Immunological Considerations on the Use of Monoclonal Antibodies for In Vitro and In Vivo Modification of Alloimmunity

Abstract

The modality of treatment offered by the use of monoclonal antibodies has been introduced, in the 1980s, to practical clinical organ transplantation. Thus, the anti-T cell monoclonal antibody OKT3 (Ortho Multicenter Transplant Study Group 1985) is a registered drug for treatment of rejection of allografts in most countries. In addition, there have been several clinical trials conducted with many other monoclonal antibodies directed to T cells, used either as a prophylactic drug to prevent or to treat rejection (Kirkman et al. 1983; Takahashi et al. 1983; d’Apice et al. 1987; Friend et al. 1989; Kurrle et al. 1989; Waid et al. 1989; Wee et al. 1989). The efficacy of treatment and the immediate clinical side effects have concerned the transplantation community. However, very little attention has been paid to other possible shortand long-term consequences. Thus, injection of monoclonal antibodies directed to a physiological ligand or receptor might interfere with its normal function and cause various forms of permanent immunosuppression. Alternatively, the infused antibodies might interact with molecules other than the one the antibody is designed for. Up to date, the frequency and possible consequences of such undesired effects of treatment are unknown. Results obtained in experimental animal models may constitute a basis for discussion about the pros and cons of monoclonal antibody treatment.