Lymphocytes in non-immune inflammation: a specific subclass of lymphoid cells?

Rats were subjected to various experimental procedures which affected lymphocyte numbers, in an attempt to investigate the participation of individual subpopulations of these cells in the development of acute, non-immune inflammation. Deficient T function, as evidenced in neonatally thymectomized animals, or in 6-week-old animals thymectomized and afterwards exposed to multiple total-body X-ray irradiations, did not interfere with the development of the acute inflammatory responses of the animals to carrageenin. In the former circumstance, the numbers of circulating B lymphocytes, identified by the presence of surface immunoglobulins, were increased. In thymectomized and irradiated rats, the B-lymphocyte subpopulation was reduced. Circumstances causing attenuated inflammatory reactions to carrageenin resulted, first, from lymphocyte depletion by chronic drainage from the thoracic duct and, second, from irradiation of the animals with a single large dose of X-ray, the animals being tested 24 h after irradiation. B lymphocytes in blood remained within the normal range after chronic lymphatic drainage, but a large dose of X-ray markedly reduced their number. In both cases the attenuation of the responses to carrageenin did not seem to be associated with nonspecific hyporeactivity, or with the effect of the treatments on the other blood cells, It is suggested that the development of acute, non-immune inflammation is influenced by lymphoid cells which might constitute a specific subclass of cells, distinct from fully differentiated T and B lymphocytes.