EFFECT OF PENTACHLOROPHENOL ON IMMUNE FUNCTION

The organochlorine compound, pentachlorophenol, was evaluated for effe cts on immune system function in male Fisher 344 rats. Pentachlorophen ol was prepared in an olive oil vehicle and was administered by oral g avage twice weekly for 28 days at a dose of 2.0 mg/kg per treatment. E xposure to pentachlorophenol increased body weight gains (P = 0.024) d uring the treatment period. Liver (P = 0.034) and kidney (P = 0.012) b ody weight ratios were also increased. Pentachlorophenol exposure enha nced T-lymphocyte blastogenesis induced by concanavalin A (Con A)(P = 0.0001) and phytohemagglutinin (PHA)(P = 0.048) evaluated using stimul ation indices. Corresponding B-lymphocyte blastogenesis induced by lip oploysaccharide/dextran (LPS/dex)(P = 0.0034) was also enhanced by pen tachlorophenol exposure. Pentachlorophenol suppressed the antibody res ponse against sheep red blood cells (SRBCs) by 39% when the response w as expressed per viable spleen cell (P = 0.006). This suppression was not evident when the response was expressed per spleen (P = 0.22), sug gesting that a compensatory mechanism or extramedullary splenic hemopo iesis was occurring minimizing the overall impact on humoral immunity. The enhanced B- and T-lymphocyte blastogenesis may also reflect compe nsatory or hemopoietic activity. Pentachlorophenol exposure had no eff ect on peritoneal macrophage phagocytosis (P = 0.31) or lymphocyte cel l surface antigen expression. The observed alterations in lymphocyte b lastogenesis and humoral immunity subsequent to pentachlorophenol expo sure do not appear to be associated with phagocytosis or lymphocyte ce ll surface antigen expression. (C) 1998 Elsevier Science Ireland Ltd. All rights reserved.