What is known about blocking factors in renal allograft recipients

A variety of substances present in serum or plasma, either at the time of renal transplant or during stable graft function in long-term recipients, may interfere with cell-mediated immune functions. In several cases the presence of serum blocking factors has been correlated with decreased graft vulnerability to acute rejection. The question is: are serum blocking factors important for the induction or maintenance of allograft tolerance or, alternatively, are they merely by-products of the tolerant state? Perhaps the most compelling case for an essential role of serum blocking factors can be made in instances where vigorous cell-mediated immune responses can be demonstrated in vitro, but anergy (for example, absence of DTH response) is seen in vivo. However, in renal transplant recipients the majority of studies that show the presence of receptor blocking antibodies or other immunoregulatory serum factors also found a decreased cell-mediated immune response in vitro. Thus, allograft tolerance would appear to involve multiple mechanisms as suggested elsewhere. Due to the recent discovery of the molecular structure of the T cell receptor 33,34, it is now possible to identify determinants associated with the binding of T cell receptor blocking antibodies in renal transplant recipients; for example, one should be able to determine if families of V beta genes are involved. Alternatively, it may be possible to identify polymorphic structures on T cells other than the alpha, beta receptor complex as ligands for blocking antibodies.(ABSTRACT TRUNCATED AT 250 WORDS)