Activation of thymocytes and T cells by interleukin-6

Interleukin 1 alpha and beta production by cells isolated from membranes around aseptically loose total joint replacements

Aseptic loosening of joint prostheses is accompanied by local osteolysis. To determine whether local production of interleukin 1 might contribute to such lysis, the number of interleukin 1 secreting cells in the pseudosynovial membrane surrounding prostheses was measured. Interleukin 1 alpha and beta secreting cells were identified by ELISPOT, a sensitive cytokine secreting assay. The proportion of interleukin 1 beta secreting cells in pseudosynovial membrane was comparable with the proportion occurring in the synovium of patients with rheumatoid arthritis and higher than that in normal subjects and patients with osteoarthritis. The proportion of interleukin 1 alpha producing cells was higher in pseudosynovial membrane than in diseased synovium. Overall, higher numbers of interleukin 1 beta than interleukin 1 alpha secreting cells were detected. A correlation was observed between the number of cells in pseudosynovial membrane producing interleukin 1 beta and those producing interleukin 1 alpha. When divided into area of origin, tissue samples from the femoral area contained a higher proportion of interleukin 1 beta producing cells than tissue in the acetabular or capsular regions, though due to variance within each group this difference did not reach significance.

Elevated circulating levels of interleukin-6 in patients with chronic renal failure

In a previous study, we demonstrated the presence of circulating interleukin-1 (IL-1) in long-term dialyzed patients and that of tumor necrosis factor alpha (TNF alpha) in both long-term and not yet dialyzed uremic patients. In the present study, we attempted to determine the respective influence of hemodialysis (HD) and uremia on the plasma level of interleukin-6 (IL-6), which shares several biological properties with IL-1 and TNF alpha, including the induction of the acute phase response of the inflammatory process. Forty-eight patients with end-stage renal failure, including 32 long-term HD patients and 16 chronic uremic patients undergoing their first dialysis session, were tested for plasma IL-6 using both biological and immunoreactive assays. Plasma IL-6 activity was significantly increased in patients with chronic renal failure (P less than 0.001) compared to its level in normal individuals. No difference was observed, however, between long-term and not yet dialyzed patients. In the patients with the most pronounced IL-6 activity, immunoreactive IL-6 levels between 60 and 150 pg/ml were detected. A monoclonal antibody (mAb) against human IL-6 inhibited the activity of plasma in the IL-6 bioassay, and a close correlation existed between the biological activity of IL-6 and its immunoreactive level. No change in plasma IL-6 was detected during the course of the first dialysis as well as subsequent sessions. Likewise, no influence of the nature (cellulosic or synthetic polyacrilonitrile) of the dialysis membrane equipping the dialyzer was observed.(ABSTRACT TRUNCATED AT 250 WORDS)

The effects of interleukin-6 on tumor-infiltrating lymphocytes derived from human renal cell cancer

Tumor-infiltrating lymphocytes (TIL) are a heterogeneous population of T cells with potent antitumor activity against a wide variety of tumors. TIL from renal cell cancer (RCC) typically exhibit diminished growth and antitumor activity after four weeks in vitro. We have therefore investigated effects of varying doses of interleukin-6 (IL-6) (0, 25, 100 units/ml.) on in vitro expansion, proliferation, cytotoxicity, and expression of cell surface phenotypes of long term renal TIL cultures from three RCC patients. Among the various conditions tested, three of three TIL cultures displayed a mild increase in cell expansion when grown in IL-2 with the addition of 100 units/ml. of IL-6. Two of three TIL cultures grown in IL-2 and 100 U/ml. of IL-6 demonstrated enhanced proliferation as determined by 3H-thymidine uptake. TIL could not be isolated or maintained in vitro when grown in the presence of IL-6 alone without IL-2. IL-6 was also found to enhance the long term non-specific cytotoxicity against an allogeneic nonrenal tumor target. No consistent effect on autologous tumor-specific cytotoxicity was demonstrated. We conclude that IL-6, when used in combination with IL-2, may modestly enhance the long-term growth of RCC-derived TIL.

Human recombinant interleukin-6 enhances antibody-dependent cellular cytotoxicity of human tumor cells mediated by human peripheral blood mononuclear cells

The effects of human recombinant interleukin-6 (hrIL-6) on antibody-dependent cellular cytotoxicity (ADCC) activity mediated by human peripheral blood mononuclear cells (PMNC) were investigated. Human PMNC were preincubated for 24 h with various concentrations of hrIL-6 and were used as effector cells in a 4-h 51Cr-release assay. The ability of hrIL-6 to augment ADCC was measured using anti-colorectal carcinoma mAbs D612, 17.1A and 31.1 (each directed against a distinct tumor antigen) and using three human colorectal carcinoma cell lines, LS-174T, WiDr and HT-29, as targets. A significant increase in ADCC activity was observed after PMNC were preincubated in 100-400 U/ml but not in lower concentrations of hrIL-6. Variations in activities of PMNC among donors were observed. Non-specific mAb showed no effect in augmenting ADCC activity. hrIL-6 treatment did not augment non-specific (non-mAb-mediated) cytotoxicity. The enhancement of ADCC activity was blocked by the addition of an antibody against hrIL-6 but not by an antibody to the IL-2 receptor (capable of blocking the induction of lymphokine-activated killer cell cytotoxicity by IL-2), suggesting that hrIL-6 augmentation of ADCC activity may not be mediated through IL-2. These results demonstrate that hrIL-6 augments ADCC activity of human PMNC using mAbs to human tumor antigens and human tumor cells as targets, suggesting a potential role for IL-6 in combination with anti-cancer antibodies for cancer immunotherapy.

The modulation of interleukin 1 production by interferon gamma, and the inhibitory effects of gold compounds

We have studied the in vitro effects of gold sodium thiomalate (GST) and auranofin (Auf) on the production of interleukin 1 (IL1) expressed as thymocyte co-stimulatory activity (TCSA), and interleukin 1 beta (IL1 beta) as modulated by interferon gamma (IFN gamma). Adherent cells (ADC), of which 80% were monocytes, were obtained from human peripheral blood, and stimulated with lipoprotein polysaccharide (LPS) for 24-48 h. TCSA and IL1 beta production by fresh ADC (0-24 h) was significantly higher than that of aged ADC (24-48 h). The addition of IFN gamma to ADC cultures, however, maintained the capacity of aging ADC to respond optimally to LPS. The addition of GST or Auf inhibited this modulatory effect of IFN gamma, resulting in a marked reduction of TCSA and IL1 beta production. The effects of IFN gamma on the production of IL1 may be important in the pathogenesis of rheumatoid arthritis (RA). The inhibition by GST and Auf of IFN gamma modulation may contribute to the therapeutic efficacy of these drugs in RA.

Interleukin-6: historical background, genetics and biological significance

Interleukin-6 (IL-6) is a pleiotropic cytokine previously known as B cell stimulatory factor (BSF-2), interferon-beta 2 (IFN-beta 2), 26-kDa protein, and hepatocyte stimulating factor (HSF). The name IL-6 was proposed when the nucleotide sequences of the cDNAs for these proteins had been determined and the molecules were found to be identical. IL-6 production can be induced by a wide variety of agents in a wide range of cells, although IL-6 gene expression seems to be regulated in a tissue and stimulus specific manner. At least 3 different signal pathways regulate IL-6 gene expression, emphasizing its multiply inducible nature. The currently known activities of IL-6 include regulatory functions in hematopoiesis, immune reactions and acute phase responses. IL-6 appears to be a key member of the IL family; however, it is still poorly understood how IL-6 interacts with other lymphokines within the network. The anti-viral activity of IL-6 seems to be negligible. Elevated IL-6 levels have been found in diseases like rheumatoid arthritis, multiple myeloma and systemic lupus erythematosus. The abnormal expression and dysregulation of IL-6 in certain disorders may be a typical feature of this cytokine, making it the first cytokine that may be directly related to pathogenesis.