Effects of irradiation, anti-thymocyte serum and corticosteroids on PHA and LPS responsive cells of the mouse.

Peripheral lymphocytes responsive to stimulation by phytohaemagglutinin (PHA) and bacterial lipopolysaccharide (LPS) in culture have been quantitated following treatment of mice with anti-thymocyte serum (ATS), total body irradiation or corticosteroids. The ATS reduced the number of PHA-responsive cells in both blood and spleen, and induced splenomegaly, but it had little deleterious effect on spleen-borne LPS-responsive cells. In contrast, the spleens of mice treated with hydrocortisone acetate were atrophied and the remaining cells had a reduced LPS response and an enhanced PHA response. Total body irradiation impaired both PHA and LPS responsiveness in the spleen. Recovery of PHA responsiveness after either irradiation or ATS treatment was prolonged and was dependent on the presence of an intact thymus; recovery of LPS responsiveness after corticosteroid treatment was more rapid and was thymus-independent.