Soluble interleukin-4 receptor production by murine myeloid progenitor cells: induction by interleukin-6 and interferon-gamma

Impaired T-lymphocyte proliferation function in biliary atresia patients with chronic cholestatic jaundice after a Kasai operation

To investigate the association between chronic cholestatic jaundice, systemic immunity, and various infectious complications in patients with biliary atresia (BA), we performed a survey of the systemic immune function in 30 children with BA. Patients were divided into a jaundice group (total serum bilirubin > or = 2 mg/dL for >6 mo) and control group (total serum bilirubin <2 mg/dL for >6 mo) with comparable age. Patients were tested for serum immunoglobulin and complement levels, mitogen response, interleukin (IL)-4, IL-5, and interferon-gamma production after phytohemagglutinin (PHA) stimulation, blood cell and lymphocyte subpopulation counts, phagocytic function, and leukocyte adhesion complex. They were then followed prospectively for 6 mo, and severe infectious complications requiring hospitalization were recorded. Compared with jaundice-free patients, T-lymphocyte proliferation function, determined by PHA mitogen test was significantly lower (p = 0.02) in BA patients with chronic cholestatic jaundice after a Kasai operation. During the study period, patients with chronic cholestatic jaundice had a higher risk of severe infectious complications than their jaundice-free counterparts (risk ratio = 5.87; p = 0.001). In conclusion, BA patients with chronic cholestatic jaundice are associated with impairment of T-lymphocyte proliferation and increased incidence of severe infectious complications.

Cytokines and soluble cytokine receptor induction after IL-12 administration in cancer patients

This study shows that subcutaneous administration of increasing doses of IL-12, once a week, in 21 cancer patients increased the expression of cytokine genes (interferon-gamma (IFN-gamma), tumour necrosis factor-alpha (TNF-alpha), IP-10, MIG, IL-10, IL-4) in peripheral blood mononuclear cells even at very low doses (30 ng/kg). Surprisingly, no circulating TNF-alpha or IL-4 could be detected in the plasma of patients treated with IL-12. However, a marked increase of soluble IL-4 receptor was demonstrated in the plasma of five of the six patients studied, which may represent an additional mechanism by which IL-12 inhibits the development of the Th2 response in vivo. A marked decline of IFN-gamma and IP10 induction was recorded after repeated cycles of IL-12. In contrast, in most patients IL-12 increased IL-10 expression with no subsequent decrease during the course of therapy, and even an earlier peak of IL-10 induction at the 6th cycle. In addition, a constant up-regulation of serum soluble IFN-gamma receptor levels was observed after each cycle of IL-12 treatment with a delayed peak compared with the IFN-gamma peak. The constant rise of IL-10 and soluble IFN-gamma receptor during IL-12 therapy may therefore contribute to the inhibition of IFN-gamma activity detected after repeated cycles of IL-12. Lastly, a marked heterogeneity of cytokine induction was observed from one patient to another, which appeared to be independent of the dose of IL-12 administered. These data may lead to a better understanding of the biological activity of IL-12 and the in vivo mechanisms of its regulation.

Linked in vivo expression of soluble interleukin-4 receptor and interleukin-4 in murine schistosomiasis

Soluble interleukin-4 receptors (sIL-4R) are truncated IL-4R molecules that are secreted into biological fluids. To gain an insight into the mechanisms that control sIL-4R synthesis in vivo and their role in the regulation of immune responses, the expression and secretion of sIL-4R in mice infected with Schistosoma mansoni was studied. Splenocytes from infected animals responded to schistosomal antigen preparations with increased production of both IL-4 and sIL-4R. The synthesis of sIL-4R by spleen cells peaked at 8 weeks following infection and coincided with maximum levels of sIL-4R in serum and sIL-4R-specific mRNA in the liver of infected mice. The expression of IL-4-specific mRNA in the liver was different from that of IL-4R, reaching its peak approximately 2 weeks earlier. A relationship between sIL-4R production and the development and activation of Th2 cells was suggested by the findings that: (a) in vivo administration of anti-IL-4 antibodies (11B11) impaired the ability of splenic cells to secrete either IL-4 or sIL-4R; and (b) splenic cells from mice vaccinated with irradiated cercariae, which tend to develop much weaker Th2 responses than mice injected with live cercariae, expressed reduced levels of sIL-4R when challenged with schistosomal antigens. Moreover, a direct role for IL-4 in regulating the expression of sIL-4R was suggested by the ability of anti-IL-4 antibodies to inhibit sIL-4R synthesis in vitro. These data provide the first evidence demonstrating that the production of sIL-4R in vivo is up-regulated during immune responses, especially during those characterized by the development and activation of Th2 cells and IL-4 secretion. The association between sIL-4R and IL-4 synthesis is consistent with a potential role for sIL-4R in the regulation of IL-4 activity in vivo.

Anti-cytokines: promising tools for diagnosis and immunotherapy

Anti-cytokines belong to a new family of biological response modifiers which interfere with the biological functions of cytokines. An imbalance between cytokines and natural anti-cytokines may represent an important factor to explain the pathogenesis of some human diseases. Indeed, dysregulation of anti-cytokine serum levels was observed in cancers and auto-immune and infectious diseases. It was sometimes associated with disease activity and in some circumstances they may help to predict clinical response to treatment. Control of disease activity in septic shock and auto-immune diseases was demonstrated after administration of anti-cytokines such as soluble TNF receptors and IL1ra inhibitors. Therefore these agents are promising tools for diagnosis and immunotherapy.