New immunomodulator lobenzarit disodium (CCA): activation of IgE class-specific suppressor T lymphocytes and regulation of IgE antibody response enhanced by sublethal X-irradiation in SJL/J mice.

The effect of the new immunomodulator lobenzarit disodium (CCA, disodium-2,2'-iminodibenzoate) on IgE antibody response was studied in X-irradiated SJL/J mice. IgE antibody response to dinitrophenyl-keyhole limpet hemocyanin (DNP-KLH) was enhanced by sublethal X-irradiation (400 R), and this enhanced IgE production was suppressed by unprimed normal spleen cell transfer. Oral administration of CCA, every day from 1 day after immunization with DNP-KLH to 1 day before bleeding out, reduced IgE antibody response in sublethally X-irradiated SJL/J mice. The suppressive effect of CCA in the mice was exerted at an early stage of the IgE antibody response. Moreover, CCA showed IgE class-specific suppression and did not suppress IgG class antibody production. CCA-induced reduction of IgE antibody response in SJL/J mice seems to be mediated by suppressor T cells, since depletion of T cells by treatment with antithymocyte serum and complement abolished the CCA-induced reduction and splenic T cells from CCA-treated mice were able to transfer the suppressive effect.