It is known that exposure to As+3 via drinking water causes a disruption of the immune system and significantly compromises the immune response to infection. The purpose of these studies was to assess the effects of As+3 on bone marrow progenitor cell colony formation and the humoral immune response to a T-dependent antigen response (TDAR) in vivo. In a 30 day drinking water study, mice were exposed to 19, 75, or 300 ppb As+3. There was a decrease in bone marrow cell recovery, but not spleen cell recovery at 300 ppb As+3. In the bone marrow, As+3 altered neither the expression of CD34+ and CD38+ cells, markers of early hematopoietic stem cells, nor CD45-/CD105+, markers of mesenchymal stem cells. Spleen cell surface marker CD45 expression on B cells (CD19+), T cells (CD3+), T helper cells (CD4 +) and cytotoxic T cells (CD8+), natural killer (NK+), and macrophages (Mac 1+) were not altered by the 30 day in vivo As+3 exposure. Functional assays of CFU-B colony formation showed significant selective suppression (p<0.05) by 300 ppb As+3 exposure, whereas CFU-GM formation was not altered. The TDAR of the spleen cells was significantly suppressed at 75 and 300 ppb As+3. In vitro studies of the bone marrow revealed a selective suppression of CFU-B by 50 nM As+3 in the absence of apparent cytotoxicity. Monomethylarsonous acid (MMA+3) demonstrated a dose-dependent and selective suppression of CFU-B beginning at 5 nM (p<0.05). MMA+3 suppressed CFU-GM formation at 500 nM, a concentration that proved to be nonspecifically cytotoxic. As+5 did not suppress CFU-B and/or CFU-GM in vitro at concentrations up to 500 nM. Collectively, these results demonstrate that As+3 and likely its metabolite (MMA+3) target lymphoid progenitor cells in mouse bone marrow and mature B and T cell activity in the spleen.
ASJC Scopus subject areas
- Agricultural and Biological Sciences(all)
- Biochemistry, Genetics and Molecular Biology(all)