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We previously described a patient with a history of frequent life-threatening pneumonias, infections with bacterial pathogens, interleukin 1 receptor-associated kinase 4 deficiency, and failure to maintain antibody titers to polysaccharide antigens or to a neoantigen bacteriophage. In the present study, we show that the patient's peripheral blood mononuclear cells have a profound deficiency of invariant natural killer T cells.

Most autoreactive B cells are normally counterselected during early B cell development. To determine whether Toll-like receptors (TLRs) regulate the removal of autoreactive B lymphocytes, we tested the reactivity of recombinant antibodies from single B cells isolated from patients deficient for IRAK-4, and MyD88, whose cells do not respond to TLRs except TLR3 and from UNC-93B-deficient patients whose cells are irresponsive to TLR3, TLR7, TLR8 and TLR9. All patients suffered from defective central and peripheral B cell tolerance checkpoints resulting in the accumulation of large numbers of autoreactive mature naïve B cells in their blood. Hence, TLR7, TLR8, and TLR9 may normally prevent the recruitment of developing autoreactive B cells in healthy donors. Paradoxically, IRAK-4-, MyD88- and UNC-93B-deficient patients do not display autoreactive antibodies in their serum nor develop autoimmune diseases revealing that IRAK-4/MyD88/UNC-93B pathways blockade is likely to thwart the development of autoimmunity in humans.

Background Mannose-binding lectin (MBL), an acute-phase serum protein of hepatic origin, plays an essential protective role in host innate immunity in targeting microbial pathogens for destruction via opsonization, enhancement of phagocytosis and complement activation. MBL deficiency, characterized by low serum MBL, has been attributed to genetic mutations in both structural and promoter regions of the gene coding for the protein. Concomitant MBL deficiency in patients with chronic immunologic disease has been associated with increased susceptibility to complicating infections that may hasten disease progression. Objective Few cases of inherited MBL deficiency in adults and possible associations with recurrent infection have been reported. To address this issue, we investigated the MBL profile of four generations within a single adult family whose members have experienced a variety of persistent infections. Methods MBL serum levels and MBL genotypes of each participating family member were ascertained by enzyme-linked immunoadsorbent assay and reverse transcriptase-polymerase chain reaction, respectively. MBL complement activation, as measured by C4b deposition against mannan-coated wells, was assayed using an enzyme-linked immunoadsorbent assay. Routine immunologic and cellular tests were carried out to evaluate the immunologic status of each family member. Results Six of the 7 family members screened carried one or more of the variant MBL alleles in their genotype and had correspondingly low serum MBL and reduced ability to affect C4b opsonization. Medical histories of the participating family members revealed an array of mild to severe recurrent infections despite no apparent immunodeficiency. Conclusions Our studies show that MBL deficiency is an inherited characteristic and may be a crucial factor in maintaining immunologic health.

Interleukin-10 (IL-10) plays an important immunopathogenic role in immunologic diseases, especially in HIV infection and atopic dermatitis. The control and regulatory mechanisms of IL-10 production have not been described in these diseases. Recently, we demonstrated that HIV-1 Nef induces IL-10 production in monocytes and that staphylococcal enterotoxin A (SEA) induces IL-10 production in T-lymphocytes. Here we show that Nef-induced IL-10 production and mRNA expression are strongly blocked by rapamycin, but are not blocked by cyclosporin (CsA) or FK506. Conversely, we show that CsA and FK506 completely inhibit SEA-induced IL-10 protein production and mRNA expression. The results of this study demonstrate that IL-10 production by Nef and SEA is controlled and regulated by different mechanisms.

X-linked hyper IgM syndrome (XHIM), caused by mutations of the CD40 ligand (CD40L) gene, is characterized by recurrent bacterial and opportunistic infections, an increased incidence of autoimmunity and malignancies, and immunodeficiency due to abnormal T/B cell interaction. Because of poor long-term prognosis, bone marrow transplantation (BMT) has been proposed as an alternative treatment. An 8-month-old boy with XHIM and a splice site mutation of CD40L underwent BMT using a fully matched sibling donor. Markers of engraftment and immunologic reconstitution were measured serially. After BMT, activated T cells expressed functional CD40L, and genomic DNA obtained from circulating white cells contained predominantly wild-type CD40L sequences. Serum immunoglobulin levels including IgE and antibody responses to recall antigens normalized, and immunization with the T-cell-dependent neoantigen, bacteriophagephi;X174, demonstrated amplification of the response and isotope switching. BMT provides a permanent cure for XHIM if a fully matched sibling donor is available and the procedure is performed before complications have occurred.

The effects of recombinant gp41 (rgp41) protein of the human immunodeficiency virus type 1 (HIV-1) on interleukin 10 (IL-10) expression and production using human peripheral blood mononuclear cells was investigated. Expression of IL-10 mRNA was demonstrated within 3 h of cell exposure to endotoxin-free rgp41 by RT-PCR and Northern blot analyses in a time- and dose-dependent manner. IL-10 protein was detected in the supernatants of peripheral blood mononuclear cells following stimulation with rgp41 also in a dose dependent manner. Fractionation of peripheral blood mononuclear cells showed that purified monocytes but not purified T-lymphocytes induced expression of IL-10 mRNA by rgp41. Recombinant HIV-1 gp120 exhibits similar influences on the induction of IL-10. These results indicate that both of these components of envelope proteins may play an important role in HIV related immunomodulation by influencing regulatory functions of monocytes and macrophages.

We previously described a girl with recurrent episodes of pneumococcal pneumonia with septicemia and other infections,(1) found to have interleukin-1 receptor-associated kinase 4 deficiency (IRAK-4) deficiency.(2) In this report, we show that our patient is unable to sustain antibody responses either to polysaccharide or protein antigens or to a neoantigen-bacteriophage.

The mechanism(s) by which retroviral proteins exert immunosuppressive influences has remained enigmatic. Here, Soichi Haraguchi, Robert Good and Noorbibi Day propose that induction of intracellular cAMP by a synthetic, immunosuppressive, retroviral envelope peptide causes a shift in the cytokine balance, leading to suppression of cell-mediated immunity by upregulation of interleukin 10 (IL-10) and downregulation of IL-2, IL-12 and tumor necrosis factor α production. This may be a crucial step towards generation of immune dysfunction.

We have previously shown that a human mammotropic polypeptide hormone, prolactin (PRL) can act synergistically with steroid hormones to regulate gene expression directed by the long terminal repeat of mouse mammary tumor virus (MMTV LTR) in a human ductal carcinoma cell line T47D cells using a chloramphenicol acetyltransferase reporter gene system and gene transfection methods. In the present study, using various recombinant plasmids we analyzed functional elements in the MMTV LTR that is essential for the PRL responses. We show that the PRL-responsive elements are located in the extreme 5' end of the MMTV LTR, a region previously described by others to be a mammary cell-specific enhancer.

CKS-17, a synthetic amino acid peptide homologous to a highly conserved region of retroviral transmembrane protein exerts a suppressive action on staphylococcal enterotoxin A (SEA)-induced the production of IFN-γ by human peripheral blood mononuclear cells (PBMC) (Ogasawara et al., J. Immunol. 141 , 615, 1988). This action has been shown in the present study to be preceded by dramatic clustering of PBMC. Clusters appear within 3 hr of exposure of PBMC to CKS-17; they are dose dependent, inhibited by cycloheximide, and require a temperature of 37 °C. The cells in the clusters are predominantly monocytes. Although it has been previously shown that CKS-17 inhibits monocyte-mediated killing by inactivating IL-1 (Kleinerman et al., J. Immunol. 139 , 2329, 1987) and production of IL-2 by murine thymoma cells treated with IL-1 (Gottlieb et al., J. Immunol. 142 , 4321, 1989), in the present study we show that IL-1 does not prevent clustering of PBMC by CKS-17. Using CKS-17 and highly purified monocytes or lymphocytes, profound alterations occur only with monocytes, as revealed by light or electron microscopy. SEA- or staphylococcal enterotoxin B-induced production of IFN-γ is inhibited when highly purified monocytes pretreated with CKS-17 are cocultured with highly purified T lymphocytes. Thus, CKS-17 induces dramatic clustering of cells apparently by inducing alterations of monocytes but not lymphocytes, suggesting that CKS-17 may interfere with the capacity of monocytes to facilitate production of IFN-γ by T lymphocytes.

Rationale HIV-1 co-receptors, CXCR4 and CCR5, are essential for HIV entry and its life cycle. Expression of CXCR4 on T-lymphocytes is lower during HIV-infection and is normalized by antiretroviral therapy. We propose that HIV-1 Nef, an important HIV-1 regulatory protein, may play an important role in HIV-1 co-receptor expression on T lymphocytes during HIV infection. Methods CXCR4 and CCR5 expression on CD4 + T-lymphocytes was measured using quantitative flow cytometric assay in 23 HIV-infected children and 10 healthy subjects after 24-hour in vitro stimulation with various HIV-1 regulatory proteins (Nef 100 ng/ml, Tat 1 ng/ml, Gag 500 ng/ml, and gp120IIIB 250 ng/ml). Results Without HIV-1 regulatory protein stimulation, mean CXCR4 expression on CD4 + T-lymphocytes was significantly higher in healthy subjects compared to HIV-infected children (36.79% vs 24.60%; p=0.005). Following 24-hour incubation with Nef, mean CXCR4 expression on T-lymphocytes of healthy subjects was significantly decreased when compared to the expression on cells without stimulation (30.38% vs. 36.79%; p=0.012). There was no longer significant difference in mean CXCR4 expression on T-lymphocyte between HIV-infected children and healthy subjects after Nef stimulation (24.81% vs. 30.4%; p=NS). There was no significant change in mean CXCR4 expression on T-lymphocytes after stimulation with other HIV-1 proteins in HIV-infected children or healthy subjects. No significant change in the CCR5 expression on CD4 + T-lymphocytes was seen after stimulation with various HIV-1 proteins. Conclusions HIV-1 Nef protein decreases CXCR4 expression on CD4 + T-lymphocytes in healthy subjects. This may be an important mechanism for CXCR4 down-regulation during HIV-1 infection.