EFFECTS OF MERCURIC-CHLORIDE AND SODIUM SELENITE ON SOME IMMUNE-RESPONSES OF BLUE GOURAMI, TRICHOGASTER-TRICHOPTERUS (PALLUS)

The immunotoxicological effects of mercuric chloride and sodium seleni te on blue gourami were studied. Some immune responses ranging from no n-specific to specific were investigated. These include tissue lysozym e activity, kidney lymphocyte proliferation and plasma agglutinating a ntibody titre against bacteria. After 2 weeks of chronic exposure, 0.0 9 mg/l of Hg2+ alone induced a significant increase of kidney lysozyme activity of 4196.3 +/- 1171.0 U/g, but it decreased to 1577.4 +/- 902 .4 U/g when exposed simultaneously to equiconcentration of selenium. P lasma lysozyme activity was also increased by co-administration of Hg2 + and SeO32-. The level of plasma agglutinating antibody against Aerom onas hydrophila L37 was lowered in the chemical-treated fish. This ind icates that the fish immunity was impaired by action of mercury and se lenium. However, the in vitro lymphocyte proliferation test shows that mercury concentration lower than 0.045 mg/l Hg2+ enhanced the mitotic rate of kidney lymphocytes by approximately 30%. A high concentration of mercury caused irreversible damaging effects on con A-induced lymp hoblastogenesis. In contrast, the inhibitory effect of low concentrati ons of mercury could be removed by washing. On the other hand, seleniu m showed a suppressive effect on the lymphocyte proliferation even at 0.5 mg/l. (C) 1998 Elsevier Science B.V.