IL-4 supplemented B-cell cultures of allergic children show reduced IgA and IgG production in response to additional stimulation with IL-10.

BACKGROUND: Cytokines play an important role in mediating immunoglobulin switch, the secretion of protective mucosal immunoglobulins, and the development of allergic diseases. This study investigates whether B cells from allergic and healthy children have different capacities to secrete immunoglobulins after stimulation with IL-4, IL-6, IL-10, IL-11, and IL13. METHODS: We analyzed the peripheral venous blood of 44 healthy probands and of 109 allergic patients with a mean age of 13 years, allergic to grass pollen, birch pollen, and house dust mites. Lymphocytes were isolated by a density gradient and B cells were enriched by using a Magnetic Activated Cell Separator (MACS) and anti-CD19 microbeads. B Cells were co-cultured with human CDw32 (Fc gammaRII) expressing mouse Ltk fibroblasts and mouse anti-human CD40 monoclonal antibodies (CD40 system). The interleukins IL-4, IL-6, IL-10, IL-11, and IL-13 were supplemented in various combinations. After 14 days, concentrations of IgE, IgG, IgA, and IgM were measured in the supernatants with ELISA. RESULTS: Suppression of IgA-, IgG, and IgM- synthesis was induced by stimulation of B cells with IL-4. After additional application of IL-10, IgA, IgG, and IgM synthesis was significantly increased. When cultures stimulated with IL-4 were additionally supplemented with IL-10, IgA, and IgG synthesis of B cells obtained from allergic individuals was significantly decreased compared to nonallergic individuals. IgE-secretion of B cells from allergic individuals was significantly increased compared to nonallergic individuals after stimulation with IL-4. CONCLUSION: Our results implicate that IL-4 is essential for the regulation of immunoglobulin class switch to IgE and that IL-4 is an important cytokine for the development of allergic diseases. The capacity of B cells in allergic children to produce less IgA and IgG in response to additional stimulation with IL-10 of cultures supplemented with IL-4 could play an important role in mediating a mucosal immune system vulnerable to allergens. This phenomenon could contribute to the pathogenesis of allergic diseases.

Effects of intrahippocampally-injected naloxone and morphine upon behavioural responses to novelty in mice from two selectively-bred lines.

To examine the peptidergic regulation of behavioural responses to novelty, 5-month-old male mice from the inbred selection lines SRH (selected for rearing frequency: high) and SRL (selected for rearing frequency: low) were intrahippocampally micro-injected (0.5 microliter) with either the opiate antagonist naloxone (0.3 microgram), or the opiate agonist morphine (1.0 microgram), or saline vehicle alone, given 15 min prior to individual exposure to 20-min exploration tests in a novel environment. Naloxone exerted opposite effects upon various exploratory acts and locomotor activity in the two strains, that is, it decreased the scores in SRH and augmented them in SRL, while morphine depressed the scores in both. It is suggested that an excess of opioids in SRL, as compared to SRH, is attenuated by this dose of naloxone. In addition to previously obtained evidence of a genotype-dependent cholinergic mechanism in the mouse dorsal hippocampus controlling exploratory responses to novelty, these findings indicate that hippocampal opioid peptides are also involved in the genotype-dependent regulation of exploration.