The effect of UFA on Ig production by rat MLN lymphocytes was examined to clarify their influence on allergic reactions. A 4-h treatment at 1 mM inhibited the production of IgA, IgG, and IgM by the lymphocytes, but stimulated IgE production. The IgE production-stimulating activity became stronger with increasing number of carbon atoms and/or double bonds. However, no saturated fatty acid with carbon numbers from 12 to 18 affected IgE production by the lymphocytes. Hydrogen peroxide exerted Ig production-regulating activity similar to that of UFA, suggesting that the effect of UFA is at least partly due to oxidation products. Thus, the effect of antioxidants on the Ig production-regulating activity of arachidonic acid was examined. alpha-Tocopherol and BHT annulled the stimulation of IgE production by arachidonic acid, but ascorbic acid was not effective. The IgE production-enhancing activity of UFA was closely related to their oxidation rate in culture medium. These results suggest that UFA enhance the allergic reaction through the stimulation of IgE production and the inhibition of IgA production, and that hydrophobic antioxidants are partially effective to annul the adverse effect of UFA.

No abstract

The interaction of IL-4, IL-5, and free bile acids with the immunoglobulin production by mouse spleen lymphocytes was studied to examine their immunoregulatory activity. In the absence of lipopolysaccharide (LPS), IL-4 enhanced the IgE and IgG production significantly and the IgA production weakly, but not the IgM production. On the other hand, IL-5 had an inhibitory tendency on the IgE and IgA production, though not significantly. In the presence of LPS, both IL-4 and IL-5 significantly enhanced the IgE production by mouse splenic lymphocytes. When the lymphocytes were cultured with the physiological concentration of free bile acids (10 microM) and LPS for 3 days, chenodeoxycholic acid inhibited the IgE production, but cholic and deoxycholic acids did not. In the presence of IL-4 or IL-5, these bile acids cancelled the stimulatory effects of interleukins and rather significantly inhibited the IgE production. These results suggest that these free bile acids act as an anti-allergic agent.