Cockroach allergen exposure and plasma cytokines among children in a tropical environment

Abstract

Background: Little is known about the effects of socioeconomic status or cockroach allergen on immune responses in school-age children, particularly in tropical environments.

Objective: To examine whether cockroach allergen and/or socioeconomic status is associated with plasma cytokine levels in Puerto Rican children.

Methods: This was a cross-sectional study of 532 children (6-14 years old) with (n = 272) and without (n = 260) asthma in San Juan (Puerto Rico). House dust allergens (cockroach [Bla g 2], dust mite [Der p 1], cat dander [Fel d 1], dog dander [Can f 1], and mouse urinary protein [Mus m 1]) were quantified using monoclonal antibody arrays. A panel of 14 cytokines (interleukin [IL]-1β, IL-4, IL-6, IL-10, IL-17A, IL-17F, IL-21, IL-22, IL-23, IL-25, IL-31, IL-33, interferon-γ, and tumor necrosis factor-α) was measured in plasma samples. Low household income was defined as less than $15,000 per year (below the median income for Puerto Rico in 2008-2009). Linear regression was used for the analysis of cockroach allergen and plasma cytokines.

Results: In a multivariable analysis adjusting for low income and other allergen levels, cockroach allergen was significantly associated with decreased IL-17A and with increased levels of 8 cytokines (IL-4, IL-10, IL-17F, IL-21, IL-25, IL-31, interferon-γ, and tumor necrosis factor-α). After stratifying this analysis by cockroach allergy (ie, having a cockroach positive immunoglobulin E reaction), our findings remained largely unchanged for children sensitized to cockroach but became weaker and statistically nonsignificant for non-sensitized children.

Conclusion: Cockroach allergen has broad effects on adaptive immune responses in school-age children in a tropical environment, particularly in those sensitized to cockroach.

Figure 1. Multivariable analysis of cockroach allergen exposure and plasma cytokines in study participants

*Bla g 2 level in house dust (U/g) and plasma cytokine levels (pg/ml) were log-transformed for data analysis. For each cytokine, models were adjusted for age, gender, low household income, case-control status, and house dust levels of: Mus m 1, Fel d 1, and Can f 1. All reported associations were significant at P < 0.00357 (0.05/14 tests).