Progenitor mast cells and tryptase in Q fever

•Mast cell progenitor counts were decreased in the blood of Q fever patients.•Serum tryptase levels were higher in Q fever patients than in healthy donors.•Numbers of circulating mast cell progenitors correlated with serum tryptase levels in Q fever patients with valvular lesions.•Mast cell progenitors and serum baseline tryptase level are specifically affected Q fever patients.