Cytokines in sera from insulin-dependent diabetic patients at diagnosis

Serum levels of interleukin-1 beta and interleukin-6 in patients with chronic pancreatitis

To investigate the role played by cytokines in chronic pancreatitis, we examined serum levels of interleukin-1 beta (IL-1 beta) and interleukin-6 (IL-6) by radioimmunoassay (RIA) and enzyme-linked immunosorbent assay (ELISA) in 33 patients with definitively diagnosed chronic pancreatitis. All the patients, who had received either no treatment or only digestive enzyme products for their chronic pancreatitis, had significantly elevated serum IL-1 beta levels (38.5 +/- 28.8 pg/ml, mean +/- SD), compared to normal controls (16.0 +/- 6.7 pg/ml; P < 0.01); however they showed no changes in serum IL-6 levels. Changes in IL-1 beta and IL-6 serum levels were not correlated with the etiological features of pancreatitis or with complications due to liver diseases. Serum IL-1 beta and IL-6 levels were also not correlated with the activity of any pancreatic enzymes in blood or urine. However, in the patients with chronic pancreatitis, serum IL-6 levels were correlated with C-reactive protein (CRP), whereas serum IL-1 beta levels were not correlated with CRP or with erythrocyte sedimentation rate. These results suggest that serum IL-1 beta is involved in the progression and reduction of chronic inflammation of the pancreas, and that the serum IL-1 beta level may be useful as a marker for chronic pancreatitis.

Cytokines and autoimmunity

Although the immunopathology of most autoimmune diseases has been well defined, the mechanisms responsible for the breakdown of self-tolerance and which lead to the development of systemic and organ-specific autoaggression are still unclear. Evidence has accumulated which supports a role for a disregulated production of cytokines by leucocytes and possibly other cells in the pathogenesis of some autoimmune diseases. However, due to the complexity and heterogeneity of cytokine effects in the regulation of the immune response, it is difficult to determine whether abnormalities in the patterns of cytokine production are primary or secondary to the pathological process. Confusion is also caused by the fact that the biological activities of cytokines are multiple and often overlapping, and consequently it is difficult to focus on a unique effect of any one cytokine. Characterization of the potential and actual involvement of cytokines is important not only for a better understanding of the pathogenesis of autoimmune conditions, but particularly because of the implications for the development of immunotherapeutic strategies for the prevention and treatment of the diseases.

High serum levels of soluble CD8 in insulin-dependent diabetes

In type 1 (insulin-dependent) diabetes mellitus (IDDM) CD8+ T cells represent the majority of lymphocytes which infiltrate the pancreatic islets during beta cell destruction. Soluble CD8 antigen (sCD8) has been shown to correlate with CD8 cell subset activation. In this study we measured by ELISA sCD8 levels in sera from: 33 newly diagnosed IDDM patients; 29 type 1 diabetics with duration of disease more than 1 year; 37 healthy siblings of IDDM patients; 19 healthy controls. Sera from both groups of IDDM patients and from healthy siblings exhibited soluble CD8 mean levels significantly higher than controls (P = 0.0001, P < 0.003, P < 0.03 respectively). Soluble CD8 levels above the normal range (mean +/- 2 s.d. of controls) were found in a percentage of newly diagnosed subjects (54.5%) significantly higher than in subjects with a long-standing duration of disease (6.9%, P < 0.0005) and healthy siblings (16.2%, P < 0.002). Our results suggest that the raised levels of soluble CD8 near to diabetes onset may indicate the activation of CD8+ T cells probably responsible for the autoimmune beta cell destruction.

Detection of tumor necrosis factor-alpha in bone marrow plasma and peripheral blood plasma from patients with aplastic anemia

Plasma levels of interferon-gamma (IFN-gamma) and tumor necrosis factor-alpha (TNF-alpha) were determined in healthy individuals and patients with aplastic anemia (ApAn). IFN-gamma was not detected in normal peripheral blood plasma (PBP) or bone marrow plasma (BMP) and was present in PBP from only 2 of 22 patients and in BMP from 1 of 14 patients and the levels were low (< 1.5 U/ml). Elevated levels of TNF-alpha were present in BMP and PBP from patients but not in control (healthy donor) PBP and BMP. Eleven of twenty-four patients had elevated levels of TNF-alpha in their PBP and 6 of 13 patients had detectable levels of TNF-alpha in their BMP. Only one of the 14 healthy control donors had detectable TNF-alpha and the level was very low (7 pg/ml), while 13 of the 27 ApAn patients had detectable TNF-alpha (P = .009, chi-square test). Not surprisingly, the centers of the distributions of TNF-alpha concentrations of the controls and ApAn patients differed significantly (P < .017 for control and patient PBP and P < .056 for control and patient BMP, Wilcoxon rank-sum test). Spontaneous production of IFN-gamma and TNF-alpha by cultured bone marrow mononuclear cells was observed in four of seven patients but not in the six healthy controls (P = 0.026). Spontaneous production of IFN-gamma and TNF-alpha by cultured peripheral blood mononuclear cells from patients and controls was however similar. Phytohemagglutinin (PHA)-induced production of IFN-gamma and TNF-alpha by cultured mononuclear cells did not differ significantly between ApAn patients and normal controls. The significance of overproduction of TNF-alpha in the pathophysiology of ApAn is discussed.

Effect of cyclosporine A on serum tumor necrosis factor alpha in new-onset type I (insulin-dependent) diabetes mellitus

Because the etiology of insulin-dependent diabetes mellitus (IDDM) is thought to be autoimmune, several clinical trials have utilized immunosuppression to treat newly diagnosed diabetic patients. In the University of Miami trial, cyclosporine A (CyA) was used to treat one group (n = 10), while the other received placebo (n = 13). During the 1-year study, islet beta-cell function was better preserved in the CyA group compared to the placebo group, based on the response (C-peptide production) to a physiologic stimulus (meal challenge). Specifically, when measured by regression analysis, the slope defining the rate of decline of beta-cell function was significantly lower for the CyA-treated group (p < 0.05). Cytokine levels were analyzed retrospectively from frozen (-70 degrees C) stored sera from both groups. At time 0, tumor necrosis factor alpha (TNF alpha) levels were similar in the CyA (40.1 +/- 14.2 pg/mL) and placebo group (38.5 +/- 12.1 pg/mL) of IDDM subjects (normal 32.0 +/- 5.0 pg/mL). At 1 month, the level of TNF alpha in the CyA group was significantly lower than that observed in the placebo group (22.3 +/- 7.2 versus 53.3 +/- 8.9 pg/mL (P < .05). TNF alpha levels subsequently fell in the placebo group and were not significantly different between placebo and CyA groups. Soluble interleukin 2 receptor (IL-2R) levels in IDDM patients were significantly higher than in normal subjects at diagnosis of IDDM. For the next 6 months, these levels fell consistently in both the CyA and placebo groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Cytokines in autoimmunity

It is now generally accepted that many cytokines are involved in the pathogenesis of autoimmune disease, either directly by causing tissue destruction or indirectly through the activation of autoreactive and inflammatory cells. Thus, cytokines, such as tumor necrosis factor-alpha, are implicated in the pathogenesis of rheumatoid arthritis based on in vitro studies on synovial tissue from patients with rheumatoid arthritis, which suggest that the effects of tumor necrosis factor-alpha are amplified by its potential to induce other pro-inflammatory cytokines, such as interleukin-1 and granulocyte-macrophage colony-stimulating factor. Transgenic mouse technology has shown that mice expressing the human tumor necrosis factor-alpha gene develop a polyarthritis. Interleukin-2 has also been identified by transgenic technology as a cytokine involved in the pathogenesis of insulin-dependent diabetes mellitus through the activation and stimulation of growth of autoreactive T cells.