Comparative studies of lymph node cell subpopulations and cytokine expression in murine model for testing the potentials of chemicals to induce respiratory sensitization.

OBJECTIVES To investigate immunological changes in lymph nodes based on expression of cell-specific receptors and cytokine expression profile and accompanying inflammatory reactions in lungs of mice treated with chemicals of known potentials to induce respiratory sensitization and those in which activity in this regard is unclear. MATERIALS AND METHODS On day 1 and 7, Balb/c mice received toluene-2,4-diisocyanate (TDI), trimellitic anhydride (TMA), 1-chloro-2,4-dinitrobenzene (DNCB), glutaraldehyde (GA), formaldehyde (FA), benzalkonium chloride (ChB) or vehicle. On day 14, they received a single intranasal instillation with the same chemical or vehicle. On day 15, auricular lymph nodes (LN) were excised and used for analyzes of T-, B-cells, expression of CD44 and for the estimation of IL-4 and IFN-gamma production after in vitro stimulation with concanavalin A (ConA) and also for IL-4 and IFN-gamma mRNA expression analyses using Real-Time PCR. Inflammatory changes in lungs were observed by estimation of TNF-alpha and MIP-2 concentrations and cell numbers and their type in BAL. RESULTS There were no significant changes in cell subpopulations of T helper cells in LN. The percent of B cells was significantly increased after treatment with DNCB, TDI, and GA. Increased expression of CD44 on T cells was also observed. Both IL-4 and IFN-gamma were found increased in TDI- and FA-treated mice, while only IL-4 was increased in TMA-treated mice. Real-Time PCR analyses, however, showed increased IL-4 mRNA expression for TDI- and TMA-, and IFN-gamma mRNA expression for DNCB-treated mice. We haven't observed significant changes in inflammatory reactions in the lungs of exposed animals. CONCLUSIONS Studying immunological changes with first determining the activation status of T cells followed by analyzes of expression of mRNA for Th1 and Th2 cytokines in murine model could be a useful method for assessment of the potentials of chemicals to induce respiratory sensitization but is not sufficient. Addition of ventilatory measurements, but not necessarily inflammatory reactions, could complete the model.