Delayed Type Hypersensitivity in Hamsters Infected with Mycoplasma pneumoniae as Revealed by Macrophage Migration Inhibition Test

A delayed type hypersensitivity was demonstrated in hamsters infected with a fresh isolate of Mycoplasma pneumoniae by the following two procedures of macrophage migration inhibition test. In the first procedure, inhibition of migration of peritoneal exudate cells from normal guinea pigs by the addition of splenic cells from infected hamsters in the presence of the mycoplasma antigen was examined. In the second procedure, migration of peritoneal exudate cells, composed of macrophages and lymphocytes, from infected hamsters was examined after the addition of the antigen. Virtually, both procedures gave a similar result, suggesting the presence of cell‐mediated immunity in the infected animals. In these infected hamsters, humoral antibody responses were also demonstrated at the same time.