[Macrophage "disappearance" from the peritoneal cavity as affected by a specific antigen]

Investigations were carried out into the effect of a specific antigen on the changes in the macrophage count in the peritoneal exudate of guinea pigs sensibilized with a live Salmonella abortus ovis culture, with and without an allergic reaction of a delayed type. The setting in of the allergic response was shown to correlate with the decrease in the number of macrophages--in animals with a positive response there was a strong drop of the macrophage count in the peritoneal exudate. It is stated that the changes observed in the number of these cells are directly associated with the dose used: they are more strongly manifested when larger amounts of the S. abortus ovis antigen are used.