T Follicular Helper (Tfh) Cells are Activated by Natural Exposure to Pollens During the Ragweed Hay Fever Season
Sunday, March 4, 2018
South Hall A2 (Convention Center)
Jay Jin, MD PhD, Takao Kobayashi, PhD, Kay A. Bachman, RN, Hirohito Kita, MD
RATIONALE: Recent studies in mice suggest that T follicular helper (Tfh) cells play a key role in regulating IgE antibody production to airborne allergens. However, it is unknown whether Tfh cells are involved in allergic immune responses and development of clinical symptoms in humans.

METHODS: Patients with seasonal allergic rhinitis (n=9) to short ragweed (AR) and non-allergic control subjects (NA; n=9) were recruited before the ragweed season in Rochester, MN. Circulating Tfh cells in peripheral blood were characterized by flow cytometry before (pre), during (peak), and after (post) the season. Alternatively, peripheral blood mononuclear cells (PBMCs) were collected, stimulated in vitro with ragweed extract, and analyzed by flow cytometry.

RESULTS: At pre-, peak-, and post-season, no significant differences were observed in total numbers of lymphocytes, CD4+T cells, or Tfh cells (CXCR5+CD4+T cells) within or between groups. In AR, the number of memory-type PD-1+Tfh cells significantly and transiently increased during the peak-season as compared to pre- or post-season (p<0.05). Furthermore, activated Tfh cells (ICOS+PD-1+CXCR5+CD4+T cells) also increased significantly at the peak-season (p<0.05). Such dynamic changes in memory and activated Tfh cells during the peak-season were not observed in NA. When cultured with short ragweed antigen in vitro, the proportion of activated Tfh cells dramatically increased in PBMCs from AR subjects compared to NA subjects (27.5% vs.16.1% at 50 µg/ml extract, median, n=5, p=0.01).

CONCLUSIONS: In patients with allergic rhinitis, activation of Tfh cells occurs by seasonal exposure to ragweed pollen. Tfh cells may be involved in the disease pathophysiology of allergic rhinitis.