[In vivo use of OKT3 monoclonal antibodies in recipients of renal allografts].

The OKT3 monoclonal antibody, that is specific for all mature human T lymphocytes represents a potent immunosuppressant when injected in vivo. The OKT3 antibody has been administered to more than 500 renal allograft recipients either to treat or prevent acute rejection episodes. OKT3 exerts its immunosuppressive effect by inducing rapid and important T cell depletion following the first injection. Then, OKT3 mediates the antigenic modulation of its T cell target antigen a phenomenon that is also related to the immunosuppressive effect exerted by the monoclonal antibody. The principal side effect observed following OKT3 administration, particularly if the antibody is injected alone, is the xenosensitisation against the foreign protein. Essentially, two sorts of anti-OKT3 antibodies are produced that respectively recognize the isotypic and the idiotypic determinants of the antibody molecule. The different strategies that may be envisaged to overcome this important side effect, that may totally neutralize the therapeutic effectiveness of OKT3 are discussed in detail.