Immunohistochemical Studies of Infiltrating Cells in Early and Chronic Lesions of Psoriasis

Abstract

The expression of surface antigens on infiltrating cells, epidermal keratinocytes, and dendritic cells in biopsy specimens from 31 patients with psoriasis was examined immunohistochemically. The specimens were divided into early-phase and chronic-phase groups and then examined in a double blind manner. Among the infiltrating cells in the epidermis, CD4-positive cells were dominant in the early phase; CD8-positive cells were dominant in the chronic phase, resulting in a markedly decreased CD4/CD8 ratio in the latter. On the other hand, among the infiltrating cells in the dermal papillae, CD4-positive cells were dominant in both the early and chronic phases; both CD4-positive and CD8-positive cells were more dominant in the chronic phase than in the early one. However, the CD4/CD8 ratios were decreased in both the dermal papillae and the epidermis in the chronic phase. CD1-positive dendritic cells (probably Langerhans cells) were more numerous in the chronic phase than in the early phase. There were no significant differences between the early and chronic phases with regard to the expression of HLA-DR and HLA-DQ antigens on the infiltrating cells. However, the HLA-DR antigens and ICAM-1 (intracellular adhesion molecule-1) were more strongly expressed on epidermal keratinocytes in the chronic phase than in the early phase. LFA-1 alpha (lymphocyte function-associated antigen-1 alpha)-positive cells were also significantly more numerous in the chronic phase than in the early one, consistent with the expression of HLA-DR antigens and ICAM-1 on keratinocytes mentioned above. On the other hand, VLA-4 (integrin alpha 4 beta 1) positive cells were expressed more abundantly in the epidermis in the early phase than in the chronic phase. These results suggest, first, that the chronic phase of psoriasis is as immunologically active as or more active than the early phase. Second, CD4-positive T cells are more important than CD8-positive T cells in the early phase of psoriasis; CD8-positive rather than CD4-positive T cells are more important in the chronic phase. Third, the LFA-1/ICAM-1 pathway may play an important role with regard to cell adhesion of the infiltrating cells in the psoriatic lesions in disease exacerbation or prolongation, whereas the VLA-4/VCAM-1 (vascular cell adhesion molecule-1) pathway may be more important in disease onset.

Clinical immunology Density of Langerhans cells in chronic plaque psoriatic lesions before and after phototherapy

“…Immunohistochemical analysis of different stages of cellular infiltrate development in psoriasis showed a higher number of CD1a+ cells in chronic changes [24], but there are also studies which support the hypothesis of increased LCs density in early changes [21].…”

Upregulation of cathepsin S in psoriatic keratinocytes

“…It has been shown that the proteolytic actions performed by CATS within early endosomes of most of the professional APCs comprise degradation of MHC class II-associated invariant chain (1,8,27). Given this function, the upregulation of MHC class II-immunoreactivity in the psoriatic epidermis reported in this study and the ability of keratinocytes to synthesize MHC class II (16,30,58,59) we addressed the question whether CATS fulfills similar tasks in keratinocytes. Using a specific CATS inhibitor we showed that CATS has a distinct role in Ii processing as well as in MHC class II expression in keratinocytes.…”

Fumaric Acid Esters Suppress Peripheral CD4- and CD8-Positive Lymphocytes in Psoriasis

“…Taking into consideration the importance of immunological aspects in pathogenesis of psoriasis [8, 17, 18, 19, 20, 21], these results represent a promising basis for further studies.…”

“…However, some studies indicate the involvement of immunomodulating or immunosuppressive effects. Immunological changes could be observed both locally in psoriatic plaques [7, 8] as well as systemically [4, 9]. More detailed statements, particularly in long-term observations, are not available at the present.…”