Effects of Sublethal Irradiation on the Plaque-Forming Cell Response in Mice

Abstract

Abstract X-ray (440 R) administered 4 days after a primary injection of 1 × 108 sheep red blood cells (SRBC) into normal BALB/c mice resulted in increased numbers of indirect plaque-forming cells per million spleen cells (PFC/106) 3 days after a secondary challenge of 1 × 108 SRBC. The results were compared to control, non-x-rayed mice. The time of x-ray in relation to SRBC injection was critical as x-ray 3, 5, or 6 days after primary SRBC injection did not increase the number of PFC/106 cells. The state of increased responsiveness induced by x-ray was dependent on the dose of SRBC used for primary injection and could not be transferred by spleen cells to syngeneic recipient mice. The number of primary direct PFC/106 cells was increased when the response was measured 8 days after injection of SRBC and mice x-rayed 48 hr after antigen injection when compared to control non-x-rayed mice; this increase was probably due to a delay in the response induced by x-ray.