Inhibitory effect of pregnancy on the migration of the inflammatory cells: a quantitative histological study

The migration of inflammatory cells and fibroblasts into dacron mesh tissue (Mersilene), immersed in saline or in a solution containing live BCG and implanted under the skin of virgin and pregnant female guinea-pigs, was investigated. Cell counts have shown that in pregnant females significant reduction (about 50%) of migration of the inflammatory cells occurred in both saline and live-BCG-immersed implants. The effect was maximal (-81%) on macrophage level in implants immersed in saline, whereas the action was prominent on neutrophils level (-66%) in implants containing live BCG. In the case of implants devoid of live BCG, the inhibitory effect of pregnancy on migration of the inflammatory cells and fibroblasts seemed not to be directly related to any immunological process. This experiment suggests that inhibition could be mediated via an undefined factor interacting with cell membranes to diminish their functional activities.