New Approach to Studying the Differentiation Processes of Lymphoid Cells under X-Irradiation

Many of the difficulties in the interpretation of in-vivo effects of X-irradiation maybe circumvented by the use of an in-vitro system. At present, however, a completely in-vitro system is not readily available for irradiation studies. To create a culture system which would permit proliferation of cultivated cells and investigation of cellular changes under different conditions, the authors constructed a chamber employing a continuous flow of blood plasma from an extracorporeal circuit in experimental animals. Such a system also made it possible to investigate a specific lymphoid cell population after X-irradiation, avoiding the indirect effects associated with whole-body irradiation of the organism. The culture system employed membrane filters (porosity 0.1- 0.3 μm) which allowed the plasma to pass from the extracorporeal blood circulation into the culture chamber for nourishment. The filters permitted free diffusion of all low and high molecular weight plasma substances, but excluded all cells. The cultured cells and plasma medium were maintained for up to 10 days for experimental analysis. In this system, the lymphoid cells not only survived but proliferated and underwent mitosis, as was established by means of cytological and autoradiographic analysis. Measurements of the degree of X-radiation injury to the proliferative capacity of allogeneic lymphoid cells from the cervical lymph nodes of goats were performed. The response of lymphoid cells to antigenic stimulation (bacteriophage ∅ x 174) was employed as an index of their ability to differentiate after exposure to various doses of X-irradiation. Different degrees of cellular injury in the lymphoid population developed as a function of the radiation exposure dose. For example, with 200 rad antigen stimulation 5 hours later very strongly stimulated blastogenesis. Mitotic activity first appeared 11 hours after exposure. Control lymphoid cultures, stimulated antigenically, showed other differential parameters. Higher doses of X-irradiation produced even greater damage. (author)