A hypogranular variant of acute promyelocytic leukaemia showing a heterogenic immunophenotype with CD34, CD2, HLA-DR positivity: a case report and review of the literature.

We report the case of a 46-year-old man who presented with the hypogranular variant of an acute promyelocytic leukaemia (APL). RT-PCR analysis for detection of the t(15;17) fusion transcript confirmed the cytological findings by demonstrating a bcr-3 type PML/RARalpha rearrangement. According to the WHO-classification, this leukaemia fulfilled the criteria for 'Acute promyelocytic leukaemia with t(15;17)(q22;q12)'(1). Immunophenotyping revealed a leukaemic population with an aberrant expression of markers. Besides the presence of the expected immunophenotypic markers in APL (CD45 with low density, CD13+, CD33+, CD15-, CD117+ and MPO+), the population showed a positivity for CD34, CD2 and HLA-DR for at least a part of the malignant promyelocytes. Since the expression of these three markers, all together, is rather unique, we reviewed the literature to prove the relationship of this specific immunophenotype with morphology, clinical and molecular findings.

Increased monocyte transcription of the proteinase 3 gene in small vessel vasculitis.

Proteinase 3 (PR3) is a pleiotropic and destructive serine protease and it is also a major target for autoantibodies in systemic small vessel vasculitis. We have shown recently that patients in stable remission have increased circulating levels of PR3, independent of autoantibody titre, inflammation, neutrophil degranulation and renal function. Here we explore the possibility of increased PR3 gene transcription. RNA was purified from peripheral blood monocytes from vasculitis patients and controls. Specific mRNA was measured by TaqMan real-time polymerase chain reaction (PCR). The monocyte-like cell lines THP-1 and U937 and human peripheral blod monocytes from healthy controls were stimulated with cytokines and lipopolysaccharide (LPS) for different time periods. PR3 protein was measured in plasma with enzyme-linked immunosorbent assay (ELISA). The median result for PR3 mRNA was 9.6 (1.8-680) for 22 patients, compared to 1 (0.1-2.8) for the 15 healthy controls. Elastase expression was also significantly increased, whereas myeloperoxidase and interleukin-8 were not. Stimulation of monocytes with tumour necrosis factor (TNF)-alpha, interferon (IFN)-gamma or LPS did not result in any increase of PR3 or elastase transcription, whereas interleukin (IL)-8 transcription was increased 10-fold. Circulating monocytes from patients with systemic vasculitis display increased PR3 gene transcription compared to healthy controls and patients with sytemic lupus erythematosus (SLE). This may be important for the development of vasculitis. Our results do not favour a role for cytokines, antineutrophil cytoplasmic antibodies (ANCA) or immunosuppressive medication in the upregulation of PR3 transcription in vasculitis.

The - 564 A/G polymorphism in the promoter region of the proteinase 3 gene associated with Wegener's granulomatosis does not increase the promoter activity.

Proteinase 3 is the major autoantigen in patients with Wegener's granulomatosis. Earlier studies have shown that circulating leucocytes from patients with Wegener's granulomatosis show elevated proteinase 3 surface expression and mRNA levels. Wegener's granulomatosis patients also have increased levels of proteinase 3 in plasma. A single nucleotide polymorphism (SNP) (-564 A/G SNP) in the promoter region has been associated with disease. This SNP introduces a new potential Sp1 transcription factor binding site that may be responsible for the observed up-regulated expression of proteinase 3. To investigate this a 740 base pair long region of the promoter was cloned from genomic DNA. The disease-associated -564 A/G, as well as a control -621 A/G exchange, were introduced by polymerase chain reaction mutagenesis and cloned into a luciferase reporter vector. Endogenous expression levels of proteinase 3 mRNA and promoter activity of the cloned constructs were measured in three myeloid cell lines, HL-60, U937 and NB-4, and in epithelial HeLa cells. The results demonstrate a good correlation between the endogenous proteinase 3 mRNA expression and the promoter activity, as judged by luciferase activity. However, no significant differences in activity between the wild-type, polymorphic and the mutated control variant were found. In conclusion, the -564 A/G polymorphism is not responsible for the increased expression levels seen in myeloid cells from patients with Wegener's granulomatosis.