ABSTRACT
BACKGROUND : Characterization of allergic responses to cockroach
(CR), a common aeroallergen associated with asthma, has focused mainly
on IgE reactivity, but little is known about T cell responses,
particularly in children. We conducted a functional evaluation of CR
allergen-specific T cell reactivity in a cohort of CR allergic children
with asthma.
METHODS : Peripheral blood mononuclear cells (PBMCs) were obtained
from 71 children, with mild-to-moderate asthma who were enrolled in a CR
immunotherapy (IT) clinical trial, prior to treatment initiation. PBMC
were stimulated with peptide pools derived from 11 CR allergens, and
CD4+ T cell responses assessed by intracellular cytokine staining.
RESULTS : Highly heterogeneous responses in T cell reactivity were
observed among participants, both in terms of the magnitude of cytokine
response and allergen immunodominance. Reactivity against Bla g 9 and
Bla g 5 was most frequent. The phenotype of the T cell response was
dominated by IL-4 production and a Th2 polarized profile in 54.9% of
participants, but IFNγ production and Th1 polarization was observed in
25.3% of the participants. The numbers of regulatory CD4+ T cells were
also highly variable and the magnitude of effector responses and Th2
polarization were positively correlated with serum IgE levels specific
to a clinical CR extract.
CONCLUSIONS : Our results demonstrate that in children with
mild-to-moderate asthma, CR-specific T cell responses display a wide
range of magnitude, allergen dominance, and polarization. These results
will enable examination of whether any of the variables measured are
affected by IT and/or are predictive of clinical outcomes.
Keywords: Allergens, Asthma, Clinical Immunology, Cockroach, T
cell