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The n-3 polyunsaturated fatty acids (PUFA) appear to have antiinflammatory properties that can be partly explained by their biological activity on leukocytes. Since leukocyte emigration is an essential component of the inflammatory response, we have examined the effects of the n-3 PUFA (eicosapentaenoic and docosahexaenoic acids) on neutrophil random and chemotactic movement. Preexposure of neutrophils for 15-30 min to 1-10 micrograms/ml PUFA reduced the random and chemotactic migration to both FMLP- and fungi-activated complement. The inhibitory effect diminished with increasing saturation and carbon chain length, and methylation abolished this activity. Arachidonic and docosahexaenoic acids were the most active fatty acids. The PUFA concentration required to inhibit migration was dependent on cell number, suggesting that the fatty acid effects on leukocyte migration in vivo may be governed by the stage of the inflammatory response. It was concluded that the PUFA rather than their metabolites were responsible for the inhibition since: (a) antioxidants did not prevent the PUFA-induced migration inhibition and the hydroxylated intermediates were less active, and (b) inhibitors of the cyclooxygenase and lipoxygenase pathways were without effect. Inhibitors of protein kinases and calmodulin-dependent enzyme system did not prevent the PUFA-induced migration inhibition, which was also independent of phospholipase D-catalyzed hydrolysis of phospholipids. It is also shown that PUFA decrease the FMLP-induced Ca2+ mobilization.

Previous studies have suggested that, in vivo, activated T lymphocytes and neutrophils are important in immunity to nontypable Haemophilus influenzae. We now extend this work by showing that neutrophils pretreated with products of activated T lymphocytes or activated macrophages show significantly enhanced killing of nontypable H. influenzae. Lymphotoxin, a product of activated T lymphocytes, significantly enhanced the neutrophil-mediated killing of nontypable H. influenzae, and tumor necrosis factor, produced by activated T lymphocytes as well as macrophages stimulated by activated T lymphocytes, also significantly increased the bactericidal activity of neutrophils. These cytokine-induced effects were seen with short pretreatment times of neutrophils and were maximal by 30 min. The killing of H. influenzae by neutrophils required the presence of heat-labile opsonins. In the absence of these opsonins, both tumor necrosis factor and lymphotoxin were unable to promote the killing of the bacteria by neutrophils. Furthermore, the results showed that tumor necrosis factor-primed neutrophils displayed significantly increased expression of CR3 and CR4 that was associated with increased phagocytosis of complement-opsonized nontypable H. influenzae. These cytokines may play an important role in immunity toward nontypable H. influenzae by stimulating neutrophil bactericidal activity.

IgE and IgG antibodies to bee venom were measured in sera of patients receiving bee venom immunotherapy. All patients selected for therapy had suffered severe reactions to bee stings. The results showed that within 2–3 months from the commencement of immunotherapy there was a marked rise in IgG antibodies and a slight but not significant rise in IgE antibodies. After this period, the IgE antibody level began to fall and was about one third of the pre-treatment level by the second to third year. The IgG antibody level began to decline from its increased level after 9–10 months but remained above the pre-treatment level even after 2 years. All of the patients who had subsequently been accidentally stung after reaching the maintenance dosage of bee venom allergen showed no severe reactions. A small group of non-treated patients of the same category as those receiving therapy did not show a rise but a decline in the level of IgG antibodies. However, like the treated group, they showed a significant decrease in IgE antibodies. Thus one of the main benefits of bee venom immunotherapy is the build-up of a high concentration of IgG antibodies, and this may be the critical factor in the protection against bee venom allergy.

Children with advanced portal hypertension usually have splenomegaly (often associated with hypersplenism) which may lead to a decreased life span of circulating blood leukocytes. In a group of 6 children (age range 4–15 years; mean age 8.5 years) with portal hypertension, we examined peripheral blood mononuclear leukocytes for possible changes in their proportions, numbers and function. Compared to normal subjects, children with portal hypertension had a marked reduction in the percentages and absolute numbers of T lymphocytes (CD3+), T ‘helper/inducer’ (CD4+) and T ‘suppressor/cytotoxic’ (CD8+) cells. However, the percentages of B lymphocytes (FMC1+), natural killer cells (Leu 11+) and monocytes (morphological) were increased, and the absolute numbers of B cells were significantly increased in these patients. Lymphocyte responsiveness to phytohemagglutinin, pokeweed mitogen and concanavalin A were depressed in the patients, while the natural killer cell cytotoxicity was slightly increased. Thus, children with portal hypertension show changes in the relative proportions and absolute numbers of peripheral blood mononuclear blood leukocyte subpopulations as well as changes in mononuclear leukocyte function.

Recombinant human tumour necrosis factor alpha (rHuTNFα) was shown to inhibit human neutrophil migration in the presence or absence of a chemotactic gradient generated with the tripeptide, N-formyl-L-methionyl-L-leucyl-L-phenylalanine (fMLP), at doses of 20–100 U/106 cells. In contrast, neither recombinant human interleukin-1 alpha (rHuIL-1α), rHuIL-1β, human leucocyte-derived IL-lα (lHuIL-lα) nor lHuIL-1β contained neutrophil migration inhibition properties. However, both the interleukins (lHuIL-1α, lHuIL-1β and rHuIL-1α) and rHuTNFα stimulated a neutrophil respiratory burst and significantly elevated the neutrophil respiratory response to fMLP (measured as chemiluminescence and H2O2 production). The stimulatory effects were observed at doses of between 5 and 100 U/5 × 105 cells. A characteristic feature of the effects of the cytokines was the range of variation observed in neutrophil responses from different individuals. However, a concentration-related effect was observed with each experiment, delineating suboptimal, optimal and supra-optimal cytokine concentrations. Neutrophils treated with rHuTNFα and rHuIL-1α and washed free of exogenous cytokine retained the capacity to show an enhanced response to fMLP. Pretreatment of cells with cytochalasin B enhanced their response to fMLP, and this response was further increased if the cells had also been pretreated with the cytokines. The response to phorbol myristate acetate was also enhanced by rHuTNFα and rHuIL-1α. The effects of these cytokines on neutrophils could be abolished by boiling the preparation but not by treating it with polymixin B, suggesting that bacterial lipopolysaccharide was not responsible for the activity of these preparations. The rHuIL-1α increased the release of lysozyme, β-glucuronidase and myeloperoxidase initiated by cytochalasin B/fMLP, while rHuTNFα only increased lysozyme release.