DISTINCT MODULATION BY INTERFERON-GAMMA (IFN-GAMMA) OF CD23 EXPRESSION ON B-LYMPHOCYTES AND T-LYMPHOCYTES OF ATOPIC SUBJECTS

The low-affinity IEE receptor (Fc epsilon RII/CD23) plays a role in Ig E production. Cytokines participating in IgE synthesis also modulate C D23 expression on lymphocytes, but whether this modulation is differen t in atopic subjects remains unclear. We studied CD23 expression on B and T lymphocytes in 10 asthmatic patients with Dermatophagoides ptero nyssinus hypersensitivity and 10 healthy non-atopic subjects. Studies were performed by flow cytometry, in phytohaemagglutinin (PHA) or IL-4 -stimulated mononuclear cell cultures, alone or in the presence of IFN -gamma. Soluble CD23 (sCD23) released in the culture supernatants was measured by enzyme-linked immunoassay. Both PHA and IL-4 induced the e xpression of CD23 on lymphocytes of atopic and non-atopic subjects. Wh ereas PHA increased both the percentage and mean fluorescence intensit y of CD23(+) B and T cells, IL-4 alone did not increase the percentage of CD23(+) T cells. The effects of IFN-gamma were different in both g roups, since it was able to reduce the percentage of PHA-stimulated CD 23(+) T cells only in non-atopic individuals. In non-atopic subjects m ore than atopic, levels of sCD23 were increased in the supernatants of PHA and IL-4 cultures. These results show that the modulation of CD23 expression is different on B and T cells, and that IFN-gamma acts dif ferently in atopic and non-atopic individuals.