Characterization of recombinant type II collagen: arthritogenicity and tolerogenicity in DBA/1 mice

Recombinant human type II collagen (rhCII) was produced using both the HT10 80 mammalian cell expression system (rhCII(ht)) and a baculovirus expressio n system (rhCII(bac)). The biosynthesis of CII requires extensive post-tran slational modifications, such as the hydroxylation of prolyl and lysyl resi dues and glycosylation of hydroxylysyl residues. Amino acid analyses indica ted that the rhCII(bac) was adequately hydroxylated at prolyl residues but underhydroxylated at lysyl residues and underglycosylated compared with tis sue-derived hCII, while rhCII(ht) was hyperhydroxylated and hyperglycosylat ed at lysyl residues. When the murine collagen-induced arthritis (CIA) mode l was used to investigate the immunological properties of the two forms of recombinant CII, each induced a high incidence of arthritis following immun ization of susceptible mice when emulsified with complete Freund's adjuvant (CFA). However, the severity of the arthritis, as assessed by the number o f affected limbs, was significantly higher in mice immunized with rhCIIht t han in mice immunized with rhCIIb(bac). These data indicate that the degree of hydroxylysine glycosylation may play a role in the induction of the art hritogenic response to CII. Each of the recombinant collagens was comparabl e to tissue-derived hCII in their ability to induce tolerance and suppress arthritis when given as intravenous or oral tolerogens. Taken together, our data suggest that recombinant CII can be prepared in adequate amounts for therapeutic uses and that the material is immunologically comparable to tis sue-derived hCII when used to induce tolerance.