Chlamydiae in febrile children with respiratory tract symptoms and age-matched controls, Ghana.

Members of the Chlamydiales order are obligate intracellular pathogens causing acute and chronic infectious diseases. Chlamydiaceae are established agents of community- and zoonotically acquired respiratory tract infections, and emerging pathogens among the Chlamydia-related bacteria have been implicated in airway infections. The role of both in airway infections in Africa is underexplored. We performed a case -control study on the prevalence of Chlamydiaceae and Chlamydia-related emerging pathogens in children with febrile respiratory tract infections in West Africa, Ghana. Using a pan-Chlamydiales broad-range real-time PCR, we detected chlamydial DNA in 11 (1.9%) of 572 hospitalized febrile children with respiratory tract symptoms and in 24 (4.3%) of 560 asymptomatic age-matched controls (p 0.03). Chlamydiaceae were found to be common among both symptomatic and healthy Ghanaian children, with Chlamydia pneumoniae being the most prevalent species. Parachlamydiaceae were detected in two children without symptoms but not in the symptomatic group. We identified neither Chlamydia psittaci nor Simkania negevensis but a member of a new chlamydial family that shared 90.2% sequence identity with the 16S rRNA gene of the zoonotic pathogen Chlamydia pecorum. In addition, we found a new Chlamydia-related species that belonged to a novel family sharing 91.3% 16S rRNA sequence identity with Candidatus Syngnamydia venezia. The prevalence and spectrum of chlamydial species differed from previous results obtained from children of other geographic regions and our study indicates that both, Chlamydiaceae and Chlamydia-related bacteria, are not clearly linked to clinical symptoms in Ghanaian children.

Single-cell analysis of T-cell receptor-gamma rearrangements in large-cell anaplastic lymphoma.

Large-cell anaplastic lymphomas (LCAL) are characterized by their distinctive morphology together with expression of the CD30 antigen. In addition, a chromosomal translocation, t(2;5) (p23; q35), can be detected in most cases. A significant proportion of LCALs carry rearrangements of the T-cell receptor-gamma (TCR-gamma) locus and display a T-cell phenotype. In about a third of the cases, another type of non-Hodgkin-lymphoma precedes LCAL. Early transformations of non-Hodgkin's lymphoma into LCAL might escape clinical detection in a significant number of cases. The existence of clonally related lymphoid cells within the lymph node infiltrates must be claimed in these cases. Recently, a small-cell-predominant variant of LCAL was described in which only few large tumor cells expressing the CD30 antigen are found together with numerous small lymphocytes, which are frequently CD30-. This observation in particular prompted us to investigate the clonal relationship of the tumor cell compartment and admixed small lymphocytes in one case of common LCAL with T-cell genotype. For this purpose, we chose to amplify rearranged TCR-gamma sequences from single cells isolated from immunostained frozen sections by using a micromanipulator. A total of 119 cells were investigated. Amplification products were obtained in 17 of 79 CD3+ cells, 12 of 30 CD30+ cells, and three of 10 CD20+ cells. The nucleotide sequences were determined in 28 cells by nonradioactive sequencing. In 11 CD30+ cells, the predominant rearrangement of TCR-gamma was identified. No clonal diversity was observed. The small CD3+ lymphocytes were unrelated to the anaplastic CD30+ tumor cells. This report describes a method to analyze rearrangements of the TCR-gamma in single cells isolated from immunostained frozen sections. Application of this technique revealed an absence of clonal diversity in a case of LCAL and documented the polyclonal nature of admixed small CD3+ lymphocytes.

Detection of T-cell clonality in paraffin-embedded tissues.

In lymph node diagnosis, difficulties are frequently encountered with the differential diagnosis of reactive and neoplastic T-cell proliferations. Immunohistochemistry is of limited use, and fresh frozen material for DNA studies is not available in many cases. We have established a polymerase chain reaction (PCR) technique to amplify rearranged T-cell receptor (TCR)-gamma sequences from paraffin-embedded material. Our method differs from other techniques previously described in that it uses four sets of family-specific variable (V)gamma primers. Clonality of the investigated T cells is reflected not only by the varying lengths of amplified products but also by differences in the relative amount of rearranged V gamma families. Preliminary studies indicate that this approach can provide information about the presence of predominant T-cell clones within the sample and thus help to classify the lymph node lesion. With this technique we were able to confirm clonality in seven of 12 T-cell lymphomas in paraffin-embedded tissues.

[Bcl-2 in potentials precursors of nodular paragranuloma and its dedifferentiated variant (large cell B-lymphoma)]. / Bcl-2 in möglichen Vorstadien des nodulären Paragranuloms und seiner entdifferenzierten Variante (grosszelliges B-Zell-Lymphom).

We have investigated seven cases of large cell lymphomas (LCL) developing simultaneously or metachronously to nodular lymphocyte-predominant Hodgkin's disease (nodular paragranuloma, NP) for the presence of EBV and the chromosomal translocation t(14;18) by use of the polymerase chain reaction (PCR). The expression of the bcl-2 oncogene product in these cases and in five cases of progressive transformation of germinal centres as a potential precursor of NP was detected immunohistochemically with the monoclonal antibodies bcl-2-100 and bcl-2-124. All cases investigated were negative for EBV genomic material. The chromosomal translocation t(14;18) was also absent. Expression of the bcl-2 oncogene could be detected only in one case of nodular paragranuloma and in an unrelated case of LCL. Hence, LCL developing out of NP differ from other germinal center derived high-grade lymphomas.