Expression of HLA-DQ antigens on keratinocytes in Borrelia spirochete-induced skin lesions

Cytokine regulation of major histocompatibility complex antigen expression by human oral and skin keratinocytes

The expression, and cytokine modulation, of major histocompatibility complex (MHC) class I and class II molecules on oral and skin keratinocytes were compared in cell culture. Both cell types expressed class I, but not class II, constitutively. However, stimulation with interferon-gamma, but not interleukin-1 alpha, and -1 beta, tumour necrosis factor-alpha or lymphotoxin, induced increased expression of class I and de-novo expression of HLA-DR on both cell types. Oral keratinocytes differed from skin keratinocytes in that they exhibited greater sensitivity to interferon-gamma stimulation and higher stimulated expression of both class I and HLA-DR. In addition, interferon-gamma stimulated oral, but not skin, keratinocytes to express HLA-DP and -DQ. These observations suggest that, like skin keratinocytes, under certain conditions, oral keratinocytes may be able to act as antigen-presenting cells. This may be important in the initiation and progression of some immune-mediated mucocutaneous diseases. Moreover, differences in MHC expression may help to explain differences in the presentation of these diseases on the skin and oral mucosa.

The expression of MHC class II (Ia) antigens on mouse keratinocytes following epicutaneous application of contact sensitizers and irritants

The expression of MHC class II (Ia) antigens on mouse keratinocytes was studied following both the induction and elicitation of contact sensitivity, and after primary irritant reactions. IA+ and IE+ keratinocytes were detected, using an indirect immunofluorescence assay on epidermal sheets, only after the induction and elicitation of contact sensitivity with the sensitizers oxazalone, picryl chloride and 2,4-dinitrochlorobenzene but not with formaldehyde. Ia+ keratinocytes were not detected after epicutaneous application of the non-sensitizing irritants croton oil, SDS and anthralin, or following attempted sensitization of nude mice, suggesting that the expression of Ia antigen on keratinocytes during contact sensitivity reactions is T-cell mediated. Because Ia antigen expression on keratinocytes could be detected only several days after induction or elicitation of contact sensitivity, and contact sensitization could also be demonstrated to occur independently of aberrant Ia expression, Ia+ keratinocytes cannot be involved in the initiation of these reactions. However, they might be important in exerting an immunomodulatory influence during the later stages of the responses to certain sensitizers.

Induction of mRNA for HLA-DR beta in human keratinocytes cocultured with interferon-gamma

Explanted human keratinocytes exposed in vitro to recombinant interferon-gamma (IFN-gamma) were investigated for the appearance of mRNA for HLA-DR. Using in situ hybridization with a (35S)UTP-labelled HLA-DR beta cRNA probe, mRNA-positive cells were detected already within 6 h with maximal numbers of positive cells as well as the amount of mRNA per cell after 48 h. The corresponding protein HLA-DR, as analysed by immunoperoxidase staining, was detected on 20%-40% of the cells after 24 h and on almost all cells within 48 h. The expression of HLA-DQ and -DP antigens were always exceeded by that of HLA-DR. Whereas an increase in the concentration of IFN-gamma above 50 U/ml did not affect the maximal level of HLA-DR reactive cells, there was a fourfold increase in the frequency of cells reactive with HLA-DQ and a twofold increase for HLA-DP when the IFN-gamma concentration was raised from 50 to 500 U/ml. When IFN-gamma was withdrawn from the cultures, HLA-DR mRNA and protein synthesis ceased--indicating the continuous need for IFN-gamma to maintain the HLA-DR synthesis in keratinocytes.

Phenotypic characterization of mononuclear cells and class II antigen expression in angular cheilitis infected by Candida albicans or Staphylococcus aureus

In the present study we characterized the phenotypes of infiltrating mononuclear cells in angular cheilitis lesions to further explore the pathogenesis of this disorder. Frozen sections from lesions infected by Candida albicans and/or Staphylococcus aureus were subjected to immunohistochemical analysis utilizing monoclonal antibodies directed to subsets of T-lymphocytes, B-lymphocytes, and macrophages. In addition, the expression of Class II antigens (HLA-DP, -DQ, -DR), the interleukin 2- and transferrin-receptors was studied on resident and infiltrating cells. An intense infiltration of T-lymphocytes was accompanied by expression of Class II antigens on the epidermal keratinocytes in lesion infected by Candida albicans. The Staphylococcus aureus infected lesions displayed a diffuse infiltration of T-lymphocytes but virtually no expression of Class II antigen by epidermal keratinocytes. These observations suggest that the cell-mediated arm of the immune system is involved in the inflammatory reaction of lesions infected by Candida albicans. In addition, the present study confirms that epidermal expression of Class II antigens is closely related to the type and magnitude of the infiltrating T-lymphocyte. Finally, these findings indicate that the type of inflammatory reaction in angular cheilitis is primarily dependent on the isolated microorganism, although the clinical pictures of the disorder are virtually identical.

Differential expression of major histocompatibility complex class II antigens on human keratinocytes

Skin biopsies from 136 patients with 30 different dermatoses and eight biopsies of normal skin were investigated with the avidin-biotin-peroxidase complex method with regard to the expression of major histocompatibility complex class II antigens human leukocyte antigen (HLA) HLA-DR, HLA-DQ, HLA-DP on keratinocytes. In normal skin the expression of these antigens was restricted to acrosyringia and Langerhans cells. In the dermatoses investigated HLA-DR was found in 51.5% (70 of 136), HLA-DQ in 24.3% (33 of 136), and HLA-DP in 20.5% (8 of 39). In 37 cases (27.2%) only HLA-DR could be detected, whereas in 33 cases (24.3%) HLA-DR was expressed jointly with HLA-DQ. Coexpression of HLA-DR and HLA-DQ was found especially often in cutaneous T cell lymphomas, skin tumors, and inflammatory dermatoses.

Laboratory aspects of Lyme borreliosis

Lyme borreliosis (Lyme disease), a common tick-borne disorder of people and domestic animals in North America and Europe, is caused by the spirochete Borrelia burgdorferi. Following the discovery and initial propagation of this agent in 1981 came revelations that other tick-associated infectious disorders are but different forms of Lyme borreliosis. A challenge for the clinician and microbiology laboratory is confirmation that a skin rash, a chronic meningitis, an episode of myocarditis, or an arthritic joint is the consequence of B. burgdorferi infection. The diagnosis of Lyme borreliosis may be established by (i) directly observing the spirochete in host fluid or tissue, (ii) recovering the etiologic spirochete from the patient in culture medium or indirectly through inoculation of laboratory animals, or (iii) carrying out serologic tests with the patient's serum or cerebrospinal fluid. The last method, while lacking in discriminatory power, is the most efficacious diagnostic assay for most laboratories at present.

Products of class II major histocompatibility complex gene subregions are differentially expressed on keratinocytes in cutaneous diseases

Aberrant expression of class II major histocompatibility complex (MHC) subregion antigens by keratinocytes was examined immunohistochemically in a range of cutaneous disorders. Although cell surface expression of human lymphocyte antigen (HLA)-DR was observed, HLA-DQ and HLA-DP were not expressed in any disorder investigated except for allergic contact dermatitis. Epidermal Langerhans cells expressed antigens of all three subregions on the cell surface. Differential expression of class II MHC subregion antigens may be related to tissue levels of gamma-interferon or to different functions of each subregion.

Recombinant gamma interferon and in vivo induction of HLA-DR antigens

Recombinant human IFN-gamma, used for treatment of melanoma and renal carcinoma, was found to induce HLA-DR expression on human keratinocytes in vivo. HLA-DR antigens bound to keratinocytes of the basal and suprabasal layers of the epidermis were observed after intramuscular or intravenous injections of 0.5 mg/kg body weight IFN-gamma, 3 times a week. Keratinocyte-bound HLA-DR antigens were first observed at the beginning of the third or fourth week of treatment, but HLA-DQ and HLA-DP antigens were never detected on keratinocytes. The intracytoplasmic constant (gamma) chain of the class II molecules was also not detectable within the keratinocytes. Patients who received IFN-alpha 2 therapy, did not exhibit keratinocyte-bound HLA-DR antigens.

A simple in vitro technique for studies on induction of class II transplantation antigens on keratinocytes

A new technique is described for evaluation of the induction and kinetics of class II transplantation antigens on keratinocytes. By culturing small rat or human skin specimens for 2-5 days in media containing gamma-interferon, class II antigens were detected on keratinocytes by immunohistochemistry. This technique is rapid and technically simple compared to keratinocyte cultures and raises the possibility of studying other cells in the skin.

Amplification of T-cell response to PPD by epidermal cell suspensions containing HLA-DR-expressing keratinocytes

The biological importance of the presence of class II transplantation antigens on highly differentiated epithelial cells such as keratinocytes in certain conditions, is still unknown. We have therefore investigated the antigen-presenting capacity of separated human epidermal cells obtained from tuberculin-reactive skin 6 days after intradermal injection of purified protein derivative (PPD). Earlier studies have shown a high percentage of HLA-DR-expressing keratinocytes at this time. Peripheral adherent blood cells were used as control stimulator cells and highly purified peripheral blood T lymphocytes as responder cells. The T-cell proliferation in response to PPD in the presence of autologous epidermal cells from normal and tuberculin-reactive skin was measured by [3H]thymidine incorporation on day 6. The latter cell population, 76-86% of which consisted of HLA-DR-expressing cells as judged by immunocytochemistry, induced a greater T-cell response to PPD than do normal epidermal cells. This discrepancy in the T-cell proliferation could not be explained by a difference in the numbers of anti-Leu 6 or anti-HLA-DQ-reactive Langerhans cells. The present data indicate that epidermal cell suspensions containing HLA-DR-expressing keratinocytes induce a greater T-cell response to PPD than do normal epidermal cells.

In vivo induction of Ia antigens on rat keratinocytes by gamma-interferon

Recombinant rat IFN-gamma was found to induce Ia antigen expression on rat keratinocytes in vivo. Strong expression of Ia antigen on keratinocytes of rat ears was produced after intradermal injections of 10,000 U IFN-gamma once daily on 3 successive days. The expression was still pronounced 2 days after the last injection, but had disappeared 4 days later.

Expression of HLA-DR molecules by keratinocytes, and presence of Langerhans cells in the dermal infiltrate of active psoriatic plaques

Immunoperoxidase staining of skin sections and immunofluorescence analysis of keratinocyte suspensions obtained from suction blisters of psoriatic plaques were performed using an mAb, Josh 524.4.1, and Fab'2 fragments of a rabbit antiserum, both of which are directed against nonpolymorphic determinants of HLA-DR molecules. HLA-DR+ keratinocytes were present in plaques, but not normal-appearing skin, from a significant portion of patients with active psoriasis. Double-labelling immunofluorescence experiments with either the monoclonal or polyclonal anti-HLA-DR antibody, in conjunction with the mAb OKT6, which identifies DR+ Langerhans cells, demonstrated that HLA-DR molecules were present on OKT6- keratinocytes. The dermal infiltrate of psoriatic plaques contained T cells expressing the activation antigens, IL-2 receptor (Tac) and HLA-DR, as well as macrophages and OKT6+ cells. There was little difference in the characteristics of the dermal infiltrate between the lesions with or without HLA-DR+ keratinocytes. OKT6+ presumptive Langerhans cells were also found in the dermal infiltrates of patients with lichen planus, contact dermatitis, spongiotic dermatitis, erythema multiforme, basal and squamous cell carcinoma. Studies of keratinocyte suspensions showed that 7-84% of keratinocytes were HLA-DR+. Flow cytometry experiments showed that keratinocytes at all stages of differentiation were HLA-DR+. However, the stem cell-enriched population contained the highest proportion of HLA-DR+ cells. HLA-DR expression by keratinocytes correlated with disease activity. The expression was reversible with successful medical therapy. HLA-DR+ keratinocytes may activate T cells directly or may present an as yet unknown antigen to T cells. These studies provide further support for the hypothesis that immunological mechanisms play an important role in the pathogenesis of psoriasis.