Deltamethrin has been extensively reported to cause a number of toxic effects including neurotoxicity, mutagenecity, cardiovascular toxicity, teratogenicity and genotoxicity [8, 18]. Deltamethrin-induced alterations of splenic NK cell activity and SRBC-PFC number has been reported in immunized rats [19]. Other pyrethroids (permethrin, cypermethrin and allethrin) have also been reported to alter the mitogenic response of lymphocyte [20]. Desi et al. [21] showed that cypermethrin lowered

the humoral immune response in rabbits and rats. Iskandarov et al. [22] estimated that a single administration of half of LD50 value of deltamethrin substantially MAPK inhibitor inhibited T-rosette formation and blast formation of the lymphocytes in guinea pigs. Lukowicz and Krechnaik [23] observed that deltamethrin suppressed the immune response

in female BALB/c mice, when 6 and 15 mg/kg oral doses were given in soybean oil for 84 and 15 days, respectively. Deltamethrin markedly lowered the weight and cellularity of lymphoid organs. This could very well mean that it may also act directly or indirectly on lymphoid cells, immunoglobulin metabolism, T/B cell-macrophage cooperation and macromolecular biosynthesis. Additionally, DNA/RNA Synthesis inhibitor the number of PFC producing IgM antibodies in animals exposed to deltamethrin was also significantly decreased. The value of quantitative haemolysis of SRBC was observed to be significantly decreased. This indicates that deltamethrin inhibits the humoral immune response in a manner similar to that of cypermethrin which has been shown to cause these changes [21, 24]. Our results show that individual exposure to deltamethrin (-)-p-Bromotetramisole Oxalate or infection challenge with C. albicans caused a significant reduction in PFC response. Additionally,

a combined exposure of both in any order did not cause additional modulations. This immunosuppressive effect of deltamethrin and infection challenge in our study could be attributed to the reduced ability of the cells to release migration inhibition factors which prevent leukocyte and macrophage inhibition suggesting impairment of effector mechanisms during immune response. A dose dynamic relationship exists between nervous system and immune response [25]. The immunosuppressive effects of deltamethrin observed in our study corroborate well with data on neurotoxicity and behavioural toxicity found in the literature. For example, Crofton and Reiter [25] observed that exposure to deltamethrin (6 mg/kg) significantly decreased motor activity and caused an increase in latency and decrease in amplitude of the acoustic startle response in rats. In this study, also a dose close to this one, i.e. 5.6 mg/kg showed immunosuppression, which may be a consequence of toxic chemical stress induced cholinergic stimulation and its effect on immune cell functions.