Cellular and Humoral Responses to Cte f 2, a Cat Flea Allergen, in Children with Papular Urticaria

Abstract

Background: Papular urticaria (PU) is a common insect bite skin hypersensitivity in tropical countries. In order to gain insight into its causal allergens, we aimed to evaluate cellular and humoral immune responses to the recombinant salivary antigen Cte f 2 from the cat flea Ctenocephalides felis. Method: Sixty patients with PU and 27 healthy controls were included in this study. Specific IgE, IgG, IgG1, and IgG4 against Cte f 2 and C. felis extract were determined by ELISA. The T-cell response was analyzed using a carboxyfluorescein succinimidyl ester (CFSE)-based dilution assay and Th1/Th2/Th17 cytokine measurements. In addition, a proteomic analysis of IgG and IgE reactive spots of C. felis extract was performed. Results: The frequency of IgE sensitization to Cte f 2 was similar between patients (36.7%) and controls (40.7%). The specific IgE, IgG1, and IgG4 responses to Cte f 2 and C. felis extract were not significantly different between patients and controls. Among the 3 conditions (i.e., Cte f 2, C. felis extract, and only medium) Cte f 2 was the strongest inducer of CD3+CD4+ proliferation in the patients; however, the mean response was not significantly different from those in controls (Cte f 2: 4.5 vs. 2.5%; p = 0.46). No salivary proteins were identified in C. felis, and most of the spots were identified as muscle-skeletal components (tropomyosin, actin, myosin, and ankirin). Conclusions: Cte f 2 induces IgE and IgG production as well as T-cell proliferation in children living in a geographical area where PU induced by a flea bite is common. The use of C. felis extract is not recommended for the study of bite-induced hypersensitivity disease since salivary antigens are not well represented.

Novel salivary gland allergens from tropical mosquito species and IgE reactivity in allergic patients

“…In addition, they contain nonsalivary gland allergens, such as tropomyosin, that could be cross-reactive to other species such as house dust mite 21 or Cte f 2 that could crossreact with cat flea. 22 Moreover, the commercial test is based on A. communis which is not distributed in tropical areas. 8,9 These A. communis WBE-based commercial tests are insensitive and give positive findings for less than 30% of the patients in the tropics.…”

Allergy to stings and bites from rare or locally important arthropods: worldwide distribution, available diagnostics, and treatment

“…89 Papular urticaria describes a generalized type 4 hypersensitivity characterized by chronic recurrent eruptions due to the bites from fleas and other insects. 90,91 The disease causes significant morbidity, especially in children from tropical countries.…”

“…122 Another cat flea allergen first described from whole-body extracts (Cte f 2) 123,124 has been recently identified as an antigen 5-like protein. 91 Kissing bugs and bed bugs (Heteroptera)…”

Allergy to stings and bites from rare or locally important arthropods: Worldwide distribution, available diagnostics and treatment

“…122 Another cat flea allergen first described from wholebody extracts (Cte f 2) 123,124 has been recently identified as an antigen 5-like protein. 91 4.4.8 | Kissing bugs and bed bugs (Heteroptera)…”