Lymphoid cell adenylate cyclase activity after x-irradiation and cortisone treatment.

Cortisone injection and x-irradiation of normal mice lead to extensive destruction of thymus and spleen lymphocytes. The lymphocytes resistant to these treatments have basal adenylate cyclase activities that are the same as or slightly lower than the cells of untreated animals. On the other hand, the ability of the cyclase of the cortisone-resistant and radioresistant lymphocytes to respond to stimulation by epinephrine is greatly diminished. The results provide an explanation for the previously observed lack of epinephrine sensitivity of the cyclase of lymphoid cells of immunodeficient pituitary dwarf mice and suggest that the depressed lymphoid cell population of the dwarf is the result of an inability to recover from stress-related lymphoid involution. It is also suggested that the more mature population of lymphoid cells of normal mice is less responsive to hormonal influences.