Histamine-binding suppressor T cells in rabbit peripheral blood.

Peripheral blood leukocytes (PBL) from primed rabbits were able to suppress the in vitro anti-sheep red blood cell (SRBC) plaque-forming cell (PFC) response of autologous spleen cells. A population containing the suppressor cells could be isolated from PBL by cell fractionation on columns of insolubilized histamine. In contrast to spleen cells, PBL generatd a weak secondary anti-SRBC response in vitro. A strong response was obtained with PBL freed from histamine-binding (H+) cells. The addition of these H+ cells to cultures of H-PBL caused strong suppression. The H+ suppressor cell was further characterized as a radioresistant T cell. Low-dose irradiation of H- cells resulted in a supplementary enhanced PFC response suggesting that PBL also contain a radiosensitive regulator cell which is not histamine binding.