RATIONALE: Airway inflammation is a characteristic feature of asthma. Many inflammatory cells and cytokines contribute to airway inflammation in astma, including Th2 lymphocytes and IL-4, IL-5 and IL-13. Interleukin-7 is secreted by bone marrow stromal cells and it stimulates survival and expansion of immature precursors of B and T lymphocytes. Recently, It has reported that the production of IgE induced by IL-7 in human peripheral blood mononuclear cells was potentiated by the presence of T cells. Lymphocytes proliferation, specifically associated with allergic astma are regulated by several cytokines, so we studied serum IL-7 levels in patients with allergic asthma.The study included 38 patients with allergic asthma (27 female, 11 male; mean age 36.00 ± 4.28 years, disease duration 10.32 ± 4,42 years), 15 patients with allergic rhinitis (13 female, 2 male; mean age 33.2 ± 5.22 years, disease duration 6.74 ± 2.45 years) and 14 healthy controls (11 female, 3 male; mean age 34.72 ± 3.12 years). The levels of serum IL-7 were measured with EIA.The mean IL-7 levels in the sera of patients with allergic asthma was 164.30 ± 35.88 ng/ml, allergic rhinitis was 108.33 ± 14.65 ng/ml and healthy controls was 91 ± 22,18 ng/ml. The levels of serum IL-7 were significantly elevated in patients with allergic asthma compared to allergic rhinitis and healthy controls (P= 0.023 and P=0.018 respectively). Serum IL-7 levels were similar in the patients with allergic rhinitis and healthy controls (P=0.349).As a result; serum IL-7 levels were increased in patients with allergic asthma. RATIONALE: Airway inflammation is a characteristic feature of asthma. Many inflammatory cells and cytokines contribute to airway inflammation in astma, including Th2 lymphocytes and IL-4, IL-5 and IL-13. Interleukin-7 is secreted by bone marrow stromal cells and it stimulates survival and expansion of immature precursors of B and T lymphocytes. Recently, It has reported that the production of IgE induced by IL-7 in human peripheral blood mononuclear cells was potentiated by the presence of T cells. Lymphocytes proliferation, specifically associated with allergic astma are regulated by several cytokines, so we studied serum IL-7 levels in patients with allergic asthma. The study included 38 patients with allergic asthma (27 female, 11 male; mean age 36.00 ± 4.28 years, disease duration 10.32 ± 4,42 years), 15 patients with allergic rhinitis (13 female, 2 male; mean age 33.2 ± 5.22 years, disease duration 6.74 ± 2.45 years) and 14 healthy controls (11 female, 3 male; mean age 34.72 ± 3.12 years). The levels of serum IL-7 were measured with EIA. The mean IL-7 levels in the sera of patients with allergic asthma was 164.30 ± 35.88 ng/ml, allergic rhinitis was 108.33 ± 14.65 ng/ml and healthy controls was 91 ± 22,18 ng/ml. The levels of serum IL-7 were significantly elevated in patients with allergic asthma compared to allergic rhinitis and healthy controls (P= 0.023 and P=0.018 respectively). Serum IL-7 levels were similar in the patients with allergic rhinitis and healthy controls (P=0.349). As a result; serum IL-7 levels were increased in patients with allergic asthma.