Analysis of immunotoxicity by enumeration of antibody-producing B cells

Immunotoxicity and allergenic potential induced by topical application of perfluorooctanoic acid (PFOA) in a murine model

Perfluorooctanoic acid (PFOA) is a per- and polyfluoroalkyl substance (PFAS) once used as a surfactant in the polymerization of chemicals. Because of its ubiquitous nature and long half-life, PFOA is commonly detected in the environment, wildlife, and humans. While skin exposure to PFOA is of concern, studies evaluating the immunotoxicity of dermal exposure are lacking. These studies evaluated the immunotoxicity of PFOA (0.5-2% w/v, or 12.5-50 mg/kg/dose) following dermal exposure using a murine model. PFOA (0.5-2%) was not identified to be an irritant or sensitizer using the local lymph node assay. The IgM antibody response to sheep red blood cell. was significantly reduced in the spleen following 4-days of dermal exposure (2%). PFOA exposure produced a significant decrease in thymus (1 and 2%) and spleen (0.5-2%) weight along with an increase in liver weight (0.5-2%). Immune cell phenotyping identified a reduction in the frequency (1 and 2%) and number (0.5-2%) of splenic B-cells. To further define the mechanism of immunotoxicity, gene expression was also evaluated in the skin. The findings support a potential involvement of the nuclear receptor PPARα. These results demonstrate that dermal exposure to PFOA is immunotoxic and raise concern about potential adverse effects from dermal exposure.

Developmental immunotoxicity is not associated with the consumption of transgenic Bt rice TT51 in rats

TT51 is a transgenic strain of Bt rice generated by fusing a synthetic CryAb/Ac gene into MingHui rice. In this study, rats from F0, F1, and F2 generations were fed a diet with 60% TT51 rice, MingHui rice, or nominal-origin rice. The study focused on developmental immunotoxicity in F1 and F2 offspring after long-term consumption of TT51. A wide range of immunological parameters was monitored in this two-generation study on reproductive toxicity. The experiments were performed on F1 and F2 offspring at postnatal days 21 and 42. No adverse clinical effects were observed in any of the experimental groups. In addition, histopathology observations and immunotoxicity tests, including hematological indicators, spleen lymphocyte subsets, natural killer cell activity, lymphoproliferative response, and plaque-forming cell assay, revealed no significant difference between the groups. These results indicated that developmental immunotoxicity was not associated with a diet of transgenic Bt rice TT51, compared to the parental MingHui rice.

Immunotoxicity and allergic potential induced by topical application of dimethyl carbonate (DMC) in a murine model

Dimethyl carbonate (DMC) is an industrial chemical, used as a paint and adhesive solvent, with the potential for significant increases in production. Using select immune function assays, the purpose of these studies was to evaluate the immunotoxicity of DMC following dermal exposure using a murine model. Following a 28-day exposure, DMC produced a significant decrease in thymus weight at concentrations of 75% and greater. No effects on body weight, hematological parameters (erythrocytes, leukocytes, and their differentials), or immune cell phenotyping (B-cells, T-cells, and T-cell sub-sets) were identified. The IgM antibody response to sheep red blood cell (SRBC) was significantly reduced in the spleen but not the serum. DMC was not identified to be an irritant and evaluation of the sensitization potential, conducted using the local lymph node assay (LLNA) at concentrations ranging from 50-100%, did not identify increases in lymphocyte proliferation. These results demonstrate that dermal exposure to DMC induces immune suppression in a murine model and raise concern about potential human exposure and the need for occupational exposure regulations.