[The role of thymic microenvironment in T-cell maturation]. / Maturation des lymphocytes T: rôle du microenvironnement thymique

The role played by different components of thymic microenvironment in T-cell-maturation is examined: antibodies to a soluble thymic factor (STF) were thus shown to inhibit T-cell maturation in the chicken while incubation of bursal "null" cells with STF could induce the differentiation of some of them into T cells. In addition to STF, whose properties resemble those of other soluble thymic factors, an insoluble thymic factor (ITF) is described: it is localized mainly in membranes associated with medullary blood vessels, and its injection to mice provokes an influx of marrow stem cells into the thymus.

Obtaining, evaluation and clinical application of antileukemic antilymphocyte globulin (ALLG) in the treatment of chronic lymphatic leukemia.

Antileukemic antilymphocyte globulin (ALLG) was obtained by immunizing horses with peripheral blood lymphocytes from patients suffering from chronic lymphatic leukemia. After absorbing the serum with erythrocytes, globulins were precipitated from the serum with ammonium sulfate. ALLG preparations were sterile, nontoxic and nonpyrogenic and contained no antibodies against basement membranes or antierythrocytic or antiplatelet antibodies. Nine patients with chronic lymphatic leukemia were treated with the globulin. Methods for selecting patients for treatment with ALLG and for controlled therapy were elaborated. Clinical and hematologic observation in the patients were reported. The high therapeutic efficacy of ALLG with high cytotoxic titer was emphasized. Beneficial hematologic and therapeutic effects were obtained in six patients. Attention was drawn to the efficiency of the combined therapy with ALLG, cytostatics and adrenal steroids.

Inhibition of T-cell differentiation by an antibody to a soluble thymic factor.

An antiserum to chicken soluble thymic factor (STF) was prepared in rabbits and absorbed with chicken thymocytes until it reacted only with thymic reticuloepithelial cells. When injected into 6-day-old embryonated eggs, this antiserum caused a severe depletion of small lymphocytes in the cortical region of the thymus which was filled with large undifferentiated cells. In addition, reticuloepithelial cells displayed a marked disruption of cytoplasmic elements. The percentage of thymic lymphocytes bearing the T antigen was greatly reduced. It is believed that a factor responsible for differentiation of stem cells into T cells has been inhibited.