SummaryThe Duffy antigen/receptor for chemokines (DARC), first identified on erythrocytes, functions not only as a promiscuous chemokine receptor but also as a receptor for the malarial parasite, Plasmodium vivax. The recent finding that DARC is ubiquitously expressed by endothelial cells lining postcapillary venules provides a possible insight into the function of this receptor because this anatomic site is an active interface for leukocyte trafficking. However, the biological significance of DARC is questionable since it has not yet been determined whether individuals lacking the expression of this protein on their erythrocytes (Duffy negative individuals), who are apparently immunologicaUy normal, express the receptor on endothelial cells. However, we report here that DARC is indeed expressed in endothelial cells lining postcapillary venules and splenic sinusoids in individuals who lack the erythrocyte receptor. These findings are based on immunohistochemical, biochemical, and molecular biological analysis of tissues from Duff-y negative individuals. We also present data showing that, in contrast to erythrocyte DAILC, cells transfected with DARC internalize radiolabeled ligand. We conclude that the DARC may play a critical role in mediating the effects of proinflammatory chemokines on the interactions between leukocyte and endothelial cells since the molecular pathology of the Duffy negative genotype maintains expression on the latter cell type.

Sinonasal undifferentiated carcinoma (SNUC) is an uncommon and highly aggressive neoplasm of the paranasal sinuses and nasal cavity. Its undifferentiated histologic appearance often requires immunohistochemical studies to distinguish it from other high-grade neoplasms. Due to the rarity of SNUC, its immunohistochemical staining profile has been incompletely characterized, and little work has been done on its expression of the markers for human papillomavirus (HPV). Our objective is to expand our knowledge of its immunophenotype and its association with HPV in order to define markers with mechanistic potential in the disease process, or of possible therapeutic importance. A total of five patients (one woman and four men) with SNUC, ranging in age from 26 to 75 years (mean 56.8 years) were compared to five patients (five men) with poorly differentiated squamous cell carcinoma (PDSCC), ranging in age from 53 to 75 years (mean 62.2 years). PDSCC was chosen as a control, given its well-reported immunohistochemical profile and negativity for HPV markers. The immunohistochemical panel included: CK7, CK19, EMA, NSE, chromogranin, p53, CK5/6, p63, CK14, S100, HMB-45, desmin, muscle specific actin, and CD45. Additionally, tests for p16, EBV, and HPV (subtypes 6, 11 16, 18) were performed. The diagnosis of SNUC was confirmed in all cases by histology and immunohistochemical stains. An interesting finding of strong diffuse positivity for p16 was noted in all SNUC cases, compared to only two of five PDSCC that were positive for p16. HPV DNA was not detected in any SNUC cases or any cases of PDSCC. All SNUC cases demonstrated over expression of p16 in the absence of HPV DNA expression. This may represent residual epithelial p16 staining, which is normally present in the sinonasal tract. Due to the rarity of SNUC, more cases will need to be evaluated to confirm the absence of HPV DNA.

Immunohistochemical studies were done on formalin-fixed, paraffin-embedded tissues to evaluate the specificity of a newly developed monoclonal antibody (9C5) against tartrate-resistant acid phosphatase. Sections from 195 specimens were examined, which included 33 types of tissues/organs. These tissues included normal, inflammatory, and neoplastic processes. Neoplastic tissues from 14 patients with hairy cell leukemia served as positive controls. Epitope enhancement was accomplished either by microwave irradiation in citrate buffer or by boiling in water followed by trypsin digestion. Tissues were reacted with monoclonal antibody 9C5 and stained with either the avidin-biotin peroxidase method or the alkaline phosphatase anti-alkaline phosphatase method. The hairy cells of all cases of hairy cell leukemia reacted positively with 9C5. Other positively stained cells included osteoclasts, activated macrophages and giant cells. Immunohistochemical studies with 9C5, when interpreted within the context of the specificity of this antibody, are useful for the diagnosis and assessment of treatment results for hairy cell leukemia. Monoclonal antibody 9C5 also may be useful as a marker for osteoclasts and the activated macrophages and for the diagnosis of disorders involved by these cells.

Lymphomas involving the breast account for approximately 2% of extranodal and <1% of all non-Hodgkin lymphomas. Our aim in this study was to classify breast lymphomas using the World Health Organization classification and then compare this classification with clinical, histologic, and radiologic findings as well as survival. The study group included 106 patients with breast lymphoma (105 women and 1 man). The neoplasms were divided into 2 groups based on extent of disease at initial diagnosis: localized disease (n=50) and disseminated disease (n=56). The follow-up period ranged from 4 to 252 months (median, 49 mo). Almost all (97%) patients presented with a palpable breast mass or masses. In the localized group, diffuse large B-cell lymphoma (DLBCL) was most frequent (n=32, 64%). In the disseminated group, follicular lymphoma was most frequent and exclusive to this group (P=0.0004). Mucosa-associated lymphoid tissue lymphomas occurred in both groups without a significant difference in frequency. A variety of other types of B-cell and T-cell non-Hodgkin lymphomas and classical Hodgkin lymphoma involved the breast at much lower frequency; most of these neoplasms involved the breast as part of disseminated disease. The clinical presentation correlated with radiologic findings: localized lymphomas presented as solitary masses, whereas disseminated lymphomas commonly presented as multifocal masses. There was a significant difference in the disease-free survival between patients with localized and disseminated DLBCL (P=0.003). In the disseminated group, patients with DLBCL had a worse disease-free survival compared with patients with mucosa-associated lymphoid tissue lymphoma or follicular lymphoma (P=0.01).

Human serum contains 2 isoforms of type-5 tartrate-resistant acid phosphatase (TRACP): 5a and 5b. TRACP-5b is osteoclastic. Our goal was to determine if serum TRACP-5a could originate from inflammatory macrophages (MPhi). We stained 246 paraffin-embedded tissue samples for TRACP using monoclonal antibody 9C5 (mab9C5) to isoforms 5a and 5b and a novel mab220 specific to isoform 5a. CD68 and lysozyme were also stained. MPhi of chronic and granulomatous inflammation and in tissues that undergo strong antigenic stimulation were strongly positive for TRACP, more so with mab220 than with mab9C5. Noninflammatory MPhi in lymph node sinuses or germinal centers and red pulp MPhi of spleen were weak or negative for TRACP. Marginal zone lymphocytes and sebaceous glands of skin were weakly positive for TRACP. Tissue mast cells displayed strong TRACP staining. Neuroendocrine cells of gastrointestinal tissues were strongly immunoreactive with mab9C5 but negative with mab220. Restricted expression of TRACP primarily in inflammatory MPhi supports our hypothesis that circulating TRACP-5a could be a biomarker of chronic inflammatory disease activity.