Purification of human interleukin 1 by high-performance liquid chromatography

Production of natural killer cell activity-augmenting factor (interleukin-6) by human epiphyseal chondrocytes

OBJECTIVE

We sought to determine the capacity of human epiphyseal chondrocytes to modulate the cytotoxic activity of human natural killer (NK) cells by determining whether they release interleukin-6 (IL-6), a cytokine recently shown to stimulate NK cell activity.

METHODS

Conditioned medium from human epiphyseal chondrocyte cultures (Ch-CM) was tested for IL-6 activity using the B9 cell hybridoma assay. Its NK cell-stimulating capacity in the presence of K562 (myelogenous leukemia) cells or human chondrocytes was evaluated in a 4-hour 51Cr-release assay. Ch-CM-derived IL-6/NK cell-augmenting factor activity was partially purified by high-performance liquid chromatography (HPLC) gel filtration and Western blot.

RESULTS

Ch-CM contained an NK cell-augmenting factor (NKAF) which was blocked by IL-2 or IL-6 antibodies. Ch-CM did not contain detectable IL-2 activity, but it stimulated IL-2 production by human peripheral blood lymphocytes (PBL). This IL-2-inducing capacity was inhibited by IL-6 antibodies, indicating that chondrocytes release an IL-6-like activity. Ch-CM significantly enhanced the proliferation of IL-6-dependent B9 hybridoma cells, and Western blot analysis of Ch-CM revealed specific bands corresponding to those of highly purified IL-6. Upon HPLC gel filtration, chondrocyte NKAF copurified with chondrocyte IL-6. Pure IL-6 and chondrocyte IL-6 were tested for their ability to stimulate the cytotoxic activity of human PBL against chondrocytes. Both mediators significantly enhanced chondrocyte killing. Lysis of chondrocytes by PBL was mediated by NK cells, since depletion of CD16+ cells resulted in inhibition of the activity.

CONCLUSION

Thus, upon stimulation, chondrocytes produce IL-6 which, through IL-2 induction, augments the activity of NK cells against K562 target cells as well as against chondrocytes.

Constitutive release of IL6 by human papillomavirus type 16 (HPV16)-harboring keratinocytes: a mechanism augmenting the NK-cell-mediated lysis of HPV-bearing neoplastic cells

In the present study we demonstrate that the cultured human keratinocyte cell line (SK-v cells) harboring and expressing integrated human papillomavirus type 16 (HPV16) DNA sequences constitutively releases IL6, which is known as a pleiotropic immunoregulatory cytokine of potential antitumor properties. The presence of IL6 activity in SK-v cell-conditioned media (SK-v CM) was demonstrated by tritiated thymidine incorporation into IL6-dependent B9 murine plasmacytoma cells. The effect on B9 cells was specific since it could be inhibited by anti-IL6 neutralizing antibodies but not by a normal control serum. IL6 did not affect SK-v cell growth; however, it significantly augmented NK cell activity of human peripheral blood lymphocytes against both K562 erytholeukemic and SK-v cells as assessed by 51Cr release assay. SK-v CM displayed NK cell-augmenting activity that copurified with IL6 activity in both size exclusion and anion-exchange HPLC. Furthermore, SK-v cell-derived NK cell stimulatory activity could be neutralized with anti-IL6 antibodies. These results suggest that HPV-harboring neoplastic cells can release IL6 which may indirectly mediate tumor death by augmentation of NK cell activity.

Purification of human placental trophoblast interferon by two-dimensional high performance liquid chromatography

Human placental trophoblast challenged with Sendai virus induced IFNs mainly of the beta-type (75%) and relatively low levels of the alpha-type (25%). A two-step high performance liquid chromatographic procedure ("two-dimensional HPLC") has been developed for the complete purification of the placental trophoblast interferon beta (tro-IFN-beta) from serum-containing culture supernatant. The method involved a combination of high performance liquid affinity chromatography (HPLAC) on Cibacron Blue 3GA immobilized on an activated pressure stable macroporous synthetic polymer, 2-hydroxyethyl methacrylate vinyl sulphone (HEMA-BIO 1000 VS), as the first dimension and reversed-phase high performance liquid chromatography (RP-HPLC) on Separon SGX C-18 as the second. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblot experiments showed that the tro-IFN-beta was present as a 24 kDa protein. Densitometric scanning analysis of Coomassie-stained gel revealed the purity of the final preparation to be greater than 99%. The purified tro-IFN-beta had a specific activity of 1.03 x 10(8) IU/mg of protein and the overall recovery was 81% of the total IFN-beta activity in the crude preparation and 61% of the total IFN activity.

Partial purification and characterization of a factor produced by mitogen-stimulated sheep mononuclear cells with thymocyte-activating and cartilage-degrading properties

Ovine peripheral blood mononuclear cells stimulated with concanavalin A released a soluble factor capable of inducing cartilage resorption and thymocyte activation in vitro, but not lysis of the murine L929 cell line. The active moiety has a molecular mass of around 15-20 kDa on gel filtration columns, and can be separated into two molecular species with isoelectric points of 6.3 and 4.6 respectively. These two species were partially purified by gel filtration, chromatofocusing, high performance liquid chromatography on hydroxylapatite and anion exchange columns, and SDS-polyacrylamide gel electrophoresis. Both partially purified species showed a major band on gels at 16 kDa. When the band from the acidic factor was excised and eluted from gels it was found to retain some cartilage-degrading and thymocyte-activating properties. The biochemical and biological characteristics of the two factors is consistent with their being members of the interleukin-1 family of cytokines.

Separation of proteins by reversed-phase high-performance liquid chromatography. I. Optimizing the column

In the process of developing a new analytical technology (the chromatophoresis process) which couples reversed-phase high-performance liquid chromatography (HPLC) to sodium dodecyl sulfate polyacrylamide gel electrophoresis in a real-time automated system, it was apparent that improvements in resolving power for the first-dimension (HPLC) separation were necessary. The present paper describes the optimization of the column for our initial work on reversed-phase HPLC separations. Polymeric (polystyrene) packings having particle diameters of 5 micron and pore diameters of 300 A were generally superior in terms of resolution, sample recovery and minimization of "ghosting". Optimum column dimensions were 50 x 1.0 mm I.D. for the flow-rates required in our system (10-100 microliter/min).

Fever and increased serum IL-1 activity as a systemic manifestation of acute phototoxicity in New Zealand White rabbits

Ultraviolet (UV) radiation is a significant environmental hazard for humans and animals. Although the clinical effect of an acute UV exposure such as cutaneous inflammation, malaise, somnolence, chills, and fever have been appreciated for many years, the underlying mechanisms mediating these effects are poorly understood. Since chills and fever are the most dramatic systemic sequelae after a prolonged exposure to UV, we specifically examined the effect of whole-body UV irradiation on core body temperature and serum endogenous pyrogen activity of New Zealand White rabbits, correlating this with serum interleukin 1 (IL-1) activity and alterations of serum divalent cation levels. We found that an acute dose of UV irradiation (Westinghouse FS-40 lamps, 0.2 mJ/cm2/s X 8 h) resulted in a significant increase in the core body temperature 2 h post UV (0.8 degree C), peaking 5 h post UV (1.8 degree C), and returning to normal 24 h post UV. Likewise, the sera from the UV-irradiated rabbits had significant endogenous pyrogen activity when transferred into naive recipient animals, causing an increase in core body temperature within 45 min (0.65 +/- 0.12 degree C), decreasing over the next 2 h, and returning to normal 6 h post injection. No endotoxin contamination was detected in any serum samples. This post-UV febrile response was accompanied by a prolonged increase in serum IL-1 activity (5-10 X) and a significant alteration in serum divalent cation levels, with the rabbits becoming euthermic even as the serum IL-1 levels remained elevated. These findings provide new information concerning the pathogenesis and kinetics of these systemic effects after an acute dose of UV irradiation.

Blood-membrane interaction in hemodialysis leads to increased cytokine production

Recently much interest has been focused on the role of immunoregulatory cytokines such as interleukin 1 (IL 1) and interleukin 2 (IL 2) during the pathogenesis of immunological as well as inflammatory diseases. Therefore peripheral blood mononuclear cells (PBMC) of eight patients undergoing hemodialysis (HD) were tested for IL 1 and IL 2 production. Before starting HD, cytokine production by PBMC in culture was not altered in comparison to normal healthy controls, however, a significant increase of IL 1 and IL 2 production was observed within the first HD hour which lasted throughout the end of HD. Moreover direct effects of cellulose membranes on PBMC cytokine production as well as serum IL 1 levels have been investigated. Serum IL 1 levels were already elevated before onset of HD and increased further during HD. The discrepancy between PBMC IL 1 production and serum IL 1 levels may be due to the diminished excretion in patients with end-stage renal disease. Since addition of dialysis membrane particles enhanced monocytes to produce more IL 1 as well as lymphocytes to release more IL 2, a direct stimulatory membrane effect is postulated. The increased release of immunoregulatory cytokines may account for some of the pathologic findings observed during hemodialysis.

Human keratinocytes and epidermoid carcinoma cell lines produce a cytokine with interleukin 3-like activity

Keratinocytes are capable of releasing distinct immunomodulating cytokines such as epidermal cell-derived thymocyte activating factor (ETAF) and an epidermal cell-derived natural killer cell augmenting factor (ENKAF). The present study was performed to determine whether human keratinocytes also may secrete an interleukin 3 (IL-3)-like mediator and thereby participate in the regulation of mast cell activity in the skin. Supernatants of freshly isolated human epidermal cells (EC) and malignant keratinocyte cell lines (A 431, SCC) were tested for their capacity to induce the proliferation of IL-3-dependent cell lines 32 DCL and FDCP. Human epidermal cell interleukin 3 (EC IL-3) is spontaneously released by freshly isolated EC, A 431, and squamous cell carcinoma (SCC) cells. However, both normal EC and A 431 cells produced increased levels of EC IL-3 activity when cultured in the presence of different stimulants, such as phorbol myristate acetate and lipopolysaccharide. The EC IL-3 activity was not inhibited when treated with a monoclonal anti-IL-1 or anti-IL-2-antibody. Biochemical characterization showed that human EC IL-3 has a molecular weight of 17K, elutes of DEAE-ion exchange high-performance liquid chromatography (HPLC) as one major peak at 0.36 M NaCl, and upon HPLC-chromatofocusing exhibits 3 isoelectric points of 7.8, 7.5, and 5.6. Upon reversed-phase HPLC, EC IL-3 activity eluted at about 100% acetonitrile. When highly purified EC IL-3 was labeled with 125I and subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis, a single homogeneous band exhibiting a molecular weight of 17K was seen, which correlated with the IL-3 activity and was free of ETAF/IL-1, IL-2, and interferon activity. These data indicate that human EC synthesize an IL-3-like cytokine which is distinct from ETAF/IL-1, IL-2, and interferon and thereby may participate in the regulation of mast cell activity during inflammatory and fibrotic, as well as hypersensitivity reactions.

A novel interleukin stimulating free radical production by granulocytes

Polymorphonuclear granulocytes (PMN) are potent producers of free oxygen-derived radicals. Since other granulocyte functions are affected by interleukins, we investigated whether free-radical production can be initiated by a similar mediator. For estimation of free radical production, SOD-inhibitable lucigenin-dependent chemiluminescence and SOD-inhibitable cytochrome C reduction were used. As a source of interleukins, serum-free 24 h culture supernatants of human mononuclear cells (MNC) stimulated with bacterial lipopolysaccharide were prepared. Addition of such supernatants to PMN caused stimulation of sod-inhibitable chemiluminescence and superoxide production. Studies with separated MNC showed that monocytes were the cellular source of the activity. Biochemically, this activity of the supernatants was due to a heat-labile glycoprotein with a MW of approx. 60 KDa. This mediator, termed granulocyte chemiluminescence inducer (GCI), appears to be distinct from interleukin 1 (alpha and beta) and interferon (alpha and gamma). In conclusion we describe a novel monokine, granulocyte chemiluminescence inducer (GCI), which initiates granulocyte free radical production. This interaction of monocytes and granulocytes may also in vivo constitute a new and potent pathway leading to stimulation of free oxygen production by granulocytes.

Monoclonal anti-IL 1 is directed against a common site of human IL 1 alpha and IL 1 beta

Cytokines exhibiting interleukin 1 (IL 1) activity are known as important mediators of immunity and inflammation. Therefore, the ability of a monoclonal anti-IL 1 antibody to neutralize and bind IL 1 was investigated. Anti-IL 1 IgG blocked the IL 1-mediated thymocyte and fibroblast proliferation and also inhibited the biological activity of epidermal cell-derived thymocyte activating factor (ETAF), but did not affect interleukin 2 (IL 2) and interleukin 3 (IL 3) activity. Monoclonal anti-IL 1 blocked the activity and bound to both human IL 1 alpha and IL 1 beta. Additionally using anti-IL 1, it was possible to immunoprecipitate 31 kD, 17 kD and 4 kD biosynthetically radiolabeled biologically active species of IL 1. These data indicate that IL 1 alpha and IL 1 beta share a common site which is responsible for the biological activity. Moreover, this part of the IL 1 molecule also appears to be located within the low mw 4 kD break-down product. Since anti-IL 1 also was capable to detect surface bound IL 1 on LPS-stimulated mononuclear adherent cells, the antibody may help to elucidate the role of surface IL 1 during an immune response. In addition, anti-IL 1 IgG may be very helpful to investigate the in vivo role of IL 1 during the pathogenesis of inflammatory diseases.

Inhibition of the induction of contact hypersensitivity by a UV-mediated epidermal cytokine

UVB exposure (290-320 nm) of mice has been shown to cause systemic suppression of contact hypersensitivity (CHS). Because UVB radiation hardly penetrates the epidermis, epidermal cells have been anticipated to be the site of the initiation of immunosuppression. Supernatants derived from UV-irradiated BALB/c epidermal cell cultures and a keratinocyte cell line (Pam 212) were evaluated for the ability to induce suppression of CHS after i.v. injection to BALB/c mice. Injection of supernatants derived from UV-treated epidermal cells and Pam 212 cells significantly blocked induction but not elicitation of CHS. In contrast, i.v. application of supernatants derived from unirradiated cells did not inhibit CHS. Using high-performance liquid chromatography gel filtration this mediator was shown to be a low-molecular-weight protein (15-50 kD). Moreover UV-mediated inhibitor production seems to be confined to epidermal cells since neither P 388 macrophages nor L 929 fibroblasts released this inhibitory cytokine. Therefore UV radiation may induce epidermal cells to produce an inhibitor of CHS which is distinct from prostaglandins and leukotrienes and may participate in the regulation of UV-mediated local as well as systemic immunosuppression.

Purification to homogeneity and amino acid sequence analysis of two anionic species of human interleukin 1

Two anionic species of human IL-1 have been purified to homogeneity. These molecules were characterized as having pI of 5.4 and 5.2 and molecular weights identical to IL-1/6.8 (17,500). The specific activities of IL-1/5.4 and IL-1/5.2, as measured in the mouse thymocyte co-mitogenic assay, were identical to that of IL-1/6.8, namely 1.2 X 10(7) U/mg, with half-maximal stimulation observed at 2 X 10(-11) M. IL-1/5.4 and IL-1/5.2 were found to be antigenically distinct from IL-1/6.8 in an ELISA. IL-1/5.4 was structurally distinct from IL-1/6.8 based on reverse-phase HPLC or CNBr peptides. Intact IL-1/5.2 and three intact CNBr peptides of IL-1/5.4 were sequenced, with the identification of 74 amino acid residues. These sequences were found to correspond exactly with the amino acid sequence deduced from the IL-1-alpha cDNA reported by March et al.

Granulocyte-activating mediators (GRAM): I. Generation by lipopolysaccharide-stimulated mononuclear cells

We undertook a study to determine whether cytokines exist which are responsible for the activation of polymorphonuclear neutrophilic granulocytes (PMN) besides the already well-known stimuli. Lucigenin-dependent chemiluminescence was used to measure human PMN activation. Addition of supernatants from mononuclear cells stimulated with bacterial lipopolysaccharide produced a long-lasting activation of granulocytes. Induction of chemiluminescence was dose-dependent and inhibitable by superoxide dismutase. Fractionation of mononuclear cells by adherence to plastic dishes or counterflow elutriation proved that monocytes were able to generate granulocyte-activating mediators (GRAM). Production of GRAM was dependent on the dose of the stimulus and appeared to be maximal after 24 h of incubation. Addition of cycloheximide resulted in significantly decreased release of GRAM. Partial characterization of the activity showed GRAM to be heat-labile and sensitive to trypsin, indicating a protein nature of GRAM. The activity fractionated into 2 distinct peaks, one corresponding to 60 kD and another below 10 kD. The interleukin 1 activity did not appear to co-fractionate with GRAM. Evidence presented suggests that the activity corresponds to factors unlikely to have been described previously.

Characterization of a monoclonal antibody directed against the biologically active site of human interleukin 1

Human IL-1 was successfully used to produce an anti-IL-1 mAb. Anti-IL-1 (IgG2a) blocked IL-1-mediated thymocyte and fibroblast proliferation, but did not interfere with the biological effects of other lymphokines, such as IL-2 or IL-3. The antibody immunoprecipitated biosynthetically radiolabeled 33, 17, and 4 kD IL-1. An immunoadsorbent column yielded 20% of initial activity, and upon HPLC size-exclusion chromatography, affinity-purified IL-1 had a molecular mass of approximately 4 kD. These results provide first evidence of a monoclonal anti-IL-1 that reacts with different species of IL-1 and apparently binds to an epitope close to the active site of IL-1. Thus, anti-IL-1 IgG may be very helpful for further investigations of the molecular as well as biological characteristics of IL-1 and related mediators.

Characterization of immunoregulatory cytokines produced by epidermal cells

The epidermis has been identified as an important site for the initiation of immunological events. In addition to the macrophage-like Langerhans cells, keratinocytes within the epidermal cells have been shown to act as immunoregulatory cells through the secretion of cytokines such as epidermal cell-derived thymocyte-activating factor (ETAF) and interleukin 3. Epidermal cell-derived interleukin 3 (EC IL-3), like lymphocyte-derived IL-3, induced the proliferation of IL-3-dependent mast cell-like cell lines. Biochemically, EC IL-3 was a heat-stable protein with a molecular weight of approximately 30 kD. Upon chromatofocusing, EC IL-3 exhibited three isoelectric points, at pI 7.8, 7.4, and 7.1. Furthermore, an antiserum against IL-3 neutralized EC IL-3 activity, suggesting that the molecules are closely related and share similar epitopes. ETAF-like macrophage-derived interleukin 1 (IL-1) is a low molecular weight protein with a multiplicity of amplifying effects on immunological and inflammatory reactions. Thus BALB/c mice were immunized with partially purified IL-1, and immune spleen cells were hybridized with plasmocytoma cells. Supernatants of the hybridoma cultures were screened for their capacity to inhibit IL-1-induced thymocyte proliferation. After expansion and cloning, one clone was selected for ascitic antibody production. The monoclonal anti-IL-1 antibody inhibited both the IL-1-dependent thymocyte and the fibroblast proliferation. Furthermore, the antibody blocked murine and human ETAF activity, suggesting that ETAF and IL-1 share antigenically similar domains. Moreover, by using the monoclonal antibody bound to Staphylococcus aureus cells, it was possible to immunoprecipitate IL-1. In contrast, anti-IL-1 antibody did not inhibit IL-2 or IL-3 activity. These findings demonstrate that the production of immunoregulatory cytokines is not confined to cells of the immune system and that keratinocytes through the production of ETAF and EC IL-3 may mediate inflammatory and hypersensitivity reactions. Furthermore, the monoclonal anti-IL-1 antibody may provide a useful tool for the development of new immunoassays to detect IL-1/ETAF and thereby facilitate the investigation of the role of these cytokines during the pathogenesis of inflammatory diseases.