No abstract

Complementary DNA cloning of the 130-kD pemphigus vulgaris (PV) autoantigen (PVA) has indicated that it is a member of the cadherin family of Ca2-dependent cell adhesion molecules. By homology with typical cadherins, PVA has five extracellular domains (EC1 through EC5). To localize immunogenic domains and to determine whether antibodies against them might be pathogenic, we produced,8-galactosidase fusion proteins with cDNA encoding different portions of the extracellular domains of PVA (ECi-2, EC3-5, and each individual domain). Immunoblot analysis of these fusion proteins with 23 PV patients' sera demonstrated that major immunogenic regions of PVA are located on the EC1, EC2, and EC4 domains. IgG was affinity-purified from PV sera on fusion proteins representing the amino (EC1-2) and carboxy (EC3-5) terminus of the extracellular PVA, and injected into neonatal mice. PV IgG affinity-purified on the EC1-2 fusion protein caused suprabasilar acantholysis, the typical histological finding of PV, but IgG affinity-purified on the EC3-5 fusion protein or,6-galactosidase alone did not. These results indicate that at least one pathogenic epitope, which is sufficient to cause suprabasilar acantholysis in neonatal mice, is located on the amino-terminal region of PVA, an area thought to be important in cadherin homophilic adhesion. (J. Clin. Invest. 1992. 90:919-926.)

Transmission of HIV-1 is predominantly restricted to macrophage (Mphi)-tropic strains. Langerhans cells (LCs) in mucosal epithelium, as well as macrophages located in the submucosal tissues, may be initial targets for HIV-1. This study was designed to determine whether restricted transmission of HIV-1 correlates with expression and function of HIV-1 co-receptors on LCs and macrophages. Using polyclonal rabbit IgGs specific for the HIV co-receptors cytokines CXCR4 and CCR5, we found that freshly isolated epidermal LCs (resembling resident mucosal LCs) expressed CCR5, but not CXCR, on their surfaces. In concordance with surface expression, fresh LCs fused with Mphi-tropic but not with T-tropic HIV-1 envelopes. However, fresh LCs did contain intracellular CXCR4 protein that was transported to the surface during in vitro culture. Macrophages expressed high levels of both co-receptors on their surfaces, but only CCR5 was functional in a fusion assay. These data provide several possible explanations for the selective transmission of Mphi-tropic HIV variants and for the resistance to infection conferred by the CCR5 deletion.

Autoantibodies from bullous pemphigoid (BP) patients define a 230-kD protein found in the basement membrane of stratified squamous epithelia. The purpose of this study was to isolate and characterize a cDNA clone with coding sequences for BP antigen. Poly(A+) RNA derived from total RNA of cultured keratinocytes was used, with oligo-dT priming, to construct a cDNA library in the Xgtl1 expression vector, which was screened by the immunoperoxidase method with one BP serum. One darkly stained clone, called here the BP clone, was further characterized. 9 of 9 BP sera, but none of 6 normal and 11 pemphigus sera, bound the plaques of this BP clone. Furthermore, BP IgG affinity purified on plaques of this clone, but not unrelated clones, bound the epidermal basement membrane by immunofluorescence and immunoprecipitated the 230-kD BP antigen from extracts of cultured keratinocytes. Eco RI digestion of the BP clone's cDNA insert demonstrated a 680-and 1,500-bp fragment. Northern blots of total keratinocyte RNA showed that complementary riboprobes transcribed from both fragments hybridized to a 9-kb RNA. Dideoxy DNA sequencing from the 5' end of the BP cDNA demonstrated a 1,992-bp open reading frame, encoding a peptide of 76 kD. This BP cDNA clone will be valuable for understanding the protein structure, expression, and gene organization of BP antigen.