Recently, we isolated some new and functionally identical panchemotactic factors (Lipid-like leucocyte activators = LILAs) from Candida albicans, Saccharomyces cerevisiae and various dermatophytes, which are chemotactic for human neutrophilic and eosinophilic granulocytes as well as for monocytes. In order to answer the question, whether human neutrophilic granulocytes express a specific receptor for LILA, we now investigated the mobilisation of the intracellular second messenger calcium within human neutrophils which were stimulated with LILA. Furthermore, LILA-mediated activation of neutrophils was subjected to desensitisation experiments with the well known neutrophil activators 5-oxo-eicosatetraenoic acid, leukotriene B4, platelet activating factor, C5a, Interleukin-8, and N-for-myl-methionyl-leucyl-phenylalanin (FMLP). The intracellular calcium concentration was measured by use of the fluorescence indicator FURA-2/AM. As a result we were able to show a significant dose-dependent increase in the intracellular calcium concentration after stimulation of human neutrophils with LILA. The desensitisation experiments revealed no cross-desensitisation between LILA and the well known stimuli. Our results show that LILA induces an intracellular calcium signal in addition to its panchemotactic activities. Therefore, calcium may act as second messenger in LILA-stimulated activation of neutrophils. Since LILA-mediated activation was maintained in the desensitisation experiments, LILA-specific receptors may be present on human neutrophils.