The incidence of pseudothrombocytopenia in automatic blood analyzers.

UNLABELLED: The aim of the present work was to undertake an assessment of the incidence of pseudothrombocytopenia (PTCP) in patients referred for evaluation of thrombocytopenia in an outpatient hematology clinic. METHODS: Prospective assessment of 60 consecutive cases with platelet count < 100 x 10(9)/l in a hematology clinic during a 2-year period. RESULTS: PTCP was the second most common cause for low platelet count, with an incidence of 17%. Platelet count of patients with PTCP at presentation was 42 +/- 22 x 10(9)/l, and when re-analyzed on fresh samples, 208 +/- 39 x 10(9)/l. The relatively high prevalence of pseudothrombocytopenia in our series was due to a lack of microscopic inspection of the blood smear in the primary care laboratories and considerable delay in sample processing. CONCLUSIONS: PTCP should be considered in the assessment of low platelet count. While decreasing the transfer time of blood specimens may decrease PTCP incidence, microscopic inspection of the blood smear may avoid erroneous diagnosis of thrombocytopenia.

Spectral morphometric characterization of B-CLL cells versus normal small lymphocytes.

Spectral morphometric characterization of typical chronic lymphocytic leukemia (B-CLL) cells vs normal small lymphocytes stained by May-Grunwald-Giemsa was carried out by multipixel spectral imaging. The light intensity (450-850 nm of 10(4) pixels) from nuclear domains of each stained cell was recorded and represented as light transmittance spectra and optical density. Transmitted light spectra of two nuclear domains were determined, one with low-intensity light transmittance (LIT) and the other with high-intensity light transmittance (HIT). A spectral library was constructed using the four transmitted light spectra representing the HIT and LIT domains of the normal human lymphocytes and the LIT and HIT domains of the CLL cells. The spectral library served to scan CLL lymphocytes from 10 cases of CLL and the lymphocytes of 10 healthy individuals. Each spectrally similar domain in the nuclei of the lymphocytes was assigned an arbitrary color. The morphometric analysis of the spectrally classified nuclei showed specific spectral patterns for B-CLL in 92% of the cells. The specific spectral characteristics of each of the two cell populations were also observed by their optical density light absorbance spectra. We propose that spectral morphometric analysis may serve as an additional diagnostic tool for detection of CLL lymphocytes in a hematological specimen.

Ultrastructural observations on bone marrow cells of 26 patients with myelodysplastic syndromes.

Bone marrow aspirates from 26 patients with myelodysplastic syndrome (MDS) were examined using transmission electron microscopy. The red blood cell precursors in 9 patients showed varying degrees of dyserythropoiesis including the presence of 2 or more nuclei, nuclei with bizarre shape and iron deposits in the mitochondria. The myeloid series showed a tendency to hypogranulation (5 patients) and in 2 patients there were signs of platelet phagocytosis. The monocytes had a normal ultrastructure except for one patient with chronic myelomonocytic leukemia (CMML) with transformation to acute myelo-monocytic leukemia (AMML). In this case, the monocytes were immature, with markedly convoluted nuclei and scanty heterochromatin. The lymphocytes also had a normal appearance, except for one patient in whom the lymphocytes were immature, with lobulated nuclei and suggested transformation of MDS to acute lymphoblastic leukemia. The plasma cells in 3 patients were slightly increased in number and in one of them Russell bodies were seen both in the cytoplasm and the nucleus. The megakaryocytic series showed a shift to the left and in one patient there were signs of emperipolesis. The alterations in the hematopoietic cells in patients with MDS described in the present study indicate that the electron microscope may supplement light microscopic findings and help in the establishment of a correct diagnosis. This may be also evident in those cases of MDS in which the very early stages of leukemic transformation cannot be easily detected by light microscopy.

[Resistance to activated protein C--a novel cause of thrombophilia].

A point mutation in coagulation factor V which causes resistance to cleavage of factor Va by activated protein C (APC), was recently found to underlie thrombotic events. We examined 20 consecutive patients, under the age of 40, who suffered from idiopathic venous or arterial thrombosis. In 8 (40%) there was resistance to APC manifested by absence of the expected prolongation of activated partial thromboplastin time (aPTT). In 3, the addition of normal plasma corrected the anomaly in the patient's plasma, although the addition of factor V- deficient plasma caused no change. In a family of a 17-year-old boy with idiopathic deep venous thrombosis we found a mutation in factor V which was responsible for APC resistance. The patient and 4 family members showed a single G to A transition in position 1691 in their cDNA, resulting in substitution of arginine (506) for glutamine. The mutation in this area, which is the cleavage site for APC, is associated with thrombotic episodes and is frequently observed in patients with familial thrombophilia.

Restoration of in vitro hematopoiesis in B-chronic lymphocytic leukemia by antibodies to tumor necrosis factor.

Hematopoiesis was evaluated in 15 B-CLL patients using the mixed colony formation assay. The mean growth of all types of colonies in B-CLL peripheral blood was significantly lower than that of 10 normal controls (p less than 0.05). To investigate whether TNF is the cytokine involved in the reduced growth of hematopoietic progenitors in B-CLL, neutralizing anti-TNF antibodies (anti-TNF Abs) were added to the cultures. Anti-TNF Abs optimized in vitro hematopoiesis in 11 out of 15 B-CLL patients and a significant growth increase in all types of colonies was noted as compared to baseline cultures (p less than 0.05). In patients with stage IV disease, the increase in both mixed and erythroid colonies was more prominent than in patients with earlier disease stages. This optimization of growth was also observed in normal control cultures containing accessory cells. However, high TNF levels were measured in conditioned media from CLL patients and suppressed normal bone marrow hematopoietic progenitors growth. In contrast no TNF was detected in normal conditioned media. It is concluded that TNF and other cytokines, among them IL-3, play a role in the regulation of hematopoietic function in some B-CLL cases. These findings may have clinical applicability.

Felty's syndrome without concomitant arthritis: a variant.

A young female patient who had documented seropositive rheumatoid arthritis and was treated consecutively with aspirin, diclofenac, and gold salts was admitted years later for severe neutropenia. On examination she had, in addition, fever, positive rheumatoid factor, reversible swan-neck deformity of the fingers but otherwise normal joint findings. The patient responded to prednisone therapy. This case would appear to be a most unusual variant of Felty's syndrome.