Immune function assays as indicators of chromate exposure.

The potential immunomodulatory effects of chromium were investigated using a series of in vitro and in vivo studies. Chromium (as K2CrO4) in concentrations spanning five orders of magnitude was added in vitro to T-lymphocyte (concanavalin A) and B-lymphocyte (liposaccharide) mitogen cultures and was found to inhibit T-lymphocyte responses at all concentrations tested and to inhibit B-lymphocyte responses at all but the lowest concentration tested (0.01 mg/L). When the same concentrations of chromium were employed in mixed lymphocyte cultures, antigen-induced thymidine uptake was inhibited at the highest concentrations (100 mg/L-1 mg/L), enhanced at 0.1 mg/L, and equal to control values at lower concentrations. Splenocytes isolated from rats exposed to K2CrO4 in drinking water exhibited enhanced responses to T- and B-lymphocyte mitogens. The addition of 0.1 mg/L of chromium to a mixed lymphocyte culture containing splenocytes taken from chromium-exposed rats increased by 5-fold the uptake of thymidine by these cells. These increased responses of cells from chromium-exposed rats may indicate chromium-induced sensitization and may possibly be used as a biological marker for chromium exposure.