Quantitative studies of the fate of epidermal Langerhans cells after X-irradiation of guinea-pig and mouse footpad skin

Eczematous dermatitis after vascular laser therapy: a report of two cases

Eczematous dermatitis was found in two port wine stain (PWS) lesions in two different individuals following variable pulsed 532-nm laser therapy. Both of the individuals described in this report had received low-dose superficial X-ray several years prior to the development of the eczematous dermatitis. The eczematous dermatitis in the PWS lesions was characterized by oozing, crusting, and pruritus, which showed a tendency to expand to other sites when exacerbated. Treatment with topical corticosteroid ointments produced some temporary improvement, but the dermatitis in both cases recurred when the topical medications were stopped. The mechanism of action for the development of an eczematous dermatitis in a PWS remains unclear, but may be related to multiple factors including abnormal hemodynamic forces resulting from the malformed vessels, an abnormal production of cytokines, local pathophysiological and immunological changes resulting from either the X-ray therapy or the laser therapy, and atopic constitution inherent in these individuals. These hypotheses and ideas need further study for additional insight into this rare, but reported adverse event.

The steady-state turnover of murine epidermal Langerhans cells

We have investigated the steady-state turnover of murine epidermal Langerhans cells (LCs) using an X-irradiation model, 3H-thymidine autoradiography and cultured epidermal sheet explants, and by assessing the LC population in normal mice. The LC density after whole-body irradiation without any cutaneous shielding was not significantly different from that in skin shielded during whole-body irradiation (P > 0.05), indicating that the additional irradiation to the skin did not contribute to a decrease in LC density. In both instances, the LC number gradually decreased in a linear fashion. The results indicate that epidermal LCs continuously leave the epidermis and are continually replaced by circulating precursor cells from the bone marrow at a steady rate. Autoradiographic studies after a pulse injection of 3H-thymidine showed a labelling index of 0.013%, indicating that local mitosis is not an important contributor to the maintenance of the epidermal LC population. Although local X-irradiation resulted in temporary reduction of LC density, epidermal sheet explant culture obtained immediately after local X-irradiation showed no difference in LC density as compared with control unirradiated skin, indicating that the decrease in LC density was not due to significant LC destruction. From these data, we calculated that the half-life of murine LCs in the epidermis is approximately 9 days.

Immunohistochemical staining of infiltrates in oral lichen planus

Immunohistochemical examination of lymphocyte and accessory cell infiltrates was performed in 24 cases of oral lichen planus using a double staining technique. The major population of the superficial stromal lymphocytes was T cells which were mostly composed of dominant CD 4+Leu8- (helper T cells) and lesser numbers of CD 8+11b- cells (cytotoxic T cells). Contrarily, many more CD 8+11b- cells than CD 4+Leu8- cells had infiltrated the epithelium. Some infiltrated T cells expressed interleukin-2 receptor and about half of cytotoxic T cells expressed class II antigen. HLA-DR-positive monocytes were also observed in both the superficial stroma and the epithelium. A number of HLA-DR-bearing CD 1+ cells (Langerhans/dendritic cells) and CD 11c+ cells (macrophages) were observed in the lower layers of the epithelium which were sometimes degenerative. Having significant correlation with the infiltration intensities of subepithelial macrophages and epithelial CD 8+ cells (cytotoxic/suppressor T cells), epithelial Langerhans cells variably infiltrated. Superficial stromal CD 8+ cells correlated with epidermal CD 8+ and CD 4+ cell (helper/inducer T cells) infiltrates. These findings are consistent with the notion that Langerhans cells and macrophages play an important role in antigen presentation, and suggest that cellular immunity, mediated by cytotoxic T cells with helper T cells, may be related to the pathogenesis of oral lichen planus.

Langerhans cells in human allergic contact dermatitis contain varying numbers of Birbeck granules. Double staining immunohistochemistry with OKT6 and Lag antibody

Dynamic changes in human Langerhans cells (LCs) were studied with OKT6, anti-HLA-DR antibody, and Lag antibody in allergic contact dermatitis (ACD). Both T6-positive (T6+) cells and Lag-positive (Lag+) cells in the epidermis decreased in number from 0 to 48 h, but then gradually increased after day 7 of ACD. Lag+ cells after day 7 manifested a variety of staining intensities from weak to strong. It was also shown, after day 7, that some T6+ cells were Lag negative whereas all Lag+ cells were T6 positive. Flow cytometric analysis suggested that Lag-strongly-positive cells and Lag-weakly-positive cells belonged to the same population, and that the relative amount of Lag antigens in T6+ LCs gradually increased after day 7. Immunoelectron microscopy revealed that the Lag-strongly-positive cells contained numerous Lag-reactive Birbeck granules (BGs) whereas the Lag-weakly-positive cells contained fewer BGs in the cytoplasm. In some Lag-weakly-positive cells, no BGs were detected.