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

Contact allergy to gold sodium thiosulfate

278 consecutive patients with suspected contact dermatitis were patch tested with the European standard series and gold sodium thiosulfate (0.5% pet.): 13 patients (4.6%) had a positive allergic response to gold sodium thiosulfate (GST). All of these patients were female, with a mean age of 37 years. The most frequent site of eczema in these patients was the head and neck (62%). A seborrhoeic distribution of eczema was common. 46% had involvement of the limbs, 15% had a perianal or perivulval rash. The mean duration of eczema in this group of patients was 15.8 months. 54% of patients allergic to gold were also allergic to nickel. Biopsy of positive patch test reactions to GST were consistent with allergic contact dermatitis.

Expression of class II major histocompatibility antigens by keratinocytes in cutaneous T cell lymphoma

BACKGROUND

Expression of various class II MHC antigens by lesional keratinocytes may play an important role in the pathophysiology of a wide variety of human dermatoses including cutaneous T cell lymphoma (CTCL). Nevertheless, there is relatively little information available concerning the concurrent expression of HLA-DR, -DP, and -DQ class II MHC antigens in CTCL. Therefore, our aim in this study was to determine the prevalence, localization, extent, temporal sequence, and consistency of class II MHC antigen expression by lesional keratinocytes in CTCL.

METHODS

We used a semiquantitative immunohistologic analysis to analyze HLA-DR, -DP, and -DQ expression by lesional keratinocytes in 66 skin biopsies obtained from 39 patients with CTCL.

RESULTS

Class II MHC antigen expression by keratinocytes was observed in 77% of cases. Expression was detected on the cytoplasmic membrane and within the cytoplasm. It varied among cases from focal to confluent. There was a hierarchy of antigen expression in terms of both extent and time course. HLA-DR was expressed first and most extensively, followed by HLA-DP and then HLA-DQ. Comparative studies of multiple serial or concurrent active lesions from 13 cases indicated that the overall pattern and extent of antigen expression was relatively constant within individual patients.

CONCLUSIONS

There was no apparent correlation between class II MHC antigen expression and the clinical stage of disease, the type of CTCL skin lesion, or the overall density of the lesional T cell infiltrate. The hierarchy of keratinocyte class II MHC antigen expression observed in this study paralleled that noted in earlier studies of cultured keratinocytes exposed to recombinant interferon-gamma in vitro. This suggests that lesional cytokine levels may be the critical factor governing class II MHC antigen expression by lesional keratinocytes in CTCL.

Regression in basal cell carcinoma: an immunohistochemical analysis

Spontaneous regression of some cutaneous tumours is well recognized, and is thought to result from an immunological response to the tumour. Regression has previously been noted in basal cell carcinomas, but no studies defining the role of the immune response in the regression of this malignancy have been performed. We have examined 45 primary basal cell carcinomas (BCCs) (20 nodular, 25 superficial) and identified the cellular phenotypes and activation states of the cells infiltrating primary regressing and non-regressing BCCs, by immunocytochemistry. We have found a significantly increased number of CD3+ and CD4+ T cells infiltrating regressing compared with non-regressing tumours, and the expression of interleukin-2 receptor (an early activation marker for T cells) was also increased. There were no significant differences in class II major histocompatibility complex (MHC), CD1, or macrophage antigen expression in these groups. These findings suggest that activated CD4+ cytokine-secreting cells are important in the regression of BCCs.

Antigenic profile of human acrosyringium

The demonstration of HLA-DR on human acrosyringium has led to the suggestion that eccrine epithelium, through its interaction with certain molecules, might play an active role in epidermal immune responses. An immunohistochemical study was undertaken to identify the antigenic profile of acrosyringium in normal skin and following the intradermal administration of a T-lymphocyte-derived cytokine, interferon gamma (IFN-gamma). Acrosyringium in normal skin, in contrast to interappendageal epidermis, was found to lack CD1a+ Langerhans cells. However, antigens CD36 (OKM5) and L1 (MAC387) were uniquely expressed by keratinocytes immediately adjacent to the distal portion of acrosyringium. Constitutive expression of each class II MHC antigen, namely HLA-DR, DP and DQ was observed on luminal acrosyringial cells. EMB11 antigen (CD68), a mononuclear cell determinant, was similarly expressed on acrosyringial epithelium in normal skin. Following intradermal administration of IFN-gamma, intercellular adhesion molecule-1 (ICAM-1) (CD54) was induced on acrosyringial epithelium and the expression of HLA-DR was intensified. A range of other markers including CD3, CD4, CD8, CD11a, CD11b and CD15 were not expressed by acrosyringium either in normal skin or after administration of IFN-gamma. Expression of antigens associated with cell-mediated immune mechanisms on acrosyringium is consistent with the hypothesis that it may have an immunological role in epidermal immune responses.

Immunocytochemical analysis of the cellular infiltrate in primary regressing and non-regressing malignant melanoma

Spontaneous regression occurs in a small proportion of malignant melanomas, and it is important to understand the processes involved in its induction as this may give a guide to future therapies for this disease. We have examined 36 primary malignant melanomas (19 regressing, 17 non-regressing) and identified the cellular phenotypes and activation states of the cells infiltrating regressing and non-regressing primary melanomas by immunochemistry. We have found a significantly increased number of CD3-positive cells and an increased ratio of CD4/CD8-positive cells infiltrating regressing compared to non-regressing tumors. In addition, the expression of the interleukin 2 receptor, an activation marker for T cells, was increased. However, there were no significant differences in class II MHC, CD1, intercellular adhesion molecule 1 (ICAM1), or melanoma-associated differentiation-antigen expression in these tumors. These data are consistent with melanoma regression being induced by activated CD4 T cells and do not seem to be related to the differentiation markers we have examined on these tumors.

Altered expression of major histocompatibility complex (MHC) antigens by epidermal tumours

Alteration in the major histocompatibility complex (MHC) antigen expression by cutaneous tumours may enable them to escape host defence mechanisms and to invade surrounding tissue. Immunohistochemical studies in a wide range of epidermally derived tumours demonstrated expression by keratinocytes of the class II molecule HLA-DR in squamous cell carcinoma (SCC) (2 of 8 cases) and keratoacanthoma (KA) (2 of 7 cases). Additionally, HLA-DP and DQ were expressed by single cases of SCC and KA, although, unlike the widespread distribution of DR, DP and DQ, were only present on keratinocytes adjacent to the inflammatory infiltrate. Therefore, keratinocytes in cutaneous tumours, like carcinoma cells of the colon and breast, may express class II MHC antigens during tumour growth. Beta-2-microglobulin (B2M), an invariant MHC class I marker, was absent in all cases of basal cell carcinoma. Variable loss of B2M was observed in squamous cell carcinoma, Bowen's disease and actinic keratoses, suggesting reduced B2M expression by dysplastic cells. However, the variability in B2M staining both between and within diagnostic categories restricts it's immunodiagnostic usefulness.