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CD1 antigens are classified into at least three groups, CDla, CDlb, and CDlc. In order to delineate the localization of epitopes of CD1 antigens in human skin, we examined the irnrnunoreactivity of fourteen different CD1 antibodies (seven CDla, five CDlb, and two CDlc antibodies). The epitopes for CDla, CDlb, and CDlc are differentially localized on epidermal Langerhans cells, dermal dendritic cells, keratinocytes, the luminal portion of eccrine gland ducts, and the basement membrane zone in normal human skin.

The association of specific HLA-C nucleotide sequences with psoriasis vulgaris was investigated in 75 Japanese patients by the polymerase chain reaction method, followed by slot-blot hybridization using two specific oligonucleotide probes. The synthesized nucleotide primers were C180P, 5'-GACCGGGAGACACAGAAGTACAAG-3' (coding for amino acid residues 61 to 68 of the alpha 1 domain of the HLA-C molecule) and C243PR, 5'-GCTCTGGTTGTAGTAGCCGCG-3' (residues 82 to 88), respectively. The amplified sequence detected with the probe C208A (5'-AGGCACAGGCTGACCGA-3'), including the coding region for alanine at position 73, was significantly increased in frequency in the patients compared with the healthy individuals (81% versus 48%, relative risk = 4.7, chi 2 = 15.3, p less than 0.0001). This specific nucleotide sequence is common to Cw6 and Cw7, but some other HLA-C alleles including Cw4 and C blank (Cx52) also proved to have this sequence. It is suggested that alanine at position 73 of HLA-C molecules can be a good marker for psoriasis vulgaris and that this residue may play an important role in determining susceptibility to this disease.

Cellular DNA content was measured for the purpose of differentiating Spitz nevus from malignant melanoma using the cytofluorornetric technique. DNA was stained by 4', 6-diamidino-2-phenylindole, and measured by microfluorometer. Among 20 Spitz nevi examined, 18 of them showed a diploid DNA distribution histographic pattern similar to that of acquired pigmented nevi. The other two Spitz nevi had a few polyploid cells with the major population of cells containing diploid DNA content. In contrast, all malignant melanomas showed an aneuploid DNA distribution histographic pattern. The DNA index values of cells from Spitz nevi distributed in the similar range to that of acquired pigmented nevi and separated from those of malignant melanomas distributed in a much higher range. Our results suggest that cytofluorometric analysis of cellular DNA content reflects the biologic behavior more sensitively than do conventional clinical or histologic criteria, and that it serves as a useful aid for the differentiation of Spitz nevus from malignant melanoma.