Stephen M. Breathnach

Effects of topical corticosteroid therapy on Langerhans cell antigen presenting function in human skin.

We have investigated the mechanisms by which topical corticosteroids modulate cutaneous immune reactions in man. Volunteers applied clobetasone butyrate 0.05% (Eumovate®; EV), betamethasone valerate o‐I% (Betnovate®; BV), clobetasol propionate 0.05% (Dermovate®; DV), and control vehicles twice daily to forearm skin for 7 days. Steroid therapy significantly decreased the number of HLA‐DR/T6 (CDIa) positive Langerhans cells (LCs) per mm2 in suction blister‐derived epidermal sheets, expressed as a mean percentage of controls, as follows: EV 69–2%; BV 67.3%; DV 37.8%. LC antigen presenting capacity was determined in the allogeneic and autologous epidermal cell‐lymphocyte reactions. The LC‐dependent allostimulatory capacity of epidermal cells, expressed as a mean percentage of controls, was also significantly reduced by steroid therapy: EV 45.1%; BV 4I.9%; DV 23.4%. Following therapy with clobetasol propionate 0.05%, the capacity of epidermal cells to present tetanus toxoid to, and to augment concanavalin A mediated lymphocyte stimulation of, autologous lymphocytes was reduced to 33.6% and 19.7% respectively of controls. Depression of epidermal cell allostimulatory capacity was not the result of a steroid‐induced decrease in the production of epidermal cell‐derived thymocyte activating factor (ETAF)/interleukin I by keratinocytes, since it could not be reversed by addition of exogenous interleukin I. Indomethacin, added to block any potential prostaglandin synthesis during the culture period, did not restore the allostimulatory capacity of epidermal cells from steroid‐treated sites. Addition of epidermal cells from DV‐treated sites depressed the capacity of control epidermal cells to stimulate lymphocytes in the allogeneic epidermal‐lymphocyte reaction. Our results demonstrate that the anti‐inflammatory action of topical corticosteroids in man is associated not only with a reduction in the number of HLA‐DR/T6 positive LCs, but also with a marked decrease in Langerhans cell‐dependent T lymphocyte activation. The effects of the different steroids on both of these parameters correlated with their potency as determined in the standard occlusive vasoconstrictor assay.

PUVA therapy decreases HLA-DR+ CD1a+ Langerhans cells and epidermal cell antigen-presenting capacity in human skin, but flow cytometrically-sorted residual HLA-DR+ CD1a+Langerhans cells exhibit normal alloantigen-presenting function

We have investigated the effects of PUVA therapy on human Langerhans cell (LC) immunophenotype and function. Epidermal sheets were obtained from exposed, and control shielded, forearm skin at the end of a course of PUVA therapy, in patients receiving treatment routinely for a variety of dermatoses. PUVA therapy decreased the overall number of HLA‐DR+ CD1a+ LCs in epidermal sheets, and in epidermal cell (EC) suspensions examined using a fluorescence activated cell sorter (FACS). PUVA therapy also reduced the overall EC allostimulatory capacity in the allogeneic epidermal cell‐lymphocyte reaction (ELR), and the capacity of ECs to present tetanus toxoid to, and augment concanavalin A‐mediated stimulation of, lymphocytes in the autologous ELR. Depressed allostimulation by ECs from PUVA‐treated skin could not be restored by indomethacin (added to block prostaglandin synthesis). The reductions in LC numbers and EC allostimulatory capacity varied according to dose, and time since cessation, of PUVA therapy, and in individual patients were of comparable degree. By contrast, the allostimulatory capacity of residual LCs from PUVA‐treated skin (purified using the FACS) did not differ from that of purified control LCs. PUVA‐induced suppression of cutaneous immune responses, therefore, results at least in part from an overall impairment of EC antigen‐presenting capacity. Residual HLA‐DR+ CDla+ LCs in PUVA‐treated skin which retain their alloantigen‐presenting function may represent a subgroup of PUVA‐resistant LCs; alternatively, these cells may be as yet unaffected because they have only recently migrated into the epidermis.

Amyloid elastosis: Analysis of the role of amyloid P component

We report the second case of amyloid elastosis. Our patient had an underlying primary systemic amyloidosis with lambda light chain paraproteinemia. Salient clinical features included a sclerodermatous facial appearance, cordlike thickening of superficial blood vessels, neck skin resembling that in pseudoxanthoma elasticum, livedo reticularis-like changes on the trunk, Raynauds phenomenon, arterial and venous thromboses, and the nephrotic syndrome. Amyloid deposits were present in the dermis, around appendages, in blood vessel walls, and in a striking distribution surrounding individual elastic fibers, that appeared shortened and fragmented. Immunofluorescence, electron microscopic, and immunoultrastructural studies with antibodies to lambda light chain, localized the amyloid deposits to the region of the elastic fiber microfibrils, with which amyloid P component (AP) is invariably associated in normal tissues. Because AP binds amyloid fibrils, codistribution of amyloid deposits and AP in amyloid elastosis strongly supports the theory that elastic fiber-associated AP may act as a nidus for amyloid deposition.

Immunopathology of cutaneous graft-versus-host disease.

Graft-versus-host disease (GVHD) occurs when lymphoid cells from an immunocompetent donor are introduced into a histoincompatible recipient that is incapable of rejecting them. GVHD is seen most commonly as a complication of therapeutic bone marrow transplantation, and the skin is a primary target organ. As GVHD mimics several important skin diseases both clinically and histologically, it provides a useful model for studying the immunopathologic features of epidermal cell-lymphocyte interactions.

Deposition of C3, C9 neoantigen and vitronectin (S-protein of complement) in lichen planus pemphigoides.

We have compared the distribution of C3, C9 neoantigen (C9n) and vitronectin at the dermoepidermal junction in lichen planus pemphigoides with that in bullous pemphigoid. Eight out of 30 biopsies from patients with lichenoid lesions had linear C3 deposition at the basement membrane zone (BMZ); four of these patients had bullae and fulfiled the criteria for lichen planus pemphigoides. C9n immunoreactivity was detected as a linear or an intermittent linear granular band at the BMZ only in these four patients, suggesting a role for the membrane attack complex of complement (MAC) in the pathogenesis of blister formation in lichen planus pemphigoides. Faint linear deposition of vitronectin, in addition to C9n, at the BMZ was seen in two of the four cases of lichen planus pemphigoides and three of six cases of bullous pemphigoid. This suggests that vitronectin may be deposited in association with C9n not only as part of the non‐lytic SC5b‐9 complex, but also as a regulatory step following the lytic action of MAC. A regulatory function for vitronectin in limiting tissue damage following activation of MAC is supported by our finding of a heavy deposition of vitronectin in association with C9n in a lichen planus pemphigoides patient in whom bulla formation had ceased.

Flow cytometric analysis and sorting of HLA-DR+CD1+ Langerhans cells

There is a considerable need for reliable methods for enumeration and enrichment of Langerhans cells (LCs), since they continue to be the subject of intensive investigation in normal and diseased skin. It has been claimed that standard labelling with either anti‐HLA‐DR or OKT6 antibodies alone may fail to identify potentially important subsets of LCs with the phenotypes HLA‐DR+CD1− and HLA‐DR−CD1+. We report here on flow cytometric analysis of suction blister‐derived normal epidermal cell (EC) suspensions, double stained with phycoerythrin‐conjugated anti‐HLA‐DR and fluoresceinated OKT6. In seven separate experiments, no evidence for the existence of either HLA‐DR+CD1− or HLA‐DR−CD1+ECs was obtained. We found that HLA‐DR+CD1+LCs, which constituted a mean of 2.5% (±0.3 SEM) of all ECs, could be readily identified on the basis of fluorescence, and that their light scatter characteristics were those of moderately sized cells of low granularity. We further describe our method for flow cytometric enrichment of such HLA‐DR+CD1+ LCs for functional studies, based on selection on both fluorescence and light scatter criteria. Enrichment is to greater than 90% purity, and the method is applicable to the small number of ECs (approximately 1 × 106) obtained from a suction blister.

Monoclonal antibodies in dermatologic research. Studies with a unique cell-surface antigen defined specifically for keratinocytes by a monoclonal antibody

Basic principles of production of monoclonal antibodies are discussed in this paper. In order to illustrate the usefulness of such production, studies of a new monoclonal antibody designated KF-2 which defines a unique cell-surface antigen found exclusively in the stratum spinosum of man and lower primates are recounted.