Integration of the Human Lymphocyte into Immunotoxicological Investigations

Abstract

The xenobiotics acetoxydimethylnitrosamine (ACDMN), acrolein (ACR), and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) are potent immunosuppressive agents of the in vitro primary humoral response of murine splenocytes. The focus of these studies was to determine if human lymphocytes could be modulated by direct exposure to these xenobiotics and therefore be used as an in vitro model system for immunotoxicological in vestigations. In these studies, we compared the profile of activity of these xenobiotics on cultured murine splenocytes (SPLC) and human tonsillar lymphocytes (HTL). With SPLC, we measured the anti-sheep erythrocyte (SRBC) IgM response with the standard direct plaque assay, pokeweed mitogen (PWM)-induced proliferation and the total IgM response to PWM with the reverse plaque assay (RPA). With HTL, we measured PWM induced proliferation and the total Ig(M + A + G) response to PWM with the RPA. ACDMN inhibited the murine SPLC anti SRBC antibody response, PWM-induced proliferation and IgM antibody-forming cell (AFC) responses at concentrations between 0.1 and 10 μM. In HTL, ACDMN inhibited PWM-induced proliferation and the Ig(M + A + G) AFC response over a comparable concentration range. ACR had little activity at concentrations of 10 μM or less. However, ACR at a concentration of 100 μM completely suppressed all the responses of either SPLC or HTL. This concentration was also associated with a marked decrease in cell viability. In contrast, TCDD had a different profile of activity. TCDD inhibited the murine SPLC anti-SRBC IgM response at 3.0 and 30 nM. However, TCDD had no effect on either PWM-induced proliferation or antibody production in either murine SPLC or HTL. TCDD did cause a significant reduction in the background proliferation (i.e., no PWM) of both murine SPLC and HTL at all doses tested. These studies suggest that HTL can provide a comparable profile of activity as murine SPLC and can therefore be utilized for evaluating the direct immunotoxic potential of certain xenobiotics.