The Allergic Rhinitis Clinical Investigator Collaborative (AR-CIC) has previously reported biological outcomes following changes to the protocol for nasal allergen challenge (NAC). Using our cumulative allergen concentration (CAC) protocol we investigated whether or not cytokine profiles were reproducible between two separate NAC visits (3 weeks apart).
10 ragweed allergic participants were enrolled, all with AR symptoms in ragweed season and a supportive skin test response. During screening, 4-fold incremental concentrations of ragweed allergen were administered until each participant achieved the qualifying symptom score (Total Nasal Symptom Score (TNSS) >=8/12 and a 50% Peak Nasal Inspiratory Flow (PNIF) reduction). For the subsequent NAC1 visit, (21d later) participants were challenged with one dose of allergen equivalent to the cumulative amount of allergen received during screening. Nasal secretions were collected at baseline, 1hr, 6hr and 24hr post-NAC and cryopreserved. This procedure was repeated at a second NAC visit 21 days later (NAC2). Cytokine levels were determined using the Luminex®x-MAPTMTechnology.
IL-5 and IL-13 were upregulated at 6hr and 24hr post NAC (Wilcoxon matched-pairs test NAC1: IL-5 p=0.0652 both time points, IL-13 p=0.0273 at 6h; NAC2: IL-5 p=0.0156 at 24hr, IL-13 p=0.0547 at 6hr). IL-6 was upregulated at 1hr, MCP-1 and MIP-1b were upregulated at 24h. Other pro-inflammatory cytokines, chemotaxis and growth factors remained mainly unchanged following NAC. In general, cytokine levels appeared slightly lower for NAC2.
Cytokine profiles appear very similar between both NAC visits using a small set of atopic samples. The 24hr time-point was an important addition to the AR-CIC protocol.