[Alloantibody to proteoglycan induced by osteochondral homotransplantation in rabbits]

The role of possible alloantigenicity of matrix proteoglycan (PG) in the osteochondral homotransplantation of knee joints was studied in rabbits. The incidence of acute rejection could be reduced by removing marrow tissues from grafts, but 5 of 25 recipients produced IgG anti-PG, even though the rabbits immunized with pooled PG in Freund's complete adjuvant failed to produce antibody. The reactivity of antibody in grafted animals was restricted to a core protein fraction of 600k dalton and to a relatively small fraction of pooled PG. No reactivity with completely glycosylated PG was detected. Grafts of anti-PG positive recipients were stained weakly with toluidine blue and exhibited minor degenerative changes of cartilage cells. These findings suggest that either glycosylation or sulfation of PG is impaired in the grafts and that such defective PG is antigenic to the host.