Variations in serum levels of interleukin (IL)-1β, IL-2, IL-6, and tumor necrosis factor-α during specific immunotherapy

Background: Cytokine production by T helper cells is essential for the induction and maintenance of allergic inflammation in the bronchial mucosa. According to recent views, specific immunotherapy (SIT) favors the differentiation of T lymphocytes into cells of the Th1 rather than those of the Th2 subset. Objective: To determine whether or not SIT induces a decrease in the inflammatory reaction by studying eventual variations in the serum levels of IL-1β, IL-2, IL-6, and TNF-α in allergic subjects during SIT. Methods: Serum levels of IL-1β, IL-2, IL-6, and TNF-α were determined before and after 3, 6, and 9 months of SIT by an immunoradiometric assay (IRMA) in 11 adults with perennial allergic asthma and/or rhinitis caused by house dust mites and in 6 nonatopic healthy volunteers. Results: Median serum IL-1β and TNF-α levels of the patients were significantly higher at baseline than those of the controls and decreased during SIT to values similar to or lower (P <.01) after 6 months of SIT for TNF-α than those of the controls. Median serum IL-2, significantly lower at baseline than in the controls, increased during SIT to a level similar to that of the controls. Although the median values of IL-1β and TNF-α in the patients tended to decrease and those of IL-2 to increase during SIT, the differences were not significant; the correlation coefficients (r) of the serum levels of IL-1β, IL-6, and TNF-α versus duration of SIT were negative, while that of IL-2 was positive. Conclusions: Decreases in median serum IL-1β and TNF-α levels during SIT, together with the increases in serum IL-2 and IL-6, compared with those of the controls furnish evidence supporting a reduction in the inflammatory response in the course of SIT.