IL10 and asthma: There is a large body of epidemiologic data suggesting that vitamin D insufficiency, as defined by the serum 25-hydroxyvitamin D (25[OH]D) concentration, is strongly associated with impaired respiratory health,20 risk of asthma,21,22 asthma severity, and refractoriness to current therapy.23-27 We have previously shown that patients with SR asthma have a defective T-cell IL-10 response to dexamethasone in vitro28 and that this could be restored by 1,25(OH)2D3.29