Evaluation of a Rapid Immunochromatographic Test for Serodiagnosis of Visceral Leishmaniasis

The purpose of this study was to compare the performance of a rapid immunochromatographic dipstick test for the qualitative detection of circulating antibodies to the leishmanial recombinant antigen K39 with that of a classical immunofluorescent antibody test for serodiagnosis of visceral leishmaniasis. Sera from 143 Italian subjects, including 69 patients with clinically suspected visceral leishmaniasis, 23 patients with hypergammaglobulinemia and 51 healthy controls, were tested. The immunochromatographic test was performed according to the manufacturer's instructions, using antigen-impregnated nitrocellulose paper strips. The immunofluorescent antibody test was performed according to an established method, using promastigotes of Leishmania infantum zymodeme Montpellier 1 as antigen. In 11 patients, diagnosis of active Leishmania infection was established by microscopic examination of biopsy samples and/or clinical response to meglumine antimoniate. Results of the two tests correlated for all but two sera examined. In two patients, one with proven infectious mononucleosis and one with bacterial pneumonia, the immunofluorescent antibody test was positive and the dipstick test was negative. In the restricted sample of patients in whom a definitive diagnosis was established, the immunochromatographic test was positive in 11 of 11 patients with confirmed Leishmania infection and negative in 103 of 103 subjects who either had other documented diseases or were healthy controls, showing 100% sensitivity and 100% specificity. Electronic Publication     

ALK Expression Defines a Distinct Group of T/Null Lymphomas (“ALK Lymphomas”) with a Wide Morphological Spectrum

The t(2;5)(p23;q35) translocation associated with CD30-positive anaplastic large cell lymphoma results in the production of a NPM-ALK chimeric protein, consisting of the N-terminal portion of the NPM protein joined to the entire cytoplasmic domain of the neural receptor tyrosine kinase ALK. The ALK gene products were identified in paraffin sections by using a new anti-ALK (cytoplasmic portion) monoclonal antibody (ALKc) that tends to react more strongly than a previously described ALK1 antibody with the nuclei of ALK-expressing tumor cells after microwave heating in 1 mmol/L ethylenediaminetetraacetic acid buffer, pH 8.0. The ALKc monoclonal antibody reacted selectively with 60% of anaplastic large cell lymphoma cases (60 of 100), which occurred mainly in the first three decades of life and consistently displayed a T/null phenotype. This group of ALK-positive tumors showed a wide morphological spectrum including cases with features of anaplastic large cell lymphoma “common” type (75%), “lymphohistiocytic” (10%), “small cell” (8.3%), “giant cell” (3.3%), and “Hodgkin’s like” (3.3%). CD30-positive large anaplastic cells expressing the ALK protein both in the cytoplasm and nucleus represented the dominant tumor population in the common, Hodgkin’s-like and giant cell types, but they were present at a smaller percentage (often with a perivascular distribution) also in cases with lymphohistiocytic and small cell features. In this study, the ALKc antibody also allowed us to identify small neoplastic cells (usually CD30 negative) with nucleus-restricted ALK positivity that were, by definition, more evident in the small cell variant but were also found in cases with lymphohistiocytic, common, and “Hodgkin’s-like” features. These findings, which have not been previously emphasized, strongly suggest that the neoplastic lesion (the NPM-ALK gene) must be present both in the large anaplastic and small tumor cells, and that ALK-positive lymphomas lie on a spectrum, their position being defined by the ratio of small to large neoplastic cells. Notably, about 15% of all ALK-positive lymphomas (usually of the common or giant cell variant) showed a cytoplasm-restricted ALK positivity, which suggests that the ALK gene may have fused with a partner(s) other than NPM. From a diagnostic point of view, detection of the ALK protein was useful in distinguishing anaplastic large cell lymphoma cases of lymphohistiocytic and small cell variants from reactive conditions and other peripheral T-cell lymphoma subtypes, as well as for detecting a small number of tumor cells in lymphohemopoietic tissues. In conclusion, ALK positivity appears to define a clinicopathological entity with a T/null phenotype (“ALK lymphomas”), but one that shows a wider spectrum of morphological patterns than has been appreciated in the past.     

Creutzfeldt-Jakob disease (CJD) with a mutation at codon 148 of prion protein gene: relationship with sporadic CJD

Creutzfeldt-Jakob disease (CJD), the most common human prion disease, includes sporadic (s) and familial (f) forms. Regardless of etiology, both forms are thought to share the pathogenic mechanism whereby the cellular prion protein (PrP(C)) converts into its pathogenic isoform (PrP(Sc)). While PrP(C) conversion is thought to be random in sCJD, conversion in fCJD is facilitated by the congenital presence of mutated PrP. Differences in PrP genotype (PRNP) and in conversion circumstances lead to PrP(Sc) with distinct characteristics that elicit different disease phenotypes. Here, we describe a case of fCJD with a substitution of histidine (H) for arginine (R) at codon 148 (R148H) and heterozygosity of the methionine/valine (M/V) polymorphic codon 129, with the 129M allele coupled with the mutation. The disease phenotype and all major characteristics of PrP(Sc) of fCJD(R148H) were virtually indistinguishable from those of sCJDMV2, which has features different from those of any other sCJD. Therefore, despite the differences in etiology, PRNP, and conversion process, the two forms of PrP(Sc) had similar characteristics. Furthermore, comparison of fCJD(R148H) with a recently reported case carrying R148H and homozygosity at codon 129 suggests that codon 129 coupled with the mutation as well as that located on the normal allele can modify major phenotypic and PrP(Sc) features of fCJD(R148H).     

Direct detection of proviral gag segment of human immunodeficiency virus in peripheral blood lymphocytes by colorimetric PCR assay as a clinical laboratory tool applied to different at-risk populations.

We used a colorimetric polymerase chain reaction (PCR)-based assay in kit form to detect directly human immunodeficiency virus type 1 (HIV-1) proviral gag sequences in peripheral blood cells from 68 healthy blood donors, 51 subjects at risk for HIV infection, 122 patients with HIV-1 infection, 11 patients with indeterminate Western blot (immunoblot) results, 4 blood donors HIV-1 positive by enzyme immunoassay, and 13 children born to HIV-1-seropositive mothers. The results obtained in the blood donors and HIV-1-infected patients demonstrated the high degree of diagnostic specificity and sensitivity of the PCR method. HIV-1 infection was excluded in 10 of the 11 patients with indeterminate Western blot results and in all four enzyme immunoassay-positive blood donors. A diagnosis of HIV infection was ruled out by negative PCR results in 5 of 13 children from seropositive mothers, which excluded vertical transmission of the infection in these cases; these children were younger than 3 months and had positive serological results. Two at-risk patients with negative serological results had positive PCR results. All results were confirmed by conventional PCR. In conclusion, colorimetric PCR, which is commercially available in kit form, is an easy and reliable technique that can be used to detect proviral HIV-1 genomes in blood cells, and despite the limitations owing to HIV genome variability, it is useful in the clinical setting for the diagnosis of HIV infection in selected categories of patients.     

Sequence-Based analysis of the HLA-DRB1 polymorphism in Metalsa Berber and Chaouya Arabic-speaking groups from Morocco

To examine the genetic diversity in Morocco, the polymorphism at the HLA-DRB1 locus was investigated in two populations: the Metalsa group consisting of Berbers from north Morocco (who speak the Tarifit language and live in the Nador area), and the Chaouya group who are Arabic-speaking people from west Morocco (Atlantic coast) living in the Settat area. The DRB1 alleles of 197 healthy unrelated individuals were identified by direct DNA sequencing of exon 2 using fluorescently-labeled primers. A total of 28 and 29 alleles at DRB1 locus were identified in the Metalsa and Chaouya groups, respectively. The most frequent alleles in the Metalsa group are DRB1*03011 (20.2%), DRB1*0701 (12.12%), and DRB1*1302 (11.11%). In the Chaouya group, DRB1*0701 (16.33%), DRB1*15011 (12.76%), and DRB1*03011 (11.73%) are most common. Each population exhibits some specific variants and some uncommon alleles. The frequency of the DRB1*03011 allele differs significantly between the two populations (p = 0.0311). The DRB1 frequency distributions in the two groups suggest the effects of balancing selection. The interpopulation analysis highlighted a strong relatedness, based on genetic distances, between the two Moroccan groups and the other north Africans (the Moroccans from El Jadida area, Moroccan Souss Berbers, Algerians, and Tunisians), and to a lesser extent with the Iberians, French, and Ethiopians.     

Primary cutaneous large B-cell lymphoma of the leg: histogenetic analysis of a controversial clinicopathologic entity

This study analyzes the pathologic and molecular features of 5 cases of primary cutaneous large B-cell lymphoma of the leg (PCLBCL-leg), recently included in the European Organization for Research and Treatment of Cancer (EORTC) classification of primary cutaneous lymphoma. PCLBCL-leg accounts for 5% to 10% of all primary cutaneous B-cell lymphoma (PCBCL), usually affects elderly patients and carries a worse prognosis than other forms of PCBCL. It has been proposed that the malignant cells of PCLBCL-leg originate from germinal center (GC)-related cells, but their effective normal counterpart is unclear, and the rationale behind the inclusion of this lymphoma as a separate entity is based on its prognosis rather than on its proved histogenesis. All of our cases of PCLBCL-leg morphologically resembled diffuse large B-cell lymphoma (DLBCL), but to better define their histogenesis, we also analyzed various phenotypic and genotypic markers, including mutations of the Ig and of BCL-6 genes, as well as expression of the bcl-6, MUM1, and CD138/syndecan-1 proteins. Immunohistochemically, all of our cases stained for the L-26/CD20cy and CD79a antigens and expressed the bcl-2, bcl-6, and MUM-1 proteins but were negative for both the CD10/CALLA and CD138 antigens. With respect to molecular analysis, the lymphoma population of all PCLBCL-leg carried hypermutation of Ig genes, and all but 1 case also harbored mutations of the BCL-6 gene. Our results indicate that PCLBCL-leg are similar both under the morphofunctional and molecular profiles to most DLBCL of other sites. Thus, caution seems justified before definitely considering PCLBCL of the leg as a distinct entity.     

Tumor angiogenesis as a prognostic factor in thick cutaneous malignant melanoma

The prognostic value of the extent of neovascularization in cutaneous melanoma is a highly controversial issue. The aim of the current study was to evaluate whether the morphometric analysis of tumor vascularity may be helpful in predicting the clinical outcome of patients with thick cutaneous melanomas. A series of 15 patients with melanoma (>3 mm in thickness) who did not experience disease progression after long-term follow-up (10 years) and 30 matched controls who underwent recurrence and/or metastases were selected for the study. Microvessels were immunohistochemically stained with anti-CD31 antibody. Several parameters, including vessel number, vascular density, vessel area, equivalent circle diameter, perimeter, shape factor, compactness, and the number of vascular ramifications per 100 vessel sections, were quantitatively assessed by a computer-aided semi-automatic image analysis system. Mean vessel area was 341.69 microm2 in cases without progression and 512.55 microm2 in the progressed melanomas (P=0.008, Mann-Whitney U test). The mean equivalent circle diameter was 18.95 microm in non-progressed melanomas and 22.57 microm in progressed melanomas (P=0.009). The mean number of ramifications was 0.8 in cases without progression and 1.9 in the controls (P=0.03). Microvessel count and vascular density were higher in progressed cases (17.37 vs. 11.73 and 28.94/mm2 vs. 19.55/mm2, respectively), but the difference did not reach statistical significance (P=0.06). Our results suggest that neovascularization is a critical event in the progression of thick melanoma. Its prognostic significance is better assessed by quantification of vessel area, equivalent circle diameter, and microvessel branching, whereas microvessel count and vascular density do not provide significant prognostic information.     

BCL-6 protein expression in AIDS-related non-Hodgkin's lymphomas: inverse relationship with Epstein-Barr virus-encoded latent membrane protein-1 expression.

This study aimed at investigating the expression of the BCL-6 protein in acquired immune deficiency syndrome (AIDS)-related non-Hodgkin's lymphomas (AIDS-NHLs) and at comparing the expression pattern with the presence of Epstein-Barr virus (EBV) infection of the tumor clone. A total of 34 AIDS-NHL biopsies, including 16 AIDS-related diffuse large-cell lymphomas (AIDS-DLCLs) and 18 AIDS-related small-noncleaved-cell lymphomas (AIDS-SNCCLs) as well as 7 AIDS-SNCCL cell lines were immunostained with a BCL-6-specific monoclonal antibody. Expression of BCL-6 protein was detected in 9 of 16 AIDS-DLCLs, 18 of 18 AIDS-SNCCLs, and 3 of 7 AIDS-SNCCL cell lines. Expression of BCL-6 among AIDS-NHLs occurred independently of the presence of molecular lesions of the bcl-6 gene. Notably, among EBV-positive AIDS-NHL biopsies and cell lines, expression of BCL-6 was mutually exclusive with the expression of EBV-encoded transforming antigen latent membrane protein-1. The mutual exclusion between BCL-6 and latent membrane protein-1 expression was further confirmed by in vitro superinfection experiments of an AIDS-SNCCL cell line originally devoid of EBV sequences. Overall, the frequent association between AIDS-NHLs and expression of BCL-6, a protein selectively expressed by germinal center B cells, suggests that these lymphomas may originate from the germinal center.