CHANGES OF THE PERIPHERAL LYMPHOCYTE POPULATION FOLLOWING RADIATION-THERAPY TO EXTENDED AND LIMITED FIELDS

The peripheral lymphoid cell populations were examined in 2 groups of breast cancer patients. One group had been treated by wedge excision of the tumor and received postoperatively 5000 rad in 5 weeks through tangential fields encompassing the breast only (limited field treatment). The other group consisted of patients who had been treated by modified radical mastectomy; postoperatively, they received 4500 rad in 5 weeks to the internal mammary, supraclavicular and axillary lymph node regions and the chest wall (extended field treatment). Patients receiving extended field treatment developed the most pronounced lymphopenia. In both groups of patients 2 subpopulations of non-T-lymphocytes, cells possessing receptors for C′3 and cells binding mouse erythrocytes, were depleted to a higher extent than T-cells. The first mentioned populations, however, repopulated faster than the latter. The response of the cells in the mixed lymphocyte culture (MLC) was reduced to the same extent in both groups and correlative studies could not establish any relation between the extent of radiation induced lymphopenia and reduction of MLC responsiveness. Relative phytohemagglutin (PJA) responses, however, were reduced to a higher extent in patients receiving extended field treatment. The results support the concept that radiation induced impairment of antigen reactivity cannot entirely be explained by decreased lymphocyte counts but also by the triggering of immunosuppressive mechanisms such as activation of inhibitor cells. © 1979.