Human epidermal Langerhans cells express the ICAM-3 molecule. Immunohistochemical and immunoelectron microscopical demonstration.

Three ligands have been described for the leucocyte integrin LFA-1, namely intercellular adhesion molecule (ICAM)-1, ICAM-2, and ICAM-3. ICAMs show differences in tissue distribution and inducibility. The recently described ICAM-3 is highly expressed on resting lymphocytes, monocytes and neutrophils. Here, we demonstrate that the whole human epidermal Langerhans cell (LC) population expresses this molecule. Immunohistochemical staining of skin sections with an anti-ICAM-3 monoclonal antibody displayed reactivity with dendritic epidermal cells regularly distributed along the epidermis. Highly-sensitive immunoelectron microscopy procedures, performed on freshly suspended epidermal cells both at transmission and scanning electron microscopic levels, enabled demonstration that the whole LC population expresses cell surface ICAM-3. In contrast, keratinocytes and melanocytes were consistently negative. The prominent expression of ICAM-3 by resident LC could imply a crucial part for this molecule in leucocyte-intercellular interactions in the skin.

bcl-1, bcl-2, p53, c-myc, and lyt-10 analysis in cutaneous lymphomas.

In the present study we investigated the pathogenetic role of c-myc, bcl-2, and lyt-10 oncogenes, bcl-1 locus, and p53 suppressor gene in a representative panel of cutaneous lymphomas, including 25 cases of cutaneous B cell lymphoma (CBCL) and 29 cases of cutaneous T cell lymphoma (CTCL). In our analysis four cases of CBCL were found rearranged for bcl-2 and two for the bcl-1 locus. Two cases of CTCL and one case of CBCL were found rearranged for lyt-10. No rearrangements of c-myc oncogene were found in CBCL. Analysis of p53 gene showed mutation only in one case of mycosis fungoides in tumoral stage, at codon 163 of p53 gene (TAC-->CAC; Tyr--> Asp). Our data suggest that in primary CBCL bcl-2 oncogenes and bcl-1 locus are rarely involved. Furthermore, in primary CTCL p53 gene is not affected at significant frequency. The occurrence of p53 mutation in a patient affected by mycosis fungoides in tumoral stage may represent an involvement of p53 gene in tumor progression of CTCL, a finding observed in several types of human cancer.