Influence of Viral Infections on Body Weight, Survival, and Tumor Prevalence of B6C3F1 (C57BL/6N ? C3H/HeN) Mice in Carcinogenicity Studies

Sendai virus (SV), mouse hepatitis virus (MHV), and pneumoniavirus of mice (PVM) are common viral infections of mice. Influenceof these viral infections on the prevalence of liver tumors,lung tumors, and lymphoma is of concern in chemical carcinogenicitystudies. Body weight, survival, and tumor prevalence of B6C3F1mice with and without viral infections in 33 male and 34 femaleuntreated control groups and 32 male and 32 female low- andhigh-dose groups of 2-year chemical carcinogenicity studieswere evaluated. In male mice, the SV infection was associatedwith significantly (p < 0.05) higher survival of control,low-dose, and high-dose groups, and higher prevalence of livertumors and lymphoma. The increases in tumor prevalence are possiblydue to an increase in the survival of male mice that had SVinfection. However, when interlaboratory variability and time-relatedeffects were taken into account, the number of significant effectswas consistent with the expected false-positive rate inherentto the statistical procedures. The MHV and PVM infections didnot cause consistent changes in body weight, survival, and tumorprevalences in the control and chemical treatment groups ofmale mice. Viral infections did not cause consistent increasesor decreases in body weight, survival, or tumor prevalence inthe control and chemical treatment groups of female B6C3F1 mice.     

Aldicarb Immunotoxicity: Functional Analysis of Cell-Mediated Immunity and Quantitation of Lymphocyte Subpopulations

Aldicarb Immunotoxicity: Functional Analysis of Cell-MediatedImmunity and Quantitation of Lymphocyte Subpopulations. THOMAS,P., RATAJCZAK, H., DEMETRAL, D., HAGEN, K., AND BARON, R. (1990).Fundam. Appl. Toxicol. 15, 221–230. Adult female B6C3F1mice received distilled water only or water containing 1.0,10, or 100 ppb of aldicarb daily for 34 days. The target concentrationof aldicarb present in the 100 ppb dosing solution was analyticallyverified. To further develop an immune profile of this compound,following aldicarb exposure, the ability of splenic naturalkiller cells and specifically sensitized cytotoxic T-lymphocytesto lyse YAC-1 lymphoma and P815 tumor cells, respectively, wasevaluated. To supplement the functional assays, the impact ofaldicarb exposure on the percentages and absolute numbers oftotal T-cells, T-suppressor, T-helper, and B-cells was evaluated.The absence of statistically significant effects on any of theseparameters supports earlier reports that aldicarb does not resultin adverse effects on the immune system of mice.