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The irritation response to anthralin was studied using the chamber-testing technique in 17 patients with vitiligo. Anthralin concentrations of 0.1%, 0.5%, 1%, and 5% in lanette wax were applied to both vitiliginous and adjacent pigmented skin for 24 h. The extent of the erythematous reaction was evaluated on the 2nd day after application. The visual assessment of the paired anthralin patches indicated that the erythema was more intense in pigmented skin than in vitiliginous skin in 15 out of 17 patients. Chromometer readings, however, clearly indicated that the erythematous response was stronger in the vitiliginous skin than in the pigmented skin, confirming the known fact that the human eye is not accurate in the quantitative assessment of complex colors. Immunophenotypification of cellular infiltrates, using the combination of different monoclonal antibodies and the peroxidase technique, showed that inflammatory cell infiltrates caused by the anthralin exposure contained increased numbers of granulocytes and monocytes in vitiliginous skin when compared with normal skin. The percentage of T-cell subsets, Langerhans cells, and mast cells in the same infiltrates of both types of skin were similar. Our results are discussed in accordance with the view that anthralin-induced radical species of the pigmented skin can be neutralized by the scavenging properties of melanin.

Absolute numbers of CD3+ T lymphocytes and their subpopulations were determined and statistically evaluated in the lesional skin of psoriasis, atopic dermatitis, nummular dermatitis, pityriasis rosea, and lichen planus. Skin sections were divided into horizontal layers and the numbers of CD3+ T cells as well as CD4+ inducer and CD8+ suppressor-cytotoxic T-cell subsets were counted. In addition, absolute numbers of the two subpopulations of inducer T cells, i.e., “memory” (4B4+ 2H4-) and “naive” (4B4- 2H4+) were evaluated. Unexpectedly, epidermal infiltration by T cells was highest in psoriasis and lowest in atopic dermatitis. In most cases, this exocytosis was dominated by CD8+ suppressor/cytotoxic T lymphocytes, with a minimal epidermal mean CD4/mean CD8 ratio of 0.04 in pityriasis rosea and a maximum of 0.48 in psoriasis. Inducer T cells within the epidermis were almost exclusively of the 4B4+ 2H4- “memory” T-cell subpopulation, whereas 4B4- 2H4+ “naive” T cells were extremely uncommon in lesional epidermis. Similar results were obtained for dermal T cells in all diseases studied, i.e., 4B4- 2H4+ “naive” T cells were relatively rare. Papillary dermis infiltration by T cells was highest in lichen planus where a mean CD4/mean CD8 ratio of 1.10, the minimum in this comparative study, was obtained. The mean CD4/mean CD8 ratio of the papillary infiltrate was highest in atopic dermatitis (4.12). Our results indicate disease-specific and significantly different infiltration patterns of T-lymphocyte subsets in the chronic inflammatory dermatoses investigated. The predominant presence of the CD4+ 2H4- “memory” subpopulation of CD4+ T cells in all diseases studied as well as in normal human skin (reported previously) seems to indicate that the skin immune system is rather unidirectional in its increase in this subpopulation of the inducer T-cell subset. This predominance of the “memory” subpopulation thus indicates that most T cells of normal and diseased human skin are already primed, i.e., have already met their specific ligand in a MHC II context.

The polymerase chain reaction (PCR) based on the selective amplification of a 530-bp fragment of the gene encoding the proline-rich antigen of Mycobacterium leprae was applied on sections of fixed or frozen biopsy samples from leprosy patients. A simple procedure for the extraction of DNA from M. leprae in clinical specimens that provided suitable template DNA for amplification was developed. When PCR was applied on frozen sections, positive amplification in samples from all untreated acid-fast bacillus (AFB)-positive patients and in samples from 56% of the untreated AFB-negative patients could be detected, while biopsy samples from patients with skin diseases other than leprosy were all PCR negative. With neutral Formalin-fixed biopsy samples, positive amplification in 92% of the samples from untreated AFB-positive patients and in 61% of the samples from untreated AFB-negative patients could be detected by PCR. Biopsy samples exposed to mercuric chloride or nonbuffered formaldehyde containing fixatives were not suitable for application of PCR. This PCR holds promise as a tool for studies on M. leprae infection.