Thymus transplants: a look to the future.

In a review of thymus transplants performed in a variety of immunodeficiency syndromes, results in the DiGeorge syndrome seen uniformly successful. Rapid restoration of lymphocyte responsibility in vitro and achievement of normal peripheral blood lymphocyte counts are characteristic. In nearly all other types of isolated thymic deficiency or combined immunodeficiency there has been only transient or meager restitution and more often than not complete failure. A few exceptions were noted in a combined immunodeficiency state and in two cases of isolated T-cell deficiency. The use of transfer factor may have played an important adjunctive role. Future attempts must depend upon more precise characterization of the defects, utilizing attempts to define subpopulations of T and B cells; consideration of HL-A restrictions; methods of implantation and use of adjunctive measures (eg thymosin) or other cell populations (such as liver or spleen).