The effects of arsenic compounds on human and bovine lymphocyte mitogenesis in vitro

The response of human and bovine peripheral blood lymphocytes to PHA stimulation was measured in the presence of low concentrations of sodium arsenite and sodium arsenate. In bovine lymphocytes, 41% augmentation of the response occurred at 10(-6) M arsenite with a return to the normal response at 2.5 X 10(-6) M. Complete inhibition of mitogenesis occurred at 6 X 10(-6) M. In the presence of sodium arsenate, similar results were obtained but at the higher concentrations of 2 X 10(-5) (for 57% augmentation), 5.2 X 10(-5), and 1.9 X 10(-4) M, respectively. The possible significance of these findings in view of the known relationship between chronic arsenicalism and human skin cancer is discussed. It is suggested that arsenic compounds may, by potentiating mitogenesis, increase the possibility of errors in DNA replication, some of which could be potentially carcinogenic. Additionally, interference with the immune response could enable potentially cancerous cells to escape immune surveillance.