We studied nasopharyngeal secretions obtained from infants and young children with various forms of viral respiratory illnesses to determine the content of IL4, IL10, IFNγ and cysteinyl leukotrienes (LTs). Subjects could be classified by history and physical examination as having either upper respiratory illness (URI) alone, bronchiolitis or recurrent wheezing. Samples of secretions were obtained during the acute phase of illness and several months later when subjects were in normal health. Cytokines were measured using commercial EIA, and LTs by RIA. Group median concentrations were as shown in the table below. IL4 was the predominant cytokine in subjects with URI and during normal health. In contrast, IL4 was suppressed (and IFNγ increased) both in cases of bronchiolitis and recurrent wheezing (*p<.048, **p<.003, +p=.043). Quantities of LTs were directly correlated with IFNγ concentrations (r=.449, p=.0042). We conclude that suppression of IL4 responses during virus-induced wheezing permits excessive cell-mediated immune responses, with over-production of IFNγ. We believe IFNγ then enhances the release of LTs from eosinophils and mast cells, causing airway obstruction.

Table 1 No caption available.
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