Effects of hydrocortisone on peritoneal free cells in mice

Effects of hydrocortisone on peritoneal free cells in the mouse were examined by quantitative morphologic procedures. Mice of both sexes at 60 to 65 days of age received one, two, or four successive subcutaneous injections of 0.5 mg hydrocortisone every 24 hrs. After one injection, peritoneal free cells showed a rapid decrease in number during the first 3 hrs. They then increased up to about 1.5 times the control value at 24 hrs and returned to the normal level at 48 hrs in both sexes. After two injections, peritoneal cells showed a significant decrease in number in females during the first 2 days. Thereafter they returned to normal in both sexes at 8 to 12 days. The three major types of peritoneal cells, type I, II and III cells, which have been described in previous papers (ABE et al., 1979a, b; HONMA et al., 1980), differed in response to hydrocortisone. Type I cells (small lymphocytes) were markedly reduced in number immediately after hydrocortisone injection and remained depleted even 12 days after injection. Type II cells (medium-sized mononuclear cells) showed the most remarkable response to hydrocortisone. Changes in the total number of peritoneal cells following hydrocortisone injection were ascribed mainly to those of type II cells. Type III cells (macrophages) did not show any significant changes in number after injection.