Influence of 90Sr, adult thymectomy and antilymphocyte globulin on T-cells in mouse peripheral blood.

Three groups of male CBA mice were treated by (1) 90Sr injection (14.8 kBq/g body weight i.p.), (2) adult thymectomy (ATx) + antilymphocyte globulin (ALG), and (3) 90Sr + ATx + ALG, respectively, and one untreated group served as a control. The relative number of T-lymphocytes was determined in peripheral blood mononuclear cells of individual animals using a dye exclusion cytotoxicity assay with antisera against the T-cell surface membrane marker Thy 1.2 and complement. Total and differential leucocyte counts were also performed. 90Sr irradiation decreased the total number of leucocytes irrespective of type, and the combined treatment of ATx and ALG decreased mainly mononuclear cells and particularly T-cells. The most advanced T-cell depletion in peripheral blood was found in the 90Sr + ATx + ALG treated group with a 97 per cent reduction as compared with untreated controls. ATx + ALG thus proved to be useful for blood T-cell depletion in mice treated simultaneously with 90Sr, and might provide a valuable tool in investigations on the possible role of cell-mediated immune response in radiation-induced oncogenesis, with particular emphasis on selective depletion within the monomorphonuclear compartment.