Modulation of beta-galactosidase activity in peritoneal macrophages from C57B1 mice after exposure to Proprionibacterium acnes.

Peritoneal macrophages (PM luminal diameter) from untreated C57B1 mice contain high levels of beta-galactosidase (beta-gal) and these PM luminal diameter are heterogeneous in their expression of this enzyme. Intraperitoneal (i.p.) injection of saline caused a transient depression in the level of enzyme activity in the PM luminal diameter whereas i.p. injection of Proprionibacterium acnes (P. acnes) gave rise to a marked decrease of beta-gal activity in these cells. This reduction in enzymatic activity persisted for as long as the PM luminal diameter were activated for cytotoxicity towards the L929 tumor cell line, up to 35 days after injection. beta-gal activity was present in the lavage fluid from day 2-21 after injection of P. acnes but none was detected in the lavage fluid after injection of saline. It is proposed that the enzymatic activity in the lavage fluid is derived from monocytes which migrate from the blood into the peritoneal cavity. There was an influx of granulocytes in the P. acnes group which persisted up to 35 days after injection. In contrast none were observed in the saline group after 2 days. PM luminal diameter harvested after 1-35 days were large, highly vacuolized and many contained bacteria; these PM luminal diameter had the typical morphology of activated cells. It is suggested that the processing of P. acnes by granulocytes may play a role in the activation of macrophages in the early inflammatory response, with concurrent loss in beta-gal activity. However, in the later stages, interferon-gamma and other induced lymphokines may be instrumental in causing a decrease in beta-gal activity.