Of the five studies reporting no significant biomarker association with chronic asthma, one reported a positive association of Cp IgM and acute exacerbations (P = 0.03) [16], and another found a positive association of Cp IgA and asthma in the subgroup with inhalant allergy (P = 0.002) but not in the subgroup with food allergy [18]. Here, CD40LG is linked to food allergy.