Production of interleukin-12 by monocytes and interferon-γ by natural killer cells in allergic patients during rush immunotherapy

Background: Allergen specific immunotherapy modifies the immunologic response to allergen exposure; however, the role of cells composing the innate immune system, such as monocytes and natural killer (NK) cells, in this mechanism is still unclear. Objective: To examine the effect of rush immunotherapy (RIT) on early allergen-induced cytokine production by peripheral blood mononuclear cells from treated cat- and birch-allergic patients. Methods: Twelve allergic patients received RIT, and another 4 served as controls. Blood samples were taken before the start and after 3 days, 1 week, 3 weeks, and 3 months of RIT. Allergen-induced production of interleukin-12 (IL-12) by monocytes and interferon-gamma (IFN-gamma) by NK cells was evaluated by means of flow cytometry. Results: Before the start of RIT, allergic patients had significantly lower numbers of IL-12(+) monocytes compared with healthy subjects (P = .01). The percentage of IL-12(+) monocytes increased after 3 months of RIT (P = .003). In the allergic control group, the proportion of IL-12(+) monocytes evaluated after 3 months was not different from baseline and was significantly lower compared with that in the RIT group (P = .005). Before treatment, the percentage of IFN-gamma(+) NK cells was lower in allergic patients than in healthy subjects (P = .04). The percentage of IFN-gamma(+) NK cells increased after 3 weeks (P = .03) and 3 months (P = .01) of RIT. Conclusions: Restoration of the cytokine imbalance by immunotherapy is not only restricted to the cells of the adaptive immune system but also concerns cells composing the innate immune system.