Clinical and immunological evaluation of cat-allergic asthmatics living with or without a cat

Abstract

Abstract Rationale We aimed to evaluate the impact of daily cat exposure in cat allergic asthmatics by both clinical symptom and immunological measures. Methods Twenty adults with history of cat-induced asthma and rhinitis, positive serum cat dander-specific IgE (sIgE>0.35kU/L) and Skin Prick Test (SPT) were enrolled at a 1:1 ratio according to cat ownership. For comparison, cat extract- and Fel d1- specific basophil sensitivity test (BST), serum sIgE, sIgG4 and SPT were measured on Day 1 and 28; ambulatory spirometry and symptom measures were obtained daily. Feld1 and 4-reactive CD4+ T cells were profiled using a CD154 upregulation assay. Results Cat owners had higher clinical symptom scores & medication use and a trend toward lower FEV1 vs. those not living with cats. Significantly higher levels of cat dander sIgG4 were observed among cat owners, but no significant difference was observed for cat-dander sIgE or SPT. All subjects tested positive on BST to Fel d1 and cat dander. Cat-ownership was associated with reduced basophil sensitivity to Fel d1, but had positive BST to Fel d4 and 7. T-cell response to Fel d1 and 4 were differentially polarized, with Fel d1 responses strongly polarized toward Th2 in both groups. No significant correlation was observed between basophil and T cell responses against cat allergen components. Conclusions Cat allergic subjects living with a cat demonstrated reduced pulmonary function and greater clinical symptom severity, despite higher medication use and sIgG4. An immunological difference between cat-owners vs. non cat-owners was detected by basophil assay but not by T-cell response.