Recombinant human IL-1α and -1β potentiate IgE-mediated histamine release from human basophils

In this study, we have explored the relationship between interleukins and human basophil activation. Previous studies by ourselves and others have found that recombinant human (rh) IL-3 causes histamine release. The ability to release histamine has also been claimed for IL-1 but we cannot confirm this. In experiments with the basophils of 29 donors (excluding one D₂O responder), histamine release with 100 ng/ml rhIL-1α was 1.3 ± 1% (SEM), whereas with rhIL-1β, it was 0.8 ± 1%. Both IL-1α and -1β were also used at concentrations of 0.01 to 1000 ng/ml without causing release. Neither increasing the Ca²⁺ concentration nor adding D₂O or cytochalasin B caused IL-1α and -1β to become secretagogues. rhIL-1, however, did augment IgE-dependent histamine release. The enhancement was similar with both rhIL-1α and -1β, i.e. they were dose-dependent between 0.1 and 3 ng/ml and reached a plateau from 3 to 100 ng/ml. At submaximal histamine release (<10%), there was enhancement of three IgE-dependent secretagogues: 125% with goat anti-human IgE (n = 7), 215% with Ag E (n = 19), and 260% with a histamine releasing factor (n = 7). Non-IgE-dependent stimuli (formyl-methionine-leucine-phenylaline and the ionophore A23187, n = 10) were enhanced <5%. rhIL-1-enhancement persisted after cell washing (n = 10). rhIL-1 was active in preparations of 50 to 75% pure basophils in which mononuclear cells were reduced by >95% (n = 4), and mAbH34 to IL-1β blocked the enhancement caused by that molecule. We postulate that basophils have an IL-1 receptor which, when occupied, upregulates the response to IgE-related signals. Thus, this work characterizes a second interaction between interleukins and the cells central to the allergic response.