Relationship between IgE positive cell numbers and serum total IgE levels in mice treated with trimellitic anhydride and dinitrochlorobenzene.

Although increased total serum IgE levels have been suggested as being predictive parameters of airway hypersensitivity caused by low molecular weight chemicals, it is not yet clear what level of serum total IgE in chemically-treated animals would translate to potential risk of inducing an immediate type hypersensitivity in human beings. Quantitative determination of IgE-bearing positive cells induced by chemicals in the tissue, particularly in respiratory airway, could help to resolve this problem. In BALB/c mice, serum total IgE concentrations and tissue IgE-bearing positive cell numbers were investigated following topical exposure to the chemicals, trimellitic anhydride (TMA) and dinitrochlorobenzene (DNCB), known in human as a respiratory and dermal sensitizer, respectively. In groups of mice 8 and 10 weeks of age, there were less individual variations in 25% TMA-induced serum total IgE increase than in other groups of mice 6, 12 and 16 weeks of age. When chemical concentrations of 1, 2 and 3% DNCB and of 6.25, 12.5 and 25% TMA were studied, we observed that the increase in IgE was dose-dependent for both chemicals, r=0.96; P=0.03 for DNCB and r=0.99; P=0.002 for TMA. However, the increase in serum total IgE induced by TMA was at least twice that induced by DNCB and was associated with the numbers of IgE bearing cells in the tracheal lamina propria (r=0.67, P=0.0003). A respiratory hypersensitivity caused by TMA, but not by DNCB, may be partly due to the presence of immuno effector cells bearing IgE at their surface in airway microenvironments, and their presence might be related to the higher level of serum total IgE. The IgE bearing positive cells could, therefore, help to identify chemicals which have the potential risk of inducing an immediate type hypersensitivity in humans.