The kinetics of mast cells in lymph nodes of immunized mice.

A statistically significant increase in the number of mast cells in popliteal lymph nodes of A-2G mice has been observed after intramuscular injection into one hind leg of sheep red blood corpuscles (SRBC), bovine serum albumin (BSA) and syngeneic kidney cells. The increase was found as early as 5 hours after injection but it was of the same order in ipsilateral and contralateral popliteal lymph nodes. The increase persisted for 24 hours and, in some cases, was followed by a significant decrease below normal values. On the results of [H]-thymidine labelling and of histological observations it seems that cell differentiation and/or migration rather than cell proliferation were responsible for the increase. The effects of stimulation with non-antigenic material suggest that the increase of mast cells is not specifically connected with an immune response.