[Cartilage transplantation in the area of the head-neck: comparative study of HLA class II antigen induction to chondrocytes in various culture systems].

Autologous and homologous cartilage grafts are often used in reconstructive head and neck surgery. Unfortunately, sometimes the outcome of such operations is endangered by graft rejection or resorption. Among other reasons, immunological reactions with HLA class II antigen expression are thought to be involved at least in failures of vitally grafted cartilage. Up to now, only one case of class II antigen expression in a cartilage graft "in vivo" has been reported. Nevertheless, it has already been demonstrated that stimulated cartilage cells are able to express "in vitro" class II antigens if grown in monolayer cultures. However, it has also repeatedly been shown that chondrocytes reveal strong dedifferentiating features if cultured in monolayers. Therefore, it was the aim of this study to examine whether isolated and stimulated chondrocytes also express class II antigens if cultured under in vitro conditions closer to the relevant in vivo situation. Hence monolayer, suspension, agar, alginate and organ cultures were prepared simultaneously and kept for up to 60 days. Chondrocytes were stimulated by the addition of IFN-gamma and tested for class II antigens. For the detection of the antigens immunocyto- and immunohistochemical APAAP stainings as well as flow cytometric measurements were made. In all examined culture systems a class II antigen induction could be observed. Any significant differences between the various cultures as to the intensity of antigen expression could not be detected. Consequently, the expression of class II antigens on stimulated human chondrocytes seems not to be a specificity of monolayer cultures. Therefore, class II antigen induction may be considered to play a role in the rejection/resorption of vitally grafted cartilage in reconstructive surgery.