Exposure of Ancistrus multispinis (Regan, 1912, Pisces, Teleostei) to deltamethrin: Effects on cellular immunity

The objective of this study performed in Ancistrus multispinis was to evaluate whether sublethal doses of deltamethrin (DM) could affect lipopolysaccharide (LPS)-induced leukocyte migration to the peritoneal cavity and the production of nitric oxide (NO) by kidney macrophages exposed to LPS and/or DM. For cell migration studies, 10 fish were exposed to DM 0.1 or 0.3 mg kg^-1 or vehicle for 96 h. After this period, each group received LPS (0.1 μg kg^-1) or saline and the cells were collected after 4 h. For the production of NO, kidney macrophages were isolated from eight fish and the cells were incubated for 24 or 48 h with LPS (10 μg mL^-1) and DM (0.3 and 1 μg mL^-1). The results were analyzed using ANOVA followed by Bonferroni multiple comparisons test. A small leukocyte population (530 ± 30.8 cells μL^-1) was naturally observed in the peritoneal cavity, however after inoculation of LPS, the number of leukocytes was increased by 157%. For the fish treated with DM 0.1 and 0.3 mg kg^-1, total leukocytes had increased by 100 and 162%, respectively. The combination of LPS with the higher dose of DM showed a potentiating or additive effect. The production of NO was increased in all the treated groups in relation to the control group. The group DM 1 μg mL^-1 was also increased in relation to other groups. The "in vitro" method can be used to evaluate the potential effects of toxic agents on the fish immune system. Therefore, we can conclude that DM could increase the NO production of A. multispinis.