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Biomedical subjects

R Kirnbauer

Publications and source records attributed to R Kirnbauer.

49 records · Page 3Linked to original sources
PubMed1990

Human keratinocytes are a source for tumor necrosis factor alpha: evidence for synthesis and release upon stimulation with endotoxin or ultraviolet light.

Tumor necrosis factor alpha (TNF-alpha), in addition to being cytotoxic for certain tumor cells, has turned out as a multifunctional cytokine that is involved in the regulation of immunity and inflammation. Since human keratinocytes have been demonstrated to be a potent source of various cytokines, it was investigated whether epidermal cells synthesize and release TNF-alpha. Supernatants derived from normal human keratinocytes (HNK) and human epidermoid carcinoma cell lines (KB, A431) were tested both in a TNF-alpha-specific ELISA and a bioassay. In supernatants of untreated epidermal cells, no or minimal TNF-alpha activity was found, while after stimulation with lipopolysaccharide (LPS) or ultraviolet (UV) light, significant amounts were detected. Western blot analysis using an antibody directed against human TNF-alpha revealed a molecular mass of 17 kD for keratinocyte-derived TNF-alpha. These biological and biochemical data were also confirmed by Northern blot analysis revealing mRNA specific for TNF-alpha in LPS- or ultraviolet B (UVB)-treated HNK and KB cells. In addition, increased TNF-alpha levels were detected in the serum obtained from human volunteers 12 and 24 h after a single total body UVB exposure, which caused a severe sunburn reaction. These findings indicate that keratinocytes upon stimulation are able to synthesize and release TNF-alpha, which may gain access to the circulation. Thus, TNF-alpha in concert with other epidermal cell-derived cytokines may mediate local and systemic inflammatory reactions during host defense against injurious events caused by microbial agents or UV irradiation.

Blotting, Northern↗
PubMed1990

Cross-linking Fc receptors on monocytes triggers IL-6 production. Role in anti-CD3-induced T cell activation.

IL-6 is a multifunctional cytokine which is produced by a variety of cells. Therefore it was examined whether anti-CD3-induced T cell activation was associated with the induction of functionally relevant IL-6 in human monocyte accessory cells. Significantly increased amounts of IL-6 were detected in supernatants of anti-CD3-treated PBMC. Stimulation of FACS-sorted greater than 98% pure monocyte accessory cells, but not of highly purified T cells with anti-CD3, resulted in an increased IL-6 production. Furthermore, anti-CD3 significantly enhanced IL-6 mRNA expression in monocyte accessory cells. IL-6 production was not limited to anti-CD3, inasmuch as equivalent IL-6 stimulation could be achieved with a mouse IgG2a isotype control antibody. In contrast to solid phase-bound mouse IgG2a, the soluble form of this antibody failed to induce IL-6 secretion indicating a requirement for Fc gamma RI receptor cross-linking. Moreover, this property may be specific for the Fc gamma RI receptor inasmuch as mouse IgG1 antibodies binding to the Fc gamma RII receptor did not significantly enhance IL-6 production. The role of IL-6 being an additional signal in T cell activation was confirmed by the finding that an anti-IL-6 antiserum was able to suppress anti-CD3-induced T cell activation. These data indicate that binding of anti-CD3 to Fc gamma RI may generate an activation signal towards the monocyte accessory cell leading to the production and secretion of monocyte IL-6, which in turn augments T cell activation, and also may be relevant to a variety of antibody-mediated immune responses against viral and bacterial infections.

Antigen-Presenting Cells↗
PubMed1990

Ultraviolet light induces increased circulating interleukin-6 in humans.

Although the clinical effects of acute exposure to ultraviolet (UV) light--such as cutaneous inflammation, malaise, somnolence, chills and fever--have been appreciated many years, the underlying mechanisms mediating these effects are poorly understood. Interleukin-6 (IL-6) is a potent cytokine with a wide variety of biologic activities, including induction of fever and acute phase response. Because IL-6 is produced by keratinocytes in vivo and in vitro and because the release is enhanced by UV light, the present study was performed to investigate the effect of a single UV dose eliciting moderate to severe sunburn reaction on the production of IL-6 in vivo. Therefore, plasma of UV-treated human subjects was evaluated for IL-6 activity by testing its capacity to induce the proliferation of an IL-6-dependent hybridoma cell line (B9). In contrast to plasma samples obtained before UV exposure, post-UV-specimens contained significant levels of IL-6 peaking at 12 h after UV irradiation. Plasma IL-6 activity was neutralized by an antiserum directed against recombinant human IL-6, and upon HPLC gel filtration exhibited a molecular weight of around 20 kD. Moreover, plasma IL-6 levels correlated remarkably with fever course followed by an increase of acute phase proteins such as C-reactive protein. These data indicate that IL-6, which is released by keratinocytes following UV exposure, may gain access to the circulation and via its pyrogenic as well as acute phase-inducing effect may function as an important mediator of systemic sunburn reaction.

Adult↗
PubMed1990

Epidermal cell-contra-interleukin 1 inhibits human accessory cell function by specifically blocking interleukin 1 activity.

Ultraviolet B (UVB) radiation (280-320 nm) is capable of suppressing selected cell mediated immune responses by inhibiting the function of antigen presenting/accessory cells. Human keratinocytes and carcinoma cell lines (A431) upon UVB radiation or treatment with PMA secrete a suppressor factor, which blocks IL 1 activity (hEC-contra-IL 1). Therefore, the capacity of this UVB-inducible cytokine to modulate human accessory cell function was tested. Human peripheral blood mononuclear cells were stimulated with the mitogenic anti-CD3 monoclonal antibody OKT3 and thymidine incorporation into proliferating T-cells was measured as an index for monocyte accessory cell activity. Addition of hEC-contra-IL 1 which was purified by HPLC chromatography partially decreased OKT3 induced T-cell proliferation in a dose dependent manner. Human EC-contra-IL 1, however, failed to inhibit blastogenesis when T-cells depleted of accessory cells were stimulated in an accessory cell independent fashion via OKT3 attached to the bottom of microtiter plates. Recombinant human (rh) IL 1, but not rhIL 6 was able to reconstitute hEC-contra-IL 1 suppressed blastogenesis in a dose dependent manner. Furthermore, the combined addition of h-EC-contra-IL 1 and an antibody against rhIL 6 to cultures resulted in an additive inhibitory effect which could not be observed when hEC-contra-IL 1 was added together with a monoclonal antibody against rhIL 1 alpha/beta. These studies indicate that hEC-contra-IL 1 is capable of suppressing human accessory cell function by specifically blocking IL 1 activity. This property of hEC-contra-IL 1 points to a novel mechanism by which UVB radiation may modulate human accessory cell function in an indirect manner.

Animals↗
PubMed1990

Ocular symptomatology in familial hypomelanosis Ito. Incontinentia pigmenti achromians.

Hypomelanosis Ito (HI) is a very rare neurocutaneous syndrome which is often associated with cutaneous, cerebral, musculoskeletal and ocular abnormalities. The paper deals with changes in familial HI (mother and daughter) with special consideration of ocular symptomatology; it also presents a review about the relevant literature published to date--not documented with photographs with one exception. The argument is raised whether all ocular changes described in HI actually belong to the syndrome or are partly a mere coincidence. There is also a description of a cataract which has never been observed in cases of HI. Electrophysiological tests (electroretinography, electro-oculography, visual-evoked potential) which to date have not been carried out for HI, are presented and their results reported. Mention is also made of the hereditary factor which has so far been questioned; it is assumed that it is autosomal dominant in character. In this context, the results of a chromosome analysis in both mother and daughter are presented.

Adult↗
PubMed1989

IFN-beta 2/IL-6 augments the activity of human natural killer cells.

MHC nonrestricted cytotoxic cells play an important role in the killing of tumor cells in vitro and potentially in vivo. The activity of these cells is regulated by several cytokines such as IL-2 and IFN. In the present study we provide first evidence that IL-6 significantly augments the cytotoxic activity of human NK cells. IL-6 is produced by many different cells and is also known as IFN-beta 2, B cell stimulatory factor 2, hybridoma growth factor, hepatocyte-stimulating factor, and 26 kDa protein. IL-6 stimulates the activity of human CD3- NK cells but not that of CD3+ non-MHC-restricted cytotoxic T lymphocytes. As is the case with IL-2, the IL-6-mediated augmented cytotoxicity was a result of a more efficient lysis, but was not caused by an increased effector to target cell binding. Moreover, the effect of IL-6 on NK cell activity was blocked by a mAb directed against IL-2, and IL-6 itself was found to be a potent inducer of IL-2 production in cultured human PBMC. Thus it may be concluded that IL-6 enhances the cytotoxic activity of NK cells via IL-2. This newly recognized property of IL-6, which is produced by almost any cell, may be of importance in host defense against microbes and malignancies and therefore could contribute to improve the adoptive immunotherapy by using lymphokine-activated killer cells.

Adjuvants, Immunologic↗
PubMed1989

IFN-beta 2, B cell differentiation factor 2, or hybridoma growth factor (IL-6) is expressed and released by human epidermal cells and epidermoid carcinoma cell lines.

IL-6, which is also known as IFN-beta 2, hybridoma growth factor, hepatocyte-stimulating factor, and B cell differentiation factor, mediates acute phase responses including fever, has lymphocyte-stimulating capacities, and antiviral activity. IL-6 is produced by monocytes, fibroblasts, certain lymphocytes, and various tumor cells. The present study demonstrates that this multifunctional cytokine is released also by normal human epidermal cells (EC) and human epidermoid carcinoma cell lines (A431, KB). Accordingly, supernatants derived from freshly isolated EC, long term keratinocyte cultures, A431, or KB cells stimulated the proliferation of a hybridoma growth factor/IL-6-dependent plasmacytoma cell line (B9). IL-6 constitutively was produced in the presence of serum proteins. The addition of IL-1 alpha, IL-1 beta, or the tumor promoter PMA significantly enhanced the synthesis and release of EC-derived IL-6 (EC-IL 6). Like monocyte or fibroblast-derived IL-6, EC-IL-6 exhibited Mr microheterogeneity within 21 and 28 kDa. Similarly in Western blotting experiments an antiserum directed against human rIFN-beta 2/IL-6 detected the different Mr forms of EC-IL-6. Moreover, this antiserum was able to block the B9 cell growth-promoting capacity of EC-IL-6 strongly suggesting that this EC-derived mediator is closely related, if not identical with IL-6. This was further confirmed by Northern blot analysis detecting IL-6 specific mRNA both in long term cultured keratinocytes and A431 cells by hybridization with a cDNA fragment encoding for B cell differentiating factor 2/IL-6. Therefore, in addition to the production of other cytokines as previously reported, EC and in particular keratinocytes also synthesize and release IL-6. This further supports the important regulatory role of the epidermis during the pathogenesis of inflammatory, autoimmune, and neoplastic diseases.

Animals↗
PubMed1989

Altered production of immuno-modulating cytokines in patients with atopic dermatitis.

Atopic dermatitis (AD) represents an inflammatory skin disorder which is characterized by many signs of immunodeficiency. Particularly, decreased lymphoproliferative responses upon stimulation with mitogens as well as bacterial antigens were reported repeatedly. Since there is increasing evidence for a network of immuno-modulating cytokines playing a crucial role in the regulation of immunity and inflammation, in the present study we investigated whether an altered production of these mediators is one of the pathomechanisms responsible for the altered immune response in AD. For this purpose the 24-h supernatants of LPS- and PHA-stimulated or unstimulated mononuclear cells (MNC) from patients with AD of a moderate to severe disease activity and from nonatopic healthy controls were tested for Interleukin-1 (IL-1) and Interleukin-2 (IL-2) activity. Whereas supernatants of unstimulated MNC of AD patients and controls did not contain significantly different levels of these cytokines, LPS-stimulated MNC of AD patients released significantly less IL-1 in the supernatants. Similarly, the production of IL-2 by PHA-stimulated MNC of AD patients was significantly decreased in comparison to the controls. Moreover, there was a strong correlation between IL-1 and IL-2 levels. These findings indicate that diminished lymphoproliferative responses in AD may partly be caused by a decreased capacity of MNC to release immuno-modulating cytokines, even upon appropriate stimulation.

Dermatitis, Atopic↗
PubMed1988

Detection of a specific inhibitor of interleukin 1 in sera of UVB-treated mice.

It was recently demonstrated that murine keratinocytes upon irradiation with ultraviolet (UV) light release an immunosuppressive cytokine which blocks the biological activity of interleukin 1 (IL 1). This epidermal cell derived inhibitor (EC-contra IL 1) exhibits a molecular weight of 40 kD and a pI of approximately 9.0. EC-contra IL 1 in vivo possibly may penetrate through the basal lamina and subsequently cause systemic immunosuppression following UV-exposure. In the present study, we tested whether EC-contra IL 1 can also be detected in vivo. Serum samples obtained from total body UV-exposed mice were subjected to HPLC gel filtration and tested for IL 1 inhibitory activity. While a non-specific high molecular weight (300 kD) suppressor factor was detected in sera of both UV-exposed and sham treated control mice, a specific IL 1 inhibitor exhibiting a molecular weight of 40 kD was observed only in sera of UV-exposed mice. This cytokine named serum-contra IL 1 was maximally released 24 h after UV-exposure, exhibited a pI of 9.0, and blocked the activity of natural as well as recombinant interleukin 1 in a dose dependent manner. Serum-contra IL 1 did not suppress interleukin 2 or interleukin 3 and did not inhibit spontaneous cell proliferation. The present biochemical and biologic data suggest that serum-contra IL 1 and EC-contra IL 1 appear to be closely related if not identical. These observations therefore indicate that keratinocytes upon UV-irradiation in vivo release EC-contra IL 1 which may at least partly be responsible for the immunosuppression following UV-exposure.

Animals↗
PubMed1988

Keratinocyte-derived interleukin 3.

Interleukin 3 (IL 3) initially was described as a cytokine which is produced by murine T lymphocytes and has multicolony stimulating factor (CSF) activity, activates mast cells and induces the proliferation of hematopoietic stem cell lines. In addition to T cells murine keratinocytes also produce an IL 3-like factor which according to its biological, biochemical and antigenic properties is indistinguishable from murine T cell IL 3. Moreover, by Northern blot analysis murine keratinocytes were found to express mRNA homologous to T cell IL 3 cDNA. Similarly, human keratinocytes have been shown to release an IL 3-like cytokine which also enhances the activity of natural killer cells and stimulates the release of oxygen radicals by granulocytes. However, human IL 3 mRNA could not yet be detected in human epidermal cells or epidermoid carcinoma cell lines. These findings indicate that human keratinocyte IL 3 appears to be distinct from T cell IL 3. Nevertheless, the exact nature of this cytokine remains to be clarified by sequence analysis and gene cloning. Through the production of these cytokines with IL 3-like capacity keratinocytes may participate in the regulation of the activity of different hematopoietic cells and thereby turn on early nonspecific host defense mechanisms against transformed cells and various harmful microbial organisms.

Animals↗