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We are increasingly exposed to low-frequency electromagnetic fields (LF EMFs) by electrical devices and power lines, but if and how these fields interact with living cells remains a matter of debate. This study aimed to investigate the potential effect of LF EMF exposure on calcium signalling in neutrophils. In neutrophilic granulocytes, activation of G-protein coupled receptors leads to efflux of calcium from calcium stores and influx of extracellular calcium via specialised calcium channels. The cytoplasmic rise of calcium induces cytoskeleton rearrangements, modified gene expression patterns, and cell migration. If LF EMF modulates intracellular calcium signalling, this will influence cellular behaviour and may eventually lead to health problems. We found that calcium mobilisation upon chemotactic stimulation was not altered after a short 30¿min or long-term LF EMF exposure in human neutrophil-like cell lines HL-60 or PLB-985. Neither of the two investigated wave forms (Immunent and 50¿Hz sine wave) at three magnetic flux densities (5¿µT, 300¿µT, and 500¿µT) altered calcium signalling in vitro. Gene-expression patterns of calcium-signalling related genes also did not show any significant changes after exposure. Furthermore, analysis of the phenotypical appearance of microvilli by scanning electron microscopy revealed no alterations induced by LF EMF exposure. The findings above indicate that exposure to 50¿Hz sinusoidal or Immunent LF EMF will not affect calcium signalling in neutrophils in vitro.

The opioid system is involved in modulation of both innate and acquired immune responses, thus altering resistance to a variety of infectious agents. We sequenced and characterized carp opioid receptors (MOR, DOR, and KOR) and found their regulated expression in piscine leukocytes. Moreover, both in vivo and in vitro opioids affect activity of leukocytes and expression of inflammatory molecules, especially chemokines and chemokine receptors. Our data indicate an evolutionary conserved role for the opioid system in immune regulation

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The origin and function of rodlet cells (RCs) are still a matter of discussion. Whereas the exogenous hypothesis considers them parasites, the endogenous hypothesis regards them as a genuine fish cell population with a secretory and/or leukocyte function. In order to shed more light on these questions we focused on the location and appearance of RCs during carp (Cyprinus carpio) ontogeny. Typical RCs were seen at 5 days post fertilisation (dpf) between kidney and intestine, at 6 dpf in the intestine and at 8 dpf in both anterior and posterior kidney and in the abdominal cavity among the mesothelial cells. The RC number increased with age and after 14 dpf they were also present in gills. The early appearance of the RCs during carp ontogeny support the endogenous hypothesis stating that RCs are genuine constituents of fish tissue and suggest that they are `immune cells¿. The fact that the RCs of the gills secrete their content into the surrounding water, combined with the strategic location around blood vessels in kidney and within intestinal epithelium, would also support an important role in host defense. To investigate whether RC numbers in gills and kidney are related to typical fluctuations in the physiology during stress and infection we counted their number in gills and kidney after parasite infection and stress. In the gills the number of RCs increased after infection but did not change after stress while in the kidney their number increased after stress and no significant changes were observed after infection

Three novel CXC chemokines were identified in common carp (Cyprinus carpio L.) through homology cloning. Phylogenetic analyses show that one of the three CXC chemokines is an unambiguous orthologue of CXCL14, whereas both others are orthologues of CXCL12, and were named CXCL12a and CXCL12b. Percentages of amino acid identity between each of these carp chemokines and their human and mouse orthologues are markedly higher than those reported previously for other carp CXC chemokines, suggestive of involvement in vital processes, which have allowed for relatively few structural changes. Furthermore, all three novel carp CXC chemokines are expressed during early development, in contrast to established immune CXC chemokines. In noninfected adult carp, CXCL12b and CXCL14 are predominantly expressed in the brain. CXCL12a is highly expressed in kidney and anterior kidney, but its expression is still more abundant in brain than any other carp CXC chemokine. Clearly, these chemokines must play key roles in the patterning and maintenance of the (developing) vertebrate central nervous system.

Interleukin-1beta (Il-1beta) is a central component in innate immunity and the inflammatory response of mammals. Only recently, the first non-mammalian IL-1beta sequences were published. In this study, we describe a second IL-1beta sequence (IL-1beta2) in carp with 74% amino acid identity to the carp IL-1beta1 sequence. The existence of two IL-1beta copies in the carp genome probably originates from the tetraploid nature of the species. In contrast to the first carp Il-1beta sequence, IL-1beta2 is represented by multiple genes with 95-99% identity. Detection of several IL-1beta2 sequences within individual homozygous fish suggests the presence of multiple copies of the Il-1beta2 gene in the carp genome, possibly as a result of subsequent gene duplication of IL-1beta2. In vivo, constitutive mRNA expression of both IL-1beta genes was found in healthy carp. IL-1beta2 mRNA expression could be up-regulated in head kidney cells similar to carp IL-1beta1, in vivo by infection with Trypanoplasma borreli and in vitro by stimulation with lipopolysaccharide (LPS). Cortisol, the major glucocorticoid in fish, is an endocrine-derived factor mediating Il-1beta expression. Although constitutive IL-1beta expression was inhibited by a physiological dose of cortisol, cortisol synergistically enhanced LPS-induced IL-1beta expression in carp. Involvement of the transcription factor nuclear factor (NF)-kappaB in expression of IL-1beta1 and IL-1beta2 was demonstrated. Ratio of IL-1beta expression was determined and this showed IL-1beta1 mRNA expression to be at least tenfold higher compared with IL-1beta2. The possibilities of IL-1beta2 being a functional gene or approaching pseudogene status are discussed. (C) 2002 Elsevier Science Ltd. All rights reserved.