Following extensive propagation in fibroblasts, human cytomegalovirus (HCMV) loses tropism for a number of otherwise natural host cells, in particular, endothelial cells. In this study, the hypothesis was tested that loss of endothelial tropism is associated with the appearance of genomic variants. Initial quantitative focus expansion assays on endothelial monolayers demonstrated that, while the laboratory strains AD169 and Towne failed to form detectable foci, 29 out of 30 recent clinical HCMV isolates had the potential to expand in endothelial cell culture. By longterm adaptation in fibroblast cultures, nonendotheliotropic strains could be selected from clinical HCMV isolates, while long-term endothelial-adapted strains of the same isolates retained both fibroblast tropism and endothelial tropism. Such differentially adapted isolate pairs always displayed genomic differences in restriction fragment length analyses. Coinfection of endothelial cells by two nonendotheliotropic HCMV strains yielded an endotheliotropic recombinant HCMV variant combining portions of the genomes of both parental viruses. When DNA purified from various isolates was transfected into fibroblasts, progeny virus retained the specific tropism of parental virus from which the DNA was isolated. These findings demonstrate that endothelial tropism is an inherent property of most clinical HCMV isolates and is determined by the viral genome. Although the specific determinants of HCMV cell tropism are still unknown, this study provides the first evidence for a genetic contribution.

Purpose: Humoral allograft rejection is a defined mechanism for cardiac and renal graft dysfunction; C4d deposition, a stable component of complement activation, inversely correlates with graft survival. With the recent recognition of humoral rejection in lung grafts, we examined C4d's role as a prognostic adjunct in lung allografts. Material and Methods: Twenty‐three lung recipients underwent biopsies for deterioration in clinical status or routine surveillance. Clinically unwell patients possessed acute rejection or bronchiolitis obliterans syndrome (BOS). Biopsies attributable to infection were excluded from the study. In addition to routine light microscopy, an attempt was made to correlate the clinical status and morphologic findings with the pattern of C4d deposition and also to compare these clinical and morphologic parameters with the other assessed immunoreactants. Panel reactive antibody testing was also carried out at various points in their post transplantation course whereby in 6 of the cases the samples were procured at exactly the same time as the tissue samples. Results: The patients were segregated into two groups: those patients with recurrent acute rejection and those with BOS. In those patients with symptomatic acute rejection, all biopsies showed light microscopic and immunofluorescent evidence of humoral allograft rejection. The level of C4d was positively correlated with the degree of parenchymal injury, the hallmark being one of septal capillary necrosis. In addition, high and intermediate levels of C4d correlated with a clinical diagnosis of acute rejection. C4d was the strongest predictor of parenchymal injury and of the clinical status (p < .0001) compared to other the immunoreactants C1q, C5b‐9 and immunoglobulin. There was no specific correlation between C4d deposition and the presence of acute cellular rejection. In those patients fulfilling clinical criteria of BOS, deposits of C4d as well as other immunoreactants were found in the bronchial wall as opposed to the rarity of this finding in bon‐BOS patients. However the only statistically significant predictor of BOS was bronchial wall deposition of C1q. In no case were panel reactive antibodies at significant levels discovered post transplantation. Conclusions: In the context of acute rejection, C4d deposition correlates with clinical evidence of rejection and the degree of humoral rejection assessed pathologically; there is no association with the presence of histocompatibility related antibodies. It is a more specific predictor of allograft status compared to other immunoreactants. C4d deposition within the bronchial wall is a feature of BOS and hence may be used as a marker of chronic graft dysfunction. The antigenic target resulting in C4d deposition may not be histocompatibility related.

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A rare case of a spindle cell (sarcomatoid) B-cell lymphoma is described. The patient, a 48-year-old male, presented with a several month history of an enlarging lesion on the scalp. Although there have been a few recent reports of cutaneous sarcomatoid lymphomas, this case is especially unusual because it presented as a scarlike plaque rather than a tumor and microscopically exhibited a prominent myxoid matrix. Given these features, the lesion was initially interpreted as an atypical fibromucinosis. The differential diagnosis included fibromucinous lesion consistent with variant of lichen myxedematosus, spindle cell carcinoma, spindle cell melanoma, atypical fibroxanthoma, and atypical smooth muscle tumors. Initial immunoperoxidase studies demonstrated negative staining for CD68, factor XIIIa, CD57, cytokeratin(AE1/AE3), S100, EMA, and vimentin, essentially ruling out the previously mentioned neoplasms. Subsequently, strong positive staining for LCA(CD45RB) and CD20 was demonstrated characteristic of a B-cell lymphoma. The patient underwent local radiotherapy with complete resolution. Although all variants of cutaneous sarcomatoid B-cell lymphomas are rare, it is imperative to consider them in the differential diagnosis of otherwise difficult to categorize spindle cell proliferations. This includes neoplasms and, based on the current case, fibromucinoses as well.

Dermatomyositis, a connective tissue disease syndrome where antibodies to the endothelium of the microvasculature of the skin, muscle and lung are implicated in lesional propagation, is characterized by photodistributed erythema, heliotrope rash, Gottron's papules, muscle weakness and interstitial pulmonary fibrosis. Endotheliotropic viruses and underlying neoplasia are among the inciting triggers. Uncommon drugs, namely the lipid-lowering agents, have been implicated in dermatomyositis. The patient, a 57-year-old man, developed a photodistributed rash and muscle weakness following treatment with the antifungal medication, terbinafine. A skin biopsy was performed, showing an atrophying interface dermatitis with pandermal mucinosis and striking vasculopathic changes including endothelial cell necrosis with denudement and basement membrane zone reduplication. Ultrastructural studies confirmed the presence of endothelial cell injury. Direct immunofluorescent testing showed prominent staining of C5b-9 along the dermal-epidermal junction and within the vasculature. Western blot studies showed strong seroreactivity of his serum to an endothelial-based protein weighing 45,000, a common target described in other microvascular injury-based syndromes. We have shown a temporal association between use of terbinafine and the development of dermatomyositis. The exact basis remains speculative. One potential hypothesis is based on the fact that terbinafine, the active agent in terbinafine, triggers apoptosis of human endothelial cells in culture. Enhanced endothelial cell apoptosis results in the displacement of various cellular antigens creating a state of neoantigenicity; its attendant sequelae is held to be one of anti-endothelial cell antibody formation, a defining pathogenetic event in the evolution of dermatomyositis. The second may be because of the effects of the drug on the promotion of an interferon-rich T-helper-1-dominant cytokine milieu.