Leu-11b (CD16) antigen expression on human keratinocytes

Expression of monocyte/macrophage markers (CD13, CD14, CD68) on human keratinocytes in healthy and diseased skin

The results of several investigations proved that, in special circumstances, human keratinocytes (HKs) synthesize and express cell surface moieties characteristic of effector and/or accessory cells of the immune system, such as CD16, CD36, HLA-DR, and intercellular adhesion molecule-1 (CD54), which are all detectable on the surfaces of macrophages. In the present study, skin biopsies from healthy volunteers, from positive tuberculin skin tests, and from patients with acute urticaria (AU), lichen planus (LP), psoriasis vulgaris (PV), mycosis fungoides (MF), and purpura pigmentosa chronica (PPC) were investigated by means of a multistep immunoperoxidase method to examine the reactivity of the HKs with a panel of monoclonal antibodies (MABs) characteristic of monocyte/macrophage cell lines. In biopsies obtained from positive tuberculin tests and from clinically involved skin of patients with LP, PV, MF, or PPC, a multifocal, positive peroxidase reaction was observed on the membranes of HKs of the basal and suprabasal cell layers when the MABs OKM13 (CD13), OKM14 (CD14), and Dako-Macrophage (CD68) were used. In contrast, specific staining of the HKs was not observed with the same antibodies in the biopsies of healthy volunteers or of patients with AU or in the uninvolved skin specimens obtained from the other patients. The HKs of PV, LP, MF, PPC, and AU patients and those of the healthy subjects all failed to give positive reactions when MABs against CD11b, CD15, or CD33 were used. The published data supplement the known surface characteristics of HKs, reflecting their stage of activation and differentiation.

Immune-associated surface markers of human keratinocytes

The results of a number of investigations have proved that human keratinocytes (HKs) possess the ability to synthesize and express cell surface moieties characteristic of effector and/or accessory cells of the immune system. The present paper summarizes the known immune cell surface features of HKs, reflecting their stage of activation and differentiation. The surface and functional characteristics of HKs suggest their monocyte/macrophage behavior, which fits in well with the presumed active involvement of HKs in the skin immune system.

Epidermal cell surface-associated IgG in patients with primary Sjögren's syndrome: in vitro evidence for immune complex binding

In vivo deposits of IgG have previously been demonstrated in the epidermal intercellular area of clinically unaffected skin from 68% of patients with primary Sjögren's syndrome (primary SS). This study compared circulating IgG from patients with primary SS with that from secondary SS in their ability to bind normal human epidermal cells in vitro. We observed a granular pattern of IgG binding to the normal epidermal cell surfaces with 9 of 18 sera from patients with primary SS (50%), 3 of 19 sera from patients with SS secondary to rheumatoid arthritis (16%) (p = 0.025), and none of 24 normal control sera (p less than 0.001). In a subsequent analysis of polyethylene glycol separated sera from two normal controls and two primary SS patients, the epidermal IgG binding capacity was found only in the precipitates of the patients. These findings support our previous hypothesis that the in vivo intraepithelial IgG deposits in primary SS patients are due, at least in part, to cell surface-bound immune complexes.

Immunopathological aspects of etretinate therapy in lichen planus

Biopsy specimens of involved and uninvolved skin were studied in 8 patients suffering from generalized lichen planus (LP) before and after successful etretinate treatment using murine monoclonal antibodies against several cell surface markers of effector and/or accessory cells of the immune system. In contrast to untreated LP-lesions, in biopsies obtained after etretinate therapy from healed involved skin a markedly disintegrated HLA-DR expression on keratinocytes and intraepidermal Langerhans cells and a nearly total loss of suppressor/cytotoxic T lymphocytes at the dermo-epidermal interface were found. Our data emphasize the key position of the class II antigen expression on various immunocompetent cells, as a marker for a cell-mediated immune reaction, on the other hand, stress the involvement of keratinocytes, Langerhans cells and suppressor/cytotoxic T lymphocytes in the pathogenesis of LP.