The histamine release (HR) after challenge with anti-IgE, concanavalin A, N-formyl-met-leu-phe and the calcium ionophore A23187 from 97 cord blood samples was determined by a microfiber-based assay. Maximum HR with anti-IgE showed great inter-individual variation (median: 20.5; range: 1–104 ng/ml blood), but was not significantly different from the results obtained in identically treated blood samples from 50 adults (median: 23; range: 1–93 ng/ml blood). Both the maximum HR and the sensitivity to anti-IgE were dependent on total plasma IgE content. Blood samples with plasma IgE < 0.5 IU/ml (n = 15) had significantly higher maximum HR than those with plasma IgE < 0.5 IU/ml (n = 82; median: 32 vs. 18 ng/ml blood; p < 0.01). Passive sensitization with IgE-rich atopic plasma increased the maximum HR with anti-IgE only in samples with a plasma IgE content of less than 0.5 IU/ml, although sensitivity to anti-IgE was universally increased. Preincubation with pharmacologic agents modulating the IgE-mediated HR produced effects generally similar to previous findings in adult blood. However, the effects of inhibiting the cyclooxygenase pathway in cord blood differed from our observations in adult blood, and may represent a maturational phenomenon. The familiy history of allergy was obtained by a questionnaire, and clinical observations were gathered from patient records. None of these parameters were found to influence HR with any secretagogue. However, HR stimulated by the calcium ionophore A 23187 was found to be highly dependent on the storage time of the EDTA-anticoagulated blood samples, which should be carefully controlled.

Histamine release (HR) after stimulation with anti-IgE, concanavalin A (ConA) and Formyl-Met-Leu-Phe (FMLP) from 97 cord blood samples was compared to results obtained in identically treated blood samples from adults. The maximal HR obtained with anti-IgE did not differ significantly from the values obtained in adult blood, although a ten times higher concentration of anti-IgE was required for maximum release. Passive sensitization with IgE-rich plasma caused a significant increase in maximal anti-IgE-induced HR in the majority of cord blood samples, and the dose-response curve was similar to that obtained in adult blood. Challenge with ConA and FMLP caused a HR similar to that seen in adult blood, but the close correlation between anti-IgE- and concanavalin A-induced HR seen in adult blood was absent in cord blood.

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