The Effects of Tributyltin (TBT) and 3,3′,4,4′,5-Pentachlorobiphenyl (PCB-126) Mixtures on Antibody Responses and Phagocyte Oxidative Burst Activity in Channel Catfish, Ictalurus punctatus

Abstract

The organotin tributyltin (TBT) is an antifouling biocide used in marine paints and is a common pollutant in harbor estuaries. We previously demonstrated that the immune system of channel catfish, Ictalurus punctatus, is a sensitive target organ of TBT. Exposure strongly suppresses humoral immune responses. Harbor estuaries often contain polychlorinated biphenyls (PCBs) due to their ubuquitous distribution. The coplanar congener 3,3',4,4'5'-polychlorinated biphenyl (PCB-126) is also immunotoxic to channel catfish, but it suppresses only the innate immune responses and only at high doses. In this study we exposed channel catfish to TBT, PCB-126, or both in mixtures, with canola oil (CO) serving as the carrier control. Antibody responses to Vibrio anguillarum and phagocyte oxidative burst activity were measured after (1) a single dose of 0.01 or 1 mg/kg of each or both in combination, and (2) six injections of 1.7 or 170 microg/kg of each (or in combination) given every 3 days over a 16-day period to yield a cumulative dose of 0.01 or 1 mg/kg, respectively. We measured antibody responses to V. anguillarum 21 days after immunization and oxidative burst activities 14 and 21 days after the final treatment. The highest dose of TBT suppressed antibody responses after a single exposure. The high dose of PCB-126 also suppressed antibody responses. The addition of PCB-126 to TBT doses did not alter the antibody responses beyond the effects of TBT alone. In the repeated exposure group, only the high dose of TBT suppressed antibody responses. In animals exposed to mixtures, high levels of PCB-126 enhanced suppression associated with low levels of TBT, whereas PCB-126 protected against suppression associated with high levels of TBT. Single exposures to TBT or PCB-126 suppressed phagocyte oxidative burst activity. In animals exposed to mixtures, as a single exposure, the addition of a low dose PCB-126 protected against low dose TBT-related oxidative burst activity suppression. In the repeated exposure groups TBT suppressed oxidative burst activity, but only at the highest dose on day 21, while high doses of PCB-126 suppressed activity on day 14. Furthermore, low levels of PCB-126 reversed the suppressed oxidative burst activity associated with high levels of TBT on day 21. Overall, this study demonstrates moderate additivity in terms of the immunotoxicity of TBT and PCB-126 mixtures using these two endpoints of immune function in the channel catfish model.

Benzo[a]pyrene modulation of acute immunologic responses in red Sea bream pretreated with lipopolysaccharide

“…In this study, the induction pattern of respiratory burst activity was changed when the fish was first exposed to BaP for 14 days and then challenged with LPS and its significant activity was extended until 96 h, which is much longer than that caused by either LPS challenge or exposure to BaP alone. The similar enhanced respiratory burst activity is also found in other study when fish are exposed to pollutants (Regala et al, ; Reynaud et al, ), and the increased production of superoxide anion is considered to be cytotoxic to the host (Cheng et al, ). Therefore, a high level of superoxide anion maintained in the fish as observed in our study may not be benefit but cause damages to the host animals, even though the respiratory burst activity could help the host eliminate the invading foreigners.…”

Polychlorinated biphenyl 126 affects expression of genes involved in stress‐immune interaction in primary cultures of rainbow trout anterior kidney cells

“…The sharp increase of IL‐1β expression levels seen in the present study, after only 30 min of PCB126 incubation, followed by an equally sharp decline after 2 h of incubation, indicates a strong but short‐lived immunotoxic effect of PCB126 when used at doses of 1 and 0.01 μM. In a different study, an inhibition of the innate immune system in channel catfish ( Ictalurus punctatus ) after exposure to PCB was observed [23]. However, in this study [23] the fish were injected and sampled 14 and 21 d after injection; hence, a stimulation of the innate immune system at an earlier time point might have been missed.…”

“…In a different study, an inhibition of the innate immune system in channel catfish ( Ictalurus punctatus ) after exposure to PCB was observed [23]. However, in this study [23] the fish were injected and sampled 14 and 21 d after injection; hence, a stimulation of the innate immune system at an earlier time point might have been missed.…”

Tissue Distribution and Immunomodulation in Channel Catfish (Ictalurus punctatus) Following Dietary Exposure to Polychlorinated Biphenyl Aroclors and Food Deprivation

“…While the effect of food deprivation was generally greater than that for PCB exposure, PCB exposure did decrease bactericidal and oxidative burst activity. This result is consistent with those of previous studies in ictalurids [19,38,54], and suggests that PCB exposure may increase disease susceptibility, which could influence population demography. Notably, bactericidal activity returned to normal seven weeks after the start of a PCB-free diet, suggesting that the effect of PCBs on some immunological responses may be temporary.…”