Immune Responses In Healthy Individuals Research Articles

Functional regulatory immune responses against human cartilage glycoprotein-39 in health versus proinflammatory responses in rheumatoid arthritis

The class of immune response against autoantigens could profoundly influence the onset and/or outcome of autoimmune diseases. Until now, there is only limited information on the antigen-specific balance between proinflammatory and regulatory responses in humans. Here we analyzed the natural immune response against a candidate autoantigen in rheumatoid arthritis, Human Cartilage gp-39 (HC gp-39). Peripheral blood mononuclear cells from healthy individuals reacted against HC gp-39 with the production of IL-10, but not interferon gamma (Fig. ​(Fig.1).1). Ex vivo assays indicated that the naturally occurring HC gp-39-specific immune response in bulk is powerful enough to suppress antigen-specific recall responses, demonstrating that, rather than being unresponsive, the HC gp-39-directed immune response in healthy individuals shows a strong bias towards a regulatory phenotype. Moreover, CD4+ T-cell lines directed against HC gp-39 expressed CD25, GITR and Foxp3 molecules and were capable of suppressing antigen-specific T-cell responses. Cell–cell contact was required for this suppression. As opposed to healthy individuals, the HC gp-39-directed immune response in 50% of patients with rheumatoid arthritis exhibits polarization towards a proinflammatory Th1 phenotype and is significantly less powerful in suppressing antigen-specific recall responses. Figure 1 Human Cartilage gp-39 (HC gp-39)-specific immune reactivity in healthy donors. (a) Peripheral blood mononuclear cells from healthy donors (n = 31) react against HC gp-39 by production of IL-10 but not interferon gamma (IFN-γ). (b) 'Control' recall ... Together these findings indicate that the presence of HC gp-39-specific immune responses in healthy individuals may have an inhibitory effect on inflammatory responses in areas where HC gp-39 is present. Furthermore, these data indicate that the class of HC gp-39-directed immune response in RA patients has shifted from an anti-inflammatory towards a proinflammatory phenotype.

Functional regulatory immune responses against human cartilage glycoprotein-39 in health vs. proinflammatory responses in rheumatoid arthritis.

The class of immune response against autoantigens could profoundly influence the onset and/or outcome of autoimmune diseases. Until now, there is only limited information on the antigen-specific balance between proinflammatory and regulatory responses in humans. Here we analyzed the natural immune response against a candidate autoantigen in rheumatoid arthritis, human cartilage glycoprotein-39 (HC gp-39). Peripheral blood mononuclear cells from healthy individuals reacted against HC gp-39 with the production of IL-10 but not IFN-gamma. Ex vivo assays indicated that the naturally occurring HC gp-39-specific immune response in bulk is powerful enough to suppress antigen-specific recall responses, demonstrating that rather than being unresponsive, the HC gp-39-directed immune response in healthy individuals shows a strong bias toward a regulatory phenotype. Moreover, CD4(+) T cell lines directed against HC gp-39 expressed CD25, glucocorticoid-induced tumor necrosis factor receptor, and Foxp3 molecules and were capable of suppressing antigen-specific T cell responses. Cell-cell contact was required for this suppression. As opposed to healthy individuals, the HC gp-39-directed immune response in 50% of patients with rheumatoid arthritis exhibits polarization toward a proinflammatory T helper 1 phenotype and is significantly less powerful in suppressing antigen-specific recall responses. Together these findings indicate that the presence of HC gp-39-specific immune responses in healthy individuals may have an inhibitory effect on inflammatory responses in areas where HC gp-39 is present. Furthermore, these data indicate that the class of HC gp-39-directed immune response in rheumatoid arthritis patients has shifted from an antiinflammatory toward a proinflammatory phenotype.

Beryllium-specific immune response in primary cells from healthy individuals.

The effect of beryllium (Be) exposure has been extensively studied in patients with chronic beryllium disease (CBD). CBD patients carry mutated MHC class II alleles and show a hyperproliferation of T cells upon Be exposure. The exact mechanism of Be-induced T-cell proliferation in these patients is not clearly understood. It is also not known how the inflammatory and suppressive cytokines maintain a balance in healthy individuals and how this balance is lost in CBD patients. To address these issues, we have initiated cellular and biochemical studies to identify Be-responsive cytokines and other cellular markers that help maintain a balance in healthy individuals. We have established an immune cell model derived from a mixture of peripheral blood mononuclear cells (PBMCs) and dendritic cells (DCs). In this article, we demonstrate that pro-inflammatory cytokine IL6 shows decreased release whereas suppressive cytokine IL10 shows enhanced release after 5-10 h of Be treatment. Furthermore, the Be-specific pattern of IL6 and IL10 release is dependent upon induction of threonine phosphorylation of a 45 kDa cytosolic protein (p45), as early as 90 min after Be treatment. Pharmacological inhibition of phosphatidylinositol 3' kinase (PI3'K) by wortmannin and p38 mitogen-activated protein kinase (MAPK) by SB203580 reveal that PI3'K mediates Be-specific p45 phosphorylation and IL6 release, whereas p38 MAPK regulates the release of IL6 and IL10 and the phosphorylation of p45 independent of metal-salt treatment. While the IL10 and IL6 release pathways are uncoupled in these cells, they are linked to phosphorylation of p45. These findings suggest that the balance between IL10 and IL6 release and the correlated p45 phosphorylation are important components of the Be-mediated immune response in healthy individuals.

Cellular-based immune modulation in arthritis

While the symptoms associated with rheumatoid arthritis (RA) are well described, the factors that are crucially involved in induction and/or progression of RA are poorly defined. Nonetheless, it is generally accepted that cells belonging to the adaptive immune system (i.e. B cells and T cells) are intimately engaged in the processes responsible for RA induction and/or progression. As these cells require triggering of their antigen receptors before they can exert their functions, it is likely that antigen recognition is important in the pathological processes driving RA. Unfortunately, no antigens casually related to the induction/perpetuation of RA are known. Nonetheless, studies addressing the question of how immunity against autoantigens is regulated, combined with studies aiming at defining the molecular identity of antigens involved in disease, will be important to gain a better understanding of the pathways involved in the induction/progression of RA. Recently, we have found that CD4+CD25+regulatory T cells play a pivotal role in the control of arthritis in mice. More importantly, treatment of established arthritis by adoptive transfer of these cells stopped further progression of disease. These data indicate the feasibility to inhibit ongoing disease by specific manipulation of the immune system. The data described also indicate that the class of immune response against autoantigens could profoundly influence the susceptibility for, and/or outcome of, autoimmune responses. However, until now, there has been only limited evidence for autoantigen-specific regulatory responses in humans. Here we analyzed the natural immune response against Human Cartilage gp39 (HC-Gp39), a candidate autoantigen in RA. Peripheral blood mononuclear cells from healthy individuals reacted against HC Gp39 with the production of IL-10, but not interferon gamma. Ex vivo assays indicated that the natural occurring HC Gp39-directed immune response in bulk is capable of suppressing cytotoxic T-cell and recall responses, indicating that, rather than being unresponsive, the HC Gp39-directed immune response in healthy individuals is biased towards a regulatory phenotype. Moreover, CD4+ T-cell lines directed against HC Gp39 expressed CD25, GITR, CTLA-4 and Foxp3 molecules and were capable of suppressing other immune responses. Cell–cell contact was required for this suppression. In contrast, the quality of the HC Gp39-directed immune response in patients with RA exhibits polarization toward a proinflammatory Th1 phenotype. Together these findings indicate that the presence of HC Gp39-specific immune responses in healthy individuals may have a profound inhibitory effect on inflammatory responses in areas were HC Gp39 is present, and imply that the balance of autoreactive proinflammatory and antiinflammatory HC Gp39-directed immune responsiveness is disrupted in RA patients.

Cell-mediated immune reactions to human tumors.

Cell-mediated immune reactions to tumors, as demonstrated by skin testing or different in vitro procedures, occur in a large variety of human neoplastic diseases. Studies of the cytotoxic effects of patients' blood lymphocytes constitute the most widely used in vitro test system. However, while these tests provide some evidence for the occurrence of disease-related lymphocyte reactions in cancer patients, the results are controversial. The problems involved may be illustrated by results of an analysis of lymphocyte cytotoxicity in human urinary bladder carcinoma. Here lymphocyte cytotoxicity to tumor cells reflects very frequently the individuals' responses against a variety of antigens expressed to different degrees on tumor cells of different types. While some of these antigens probably are tumor-associated, others are not and may give rise to immune responses in healthy individuals as well. Moreover, the response pattern varies in different individuals with the course of disease and after therapy. For this reason, disease-related reactions may well be detected in selected groups of patients but not readily in individual cases. This presently restricts the usefulness of the assay in use as prognostic or diagnostic tool for monitoring cancer patients. That cell-mediated cytotoxicity reflects activities of both antibody dependent and antibody independent effector cells further complicates the problem. Thus, cytolysis in vitro of allogeneic tumor cells is frequently mediated by patients' lymphocytes acting in conjunction with humoral antibodies. On the other hand, as in certain experimental tumor systems, specific antibody-independent T cells may well be the effector cells when autochtonous tumor cells are the target cells. In these instances one would expect that other, more strictly tumor-specific antigens are involved in the reactions than in antibody-dependent cellular cytotoxicity. In addition, antibody-independent effector cells that kill tumor cells in a relatively nonselective manner may also be involved. Since these different mechanisms surely differ in importance for defence against tumor growth, further elucidation of the nature of effector cells and of the specificity of the cytotoxic reactions during different phases of disease appears indicated. This is particularly important when one considers the manipulation of the patients' response against their tumors by means of immunotherapy. Cancer 40:448–457, 1977.