We have shown that binding of bullous pemphigoid (BP)-patient IgG (BP-IgG) causes the internalization of BP180 from the cell membrane. This study examined whether BP-IgG treatment can deplete cultured keratinocytes of BP180, how it affects cellular levels of alpha6 and beta4 integrins (by western blot analysis using monoclonal antibodies to these antigens), and whether it reduces adhesion of cells to the culture dish (by a vibration detachment assay). All BP-IgG or BP sera with high values of BP180-ELISA from 18 BP patients before and after oral corticosteroid treatment showed dramatically decreased BP180 in cells after 6 hours of BP-IgG stimulation, whereas alpha6 and beta4 integrin levels were not decreased. Even IgG from patients in whom oral corticosteroid had suppressed active blistering could deplete cells of BP180, as long as sera retained a high value of BP180-ELISA. On the other hand, reduction of cell BP180 content increased detachment of cells from the dish. These results suggest that BP-IgG reduces hemidesmosomal BP180 content, weakening the adhesion of hemidesmosomes to the lamina densa. In the presence of BP180 deficiency, inflammation generated by BP180 immune-complex formation might then tear the weakened lamina lucida, and this could lead to generation of the BP-specific split at the lamina lucida.

Pemphigus vulgaris (PV) is an autoimmune blistering disease, characterized by the loss of cell-cell adhesion between epidermal keratinocytes and the presence of autoantibody against desmoglein 3 (Dsg3), which provides adhesive integrity to desmosomes between adjacent keratinocytes. We have previously shown that PV-IgG purified from patients depletes desmosomes of Dsg3. However, PV-IgG contains not only antibodies against a variety of different epitopes of Dsg3 but also against other unknown antigens. Therefore, we examined whether the Dsg3-depleting activity of PV-IgG is generated specifically by antiDsg3 activity in a human squamous cell carcinoma cell line (DJM-1) and normal human keratinocytes by using four different pathogenic and nonpathogenic monoclonal antibodies against Dsg3. We demonstrate that these monoclonal antibodies deplete cells and desmosomes of Dsg3, as PV-IgG does. Individual monoclonal anti-Dsg3 antibodies display characteristic limits to their Dsg3-depleting activity, which correlates with their pathogenic activities. In combination, these antibodies exert a cumulative or synergistic effect, which may explain the potent Dsg3-depleting capability of PV-IgG, which is polyclonal. Finally, although Dsg3-depletion activity correlated with AK-monoclonal antibody pathogenicity in mouse models, the residual level of Dsg3, when below ϳ50%, does not correlate with the adhesive strength index in the present study. This may suggest that although the Dsg3 depletion is not indicative for adhesive strength, the level of Dsg3 can be used as a read-out of pathogenic changes within the cell and that the Dsg3 depletion from desmosomes plays an important role in skin fragility or susceptibility to blister formation in PV patients.Pemphigus is a group of an autoimmune blistering diseases that includes two major types; i.e. pemphigus vulgaris (PV), 2 characterized by suprabasal acantholysis (the loss of cell-cell adhesion between keratinocytes) in the epidermis and autoantibodies against Dsg3 (1-4), and pemphigus foliaceus, characterized by superficial acantholysis in the granular cell layer of the epidermis and autoantibodies against Dsg1 (5, 6). Dsg3 and Dsg1 are members of the desmosomal cadherins that provide adhesive integrity to desmosomes between adjoining keratinocytes in the epidermis; the former distributes primarily in the deeper epidermis, whereas the latter is localized to the superficial epidermis. This distribution profile of these target antigens, Dsg3 and Dsg1, of PV and pemphigus foliaceus autoantibodies explains the characteristic clinical features and histopathological localization of acantholysis in their respective diseases. PV, but not pemphigus foliaceus, affects the mucous membrane, where Dsg3 is localized but Dsg1 is rarely expressed (7-10).Recent work has suggested that two principal hypotheses emerge as pathomechanisms underlying the generation of PV blisters (4, 11). The first proposes that anti-Dsg3 antibody-dependent steric hindrance interferes with intercellular adhesive function(s...

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Sex differences were observed in host resistance to Mycobacterium marinum infection in mice. Males were found to be more susceptible than females in terms of mortality, incidence of gross skin lesions, and bacterial load in the lungs and spleen. The degree of sex differences varied from strain to strain of test mice, in the order C3H1/I1e, A/J, and BALB/c > DBA/2, B10.A, and C57BL/6, on the basis of survival time and multiplication of organisms in the visceral organs. Although this ordering corresponded to the susceptibilities of both male and female mice to the organisms, much greater strain dependency was seen in males than in females. Castration caused an increase in the host resistance of males, but this effect was substantially reversed by continuous testosterone treatment. Testosterone also increased the susceptibility of female mice to this infection. These findings imply that the male sex hormone is involved in the lowered anti-M. marinum resistance of males. Although athymic mice were more susceptible than euthymic mice, a substantial degree of sex difference was also observed in the T-cell-depleted animals, indicating that natural host resistance to this infection is sex dependent. Indeed, more efficient macrophage mobilization at the site of infection was seen in females than in males. Although female T-cell transplantation improved the lowered resistance of athymic mice, there was a sex difference in bacterial growth in the lungs. This implies that sex hormones affect T-cell functions. Sex differences in host resistance have been reported in mycobacterial infections, such as those due to Mycobacterium lepraemurium (6) and the M. avium complex (33), in mice. Males are more susceptible to these infections than are females; hence, participation of sex hormones in this phenomenon has been suggested. In humans, males predominate in the incidence of M. avium complex and M. kansasii infections (1, 21, 27, 34). Estrogens increase the resistance of host animals to infections such as those caused by Salmonella (20), Streptococcus (20), Pasteurella (20), and Trypanosoma (17) species. However, it has been reported that resistance to listerial (24, 25), staphylococcal (32), gonococcal (15), and chlamydial (26) infections is conversely reduced by the same sex hormone. In Leishmania major infection, orchidectomy causes increased resistance in male mice and administration of testosterone decreases anti-L. major resistance in female mice (18). We previously reported that sex differences in host resistance to M. avium complex infection in BALB/c mice are partly attributable to the antimicrobial activity of host macrophages (M@). Specifically, peritoneal M4) from female mice show more potent anti-M. avium complex activity than do M4 from male mice (33). However, detailed mechanisms of the sex differences in host resistance to mycobacterial infections still await elucidation. M. marinum is the causative agent of swimming pool granuloma or fish tank granuloma in humans, and a similar disease is produced in experimental an...