The Effect of High Levels of Certain Steroids on Induced Lymphocytic Leukemia in the Rat

If one accepts the established fact that the adrenal steroids have regulatory powers over nor mal lymphoid tissue, it would seem reasonable to assume that the adrenal steroids may also regulate the immature cells of lymphocytic leukemia. Since the advent of the clinical use of cortisone and of ÕCTH in April, 1949, many studies on both animals and human beings have been attempted to determine whether cortisone or the adrenocorticotropic hormone had any effect on the lymphoid cells of neoplastic origin. The results reported in the literature are widely diversified. In some cases of acute leukemia definite improvement, from a hématologiestandpoint, was reported. Marrows have been said to revert to a normal picture, and the peripheral blood smears revealed no suggestion of cellular immaturity. These cases, however, have been exceptions. Not only have the great majority of acute leukemias failed to respond, but, at times, the course of the disease has actually ap peared to be accelerated by treatment with either cortisone or adrenocorticotropic hormone. Those few remissions that have been reported to occur were never permanent, and, sooner or later, the blood picture changed from the normal back to the characteristic malignant pattern of acute leuke mia. Subsequent courses of therapy usually failed to produce any further remissions. As yet, there has been no satisfactory explana tion of the action of the adrenal cortical hormones on the blood elements. However, numerous in vestigators have concluded that lymphoid tissue, both fixed and circulating, is probably an end organ over which certain steroid hormones of the adrenal cortex have the power of regulation. Evi dence for this concept can be found in the earlier medical literature. For example, as early as 1895, Star (10) reported the case of a young girl who had died in an Addisonian crisis; at necropsy, marked enlargement of the thymus and other lymphoid tissues was observed. It was 2 years later that