Results of immunophenotypic examinations of peripheral blood and/or bone marrow (BM), involved in low-grade B-cell non-Hodgkin's lymphomas, were compared with the results of cytomorphological and histopathological examinations in 133 adult patients. 69 cases of chronic B-lymphocytic leukaemia (B-CLL), 16 centrocytic (CC) lymphomas, 14 centroblastic-centrocytic (CB/CC) lymphomas, 15 immunocytomas (IC), 10 cases of hairy cell leukaemia (HCL), four prolymphocytic leukaemias (PLL), two B-CLL in transformation, one splenic lymphoma with villous lymphocytes (SLVL), one hairy cell leukaemia variant (HCL-V), and one lymphocytic lymphoma (LC) were classified according to the Kiel and/or FAB classification. Leukaemic disease was found in 105 cases. The following markers were used for immunocytology (APAAP technique) of blood and/or BM smears: CD19, CD5, CD10, CD11c, CD14, CD21, CD22, CD23, CD25, CD38 and TdT. All cases tested showed CD19, but no TdT expression. Every case of HCL had a distinct phenotype with expression of CD11c, CD22 and CD25 and the lack of CD5 and CD23 antigens. In all other NHL cases a very heterogenous expression of CD-antigens with no significant correlations to the cytomorphological subtypes was found. The expression of CD5 is a frequent but inconstant finding in lymphoproliferative diseases other than B-CLL, so 50% of CB/CC, 75% of CC and 80% of IC were CD5 positive. Our results indicate that, with the exception of HCL, the diagnostic relevance of immunophenotyping for the classification of cytomorphologically and histopathologically defined subtypes in blood and/or BM is of very limited value.

Sequence data of the small subunit rRNA (SSU-rRNA) gene were used to identify Septata intestinalis in biopsies of human immunodeficiency virus-infected patients by polymerase chain reaction (PCR), southern blot hybridization, cloning, and comparative genetic sequencing. DNA products of correct size could be amplified from all examined tissues with S. intestinalis infection but also from 2 biopsies with Enterocytozoon bieneusi and from 1 biopsy with Encephalitozoon cuniculi infection. Southern blot hybridization with an S. intestinalis-specific probe and partial sequencing of the DNA fragments showed high homology with published S. intestinalis sequences and confirmed that the amplified PCR products really derived from the SSU-rRNA gene of S. intestinalis. PCR testing can detect very light infections with S. intestinalis. Thus, S. intestinalis seems to occur more frequently in the form of latent infections and the true prevalence of the parasites may be much higher than previously reported.

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