trypsin inhibito r epitopes did not cross-react immunologically with bikunin. Several h yaluronate-bound inter-alpha-trypsin inhibitor fragments with molecula r masses in the range 120 000-30 000 Da were demonstrated by immunoblo tting. Heavy chain 1 of inter-alpha-trypsin inhibitor was shown to ass ociate with hyaluronate by amino acid sequence analysis of isolated hy aluronate-bound proteins. These data indicate that in vivo metabolism of inter-alpha-trypsin inhibitor takes place in pathological synovial fluid and in ovarian follicular fluid shortly before ovulation.