Fas/APO-1 (CD95) expression in myelodysplastic syndromes.

Increased apoptosis of myeloid precursors appears to contribute to the pathophysiology of cytopenias in myelodysplastic syndromes (MDS). Fas /APO-1(CD95) is a cell surface protein inducing an apoptotic signal after its binding to Fas ligand or to a functional anti-Fas antibody. Here we studied Fas expression by immunocytochemistry on marrow slides from 30 cases of MDS. Increased Fas expression in erythroblasts and/or immature granulocytes, compared to controls, was seen in 12 (40%) of the cases. In addition, in 16 of the 18 cases with > or = 5% marrow blasts, a variable proportion of blasts expressed Fas. Increased apoptosis was found by morphological analysis and/or TUNEL technique in marrow cells from 8 of the 26 cases analyzed (31%) The ability of Fas antigen to trigger apoptosis was studied after addition of a functional anti Fas antibody in 5 of the patients with Fas overexpression. Addition of this antibody, however, only lead to mild increase of apoptosis in immature granulocytes (but not other myeloid cells) in 2 of the 5 cases. Thus, increased Fas expression is seen in myeloid and/or blast cells in the majority of MDS cases. However, the relationship between this finding and increased apoptosis in MDS still remains to be established.

CD19 and immunophenotype of bone marrow plasma cells in monoclonal gammopathy of undetermined significance.

AIMS: To determine whether a particular phenotype or antigen is preferentially related to monoclonal gammopathies of undetermined significance (MGUS). METHODS: Bone marrow specimens from 56 patients with MGUS were stained immunocytochemically (ABC peroxidase) for CD38, CD56, CD9, CD10, CD19, CD20, CD22, and MB2. Specimens from patients recently diagnosed with multiple myeloma and reactive bone marrow samples were studied in parallel. RESULTS: CD38 was expressed on all plasma cells from all MGUS samples tested, while 36% were positive for CD56, CD9 and MB2 were both expressed strongly; CD20 was moderately expressed, and staining for CD10 and CD22 was uncommon. For these five B cell antigens there was no clear difference between their expression in MGUS and in multiple myeloma. A great difference was found for CD19: in MGUS this antigen was expressed on 2-91% of plasma cells (mean 35%) and 77% patients had > 10% positive plasma cells; in multiple myeloma its expression was low and only 12% patients had > 10% positive plasma cells. When these results were converted to numbers of CD19 positive plasma cells per 100 nucleated bone marrow cells, reactive bone marrow and MGUS specimens had a similar number of positive plasma cells. There was no correlation between expression of any of the antigens tested. CONCLUSIONS: Many of the so-called pre-B, B or activation antigens are present on plasma cells from MGUS specimens, and expression of CD9, CD10, CD20, CD22, MB2, and CD38 in MGUS was very similar to that in multiple myeloma. CD56 was frequently expressed in MGUS. In this series CD19 was highly expressed in MGUS but not in multiple myeloma. Plasma cells bearing this antigen could represent the non-neoplastic process and determination of its expression could be useful for the diagnosis of MGUS.

Immunological detection of myeloperoxidase in poorly differentiated acute leukemia.

We performed immunocytochemical detection of myeloperoxidase (MPO), using monoclonal antibody MPO-7, in 15 consecutive cases of adult acute leukemia (AL) unclassified by conventional cytological and cytochemical criteria and 7 AML-M1 with less than 10% of cytochemically MPO-positive blasts. In AL with negative MPO cytochemistry the anti-MPO reaction was positive in 5 of the 15 patients with 3, 3, 7, 11 and 45% positive blasts respectively. In AML-M1, immunocytochemistry was positive in a larger percentage of blasts than cytochemistry in 2 cases. Immunological detection of myeloid surface markers was positive in all 15 cases of unclassified AL (including the 10 AL with negative anti-MPO reaction). Eleven of the 22 patients from this study had mixed lymphoid-myeloid phenotype. Discrepancy between immunological MPO detection and light cytochemistry was more frequent in patients with mixed immunophenotype than in patients without lymphoid markers. No relationship between MPO-antigen positivity and clinical or biological features was seen. These findings confirm immunological detection of MPO as useful for the diagnosis of poorly differentiated AL. The high incidence of inactive MPO detectable only by immunocytochemistry in mixed lineage AL needs to be confirmed.

Filterability in children.

The filterability of total blood and erythrocytes has been investigated in 36 children from 2 to 14 years old by the filtration method developed by Reid. Red blood cells being obtained by centrifugation, were washed three times and resuspended in saline. Filterability was recorded as the filtration time of 1 ml of total blood or red cells suspension. The filtration time of total blood was: 49.10 +/- 14.5 s/ml; that of resuspended cells was: 18.19 +/- 6.16 s/ml. These results have been correlated with age, fibrinogen, white blood cells, glycaemia, haematocrit, and compared with the results obtained in 42 adults whose filtration times were: 33.04 +/- 7.40; and red cells' time: 13.99 +/- 2.95. Statistical analysis shows that the difference is very significant and not correlated with the investigated factors. Erythrocyte filterability may be influenced by still unknown factor.