Comparison of humoral and cell mediated immune response modulation by chemical and bio‐pesticides

Abstract

The awareness about the negative impact of chemical pesticides on health and, also their indispensability for the agriculture sector, has raised the need for new safer pesticides, in the form of biopesticides. In our previous studies [l-3], it was found that chemical pesticides generally suppress the immune response, but there is hardly any study in which the impact of biopesticides on the immune response has been examined. In the present study a comparison of humoral and cell mediated immune response modulation by three chemical pesticides, i.e. malathione(M), methyl parathione (MP) and dimethoate (DM) and a plantbased commercial biopesticide, Neemazal (NAF), purchased from EID Parry India Ltd Madras) was carried out in vivo in swiss albino mice. The animals, divided into four groups, each consisting of 10 mice, were given either a sublethal dose of one of the pesticides (test) or distilled water only (control) in 10 inoculations, intraperitoneally, over a period of 25-30 days. Animals were immunized with SRBC during the course of inoculations with the pesticide. The blood samples were collected on, the 4"', 7* and ll"* day post-SRBC inculation to check the development of an anti-SRBC antibody and a p mercaptoethanol resistant anti-SRBC antibody (IgG); they were then sacrificed on day 11 post-SRBC inoculation to assess the percent leukocyte migration inhibition (LMI), percent leukocyte adherence inhibition and percent nitroblue tetrazolium chloride reduction by the splenocytes by using the methodology given in the Manual by Bhatia [4]. RESULTSTables I and II showed that in chemical pesticides, i.e. M or MP or DM treated animals the anti-SRBC antibody titres were lower, whereas in the NAF-treated animals the titres were higher than in control animals. Similarly, the percentages of LMI, LAI and NBT were lower •Corresponding author.