Prevalence and clinical correlations of MLL gene rearrangements in AML- M4/5

Rearrangements of the human trithorax gene (MLL, HRX, Htrx-1, All-1) were studied by Southern blotting in blast cells stored at presentation from 65 adults with de novo acute myelomonocytic (AML-M4) and acute monocytic leukemia (AML-M5). MLL rearrangements were demonstrated in 15 (23%) cases, including eight patients in whom karyotype analysis had failed to detect abnormalities of chromosome band 11q23. The patients with MLL rearrangements did not differ significantly from those with germline configurations in terms of the sex and age of the patients, the presence of lymphadenopathy, hepatosplenomegaly, or central nervous system involvement, and the absolute blast count at diagnosis. Kaplan- Meier analysis of the treated patients demonstrated no difference in survival for patients with MLL rearrangements compared with those without rearrangements. Therefore, in contrast to infantile acute leukemia, in adults with AML-M4 and AML-M5, MLL rearrangements do not identify a subgroup of patients with different clinical features or prognosis.     

Erythrocyte-endothelial cell adherence in sickle cell disorders

Detachment of individual sickle erythrocytes from cultured endothelial cell monolayers has been evaluated by a fluid-shearing technique in an effort to quantitate adherence at shear forces that would be anticipated in the in vivo circulation. Nonirreversibly sickled cells (non-ISC) were more adherent at normal oxygen tensions than control cells. More than 1% non-ISC remained attached to the monolayer at forces greater than physiologic shear stresses in capillary and venous circulations, and many of the most avidly attached cells, once separated, immediately reattached to adjacent endothelial cells. These data suggest that hemoglobin S-containing erythrocytes may have a higher frequency of adherence in vivo in regions of low shear stress where prolonged erythrocyte-endothelial cell contact could occur. Some of these cells detached by shear force would subsequently reattach in in vivo conditions. Plasma-enhanced attachment frequency and plasma from blood in a case of sickle crisis caused further increase. These observations further support the concept that sickle erythrocyte- endothelial cell interaction may be a significant factor in initiation of vascular occlusive events in sickle cell disease.     

Detecting fetomaternal hemorrhage: a comparison of five methods

Appropriate postpartum administration of Rh immune globulin relies on sensitive detection and accurate quantitation of fetomaternal hemorrhage (FMH). Recently, the microscopic Du test (micro Du) enhanced with polyethylene glycol (PEG Du) and flow cytometry (FC) have been advocated for this purpose. Three qualitative methods (micro Du, rosette test, and PEG Du) and two quantitative methods (acid elution and FC) for assessing FMH were evaluated with particular attention given to PEG Du and FC. In vitro studies comprised 10 series of dilutions of D+ cord cells in D- adult cells to yield D+ cell concentrations of 0.06, 0.12, 0.25, 0.50, 0.75, 1.0, and 2.0 percent. Additionally, 26 postpartum samples were tested. Of the qualitative techniques, the micro Du test was the least sensitive with 20 percent false-negative results occurring at 0.5 percent fetal cells. The PEG Du test was only slightly more sensitive and offered no clinical advantage. The rosette test was the most sensitive, consistently detecting fetal cells at concentrations of 0.25 percent or greater. FC and acid elution showed similar results, with good correlation obtained between measured and expected quantities of fetal cells (r = 0.99 and 0.96, respectively). One of 26 postpartum samples was positive by all screening techniques; acid elution and FC detected 0.3-percent concentrations of fetal cells and 0.17-percent concentrations of D+ cells, respectively. Although acid elution is a more commonly used method for quantitating FMH, FC offers an acceptable alternative that is capable of analyzing large numbers of cells with objectivity and reproducibility.     

Prognostic discrimination in "good-risk" chronic granulocytic leukemia

The prognostic significance of disease features recorded at the time of diagnosis was examined among 813 patients with Philadelphia chromosome- positive, nonblastic chronic granulocytic leukemia (CGL) collected from six European and American series. The survival pattern for this population was typical of "good-risk" patients, and median survival was 47 mo. There were multiple interrelationships among different disease features, which led to highly significant correlations with survival for some that had no primary prognostic significance, such as hematocrit. Multivariable regression analysis indicated that spleen size and the percentage of circulating blasts were the most important prognostic indicators. These features, and age, behaved as continuous variables with progressively unfavorable import at higher values. The platelet count did not influence survival significantly at values below 700 X 10(9)/liter but was increasingly unfavorable above this level. Basophils plus eosinophils over 15%, more than 5% marrow blasts, and karyotypic abnormalities in addition to the Ph1 were also significant unfavorable signs. The Cox model, generated with four variables representing percent blasts, spleen size, platelet count, and age, provided a useful representation of risk status in this population, with good fit between predicted and observed survival over more than a twofold survival range. A hazard function derived from half of the patient population successfully segregated the remainder into three groups with significantly different survival patterns. We conclude that it should be possible to identify a lower risk group of patients with a 2-yr survival of 90%, subsequent risk averaging somewhat less than 20%/yr and median survival of 5 yr, an intermediate group, and a high- risk group with a 2-yr survival of 65%, followed by a death rate of about 35%/yr and median survival of 2.5 yr.     

Characterization of B-cell leukemias: a tentative immunomorphological scheme

Analysis of the morphological and immunologic [surface (Sm Ig) and cytoplasmic (Cy Ig) immunoglobulin, faintness (f.imfl) or brightness (b.imfl) of surface immunofluorescence, rosette formation with mouse erythrocytes (MR), or sheep red cells coated with C3 (EAC)] characteristics of the neoplastic lymphocytes involved in 137 cases of B-cell leukemias allowed the differentiation of the following cytologic categories: B1 small lymphocytes (71); SM Ig+, f.imfl., Cy Ig-, MR+, EAC+; B2 prolymphocyte (4): SM Ig+, b.imfl., Cy Ig-, MR+, EAC+. B3 plasmacytoid lymphocyte (2): Sm Ig+, b.imfl., Cy Ig+/-, MR+!-, EAC+/- B4 small cleaved lymphocyte (23): Sm Ig+, b.imfl., Cy Ig-, MR-, EAC+. B5a large cleaved and B5b noncleaved lymphocytes (14): Sm Ig+, b.imfl., Cy Ig-, MR-, EAC-. B6 small noncleaved "Burkitt-like" lymphocyte (5): Sm Ig+, b.imfl., Cy Ig-, MR-, EAC-. B7 plasma cell (2): Sm Ig+, MR-, EAC-. B8 hairy cell (16): Sm Ig+, b.imfl., Cy Ig-, MR-, EAC-, also exhibiting ingestion or attachment of particulate material, not seen in other types. Improved delineation of the heterogeneous group of B-cell leukemias might be of developmental significance in lymphocyte differentiation and improve current prognostic and therapeutic criteria.     

Evaluation of inosin-5'-monophosphate dehydrogenase activity during maintenance therapy with tacrolimus

Objectives: The aim of this study was to identify a target range for inosin‐5′‐monophosphate dehydrogenase (IMPDH) activity in maintenance therapy with tacrolimus (TCL), and to apply the measurement of IMPDH activity to the therapeutic drug monitoring for mycophenolate mofetil (MMF). Methods: Eleven patients with renal transplants and 10 healthy volunteers were investigated. All patients were treated with a combination of TCL, steroid and MMF for 2 months after transplantation, and were in stable and good condition. IMPDH activity was determined indirectly by measuring xanthosine 5′‐monophophate in cell lysates supplemented with IMP and β‐nicotine adenine dinucleotide using an high‐performance liquid chromatography (HPLC) method. Results: The within‐run reproducibility of the assay was excellent, with relative standard deviation (RSD) values of 0·41–4·08%. The mean differences between the spiked concentrations of xanthosine 5′‐monophophate and their real values (mean relative errors; MREs) were within a range of 2·66–8·89%, showing good accuracy. The interday RSD values were 1·51–6·12% and MREs ranged from 2·10% to 8·89%. Cell lysates showed a 5–6 nmol/L IC₅₀ mycophenolic acid (MPA) concentration. TCL, cyclosporine and prednisolone did not affect IMPDH activity. The peak MPA concentration was achieved at 1 h after dosing. IMPDH activity decreased to 75% and 67% at 1 and 2 h after dosing respectively. Therefore, the inhibition rates of MPA against IMPDH activity may be adequate at 25–40% in TCL maintenance therapy. Conclusion: Inosin‐5′‐monophosphate dehydrogenase activity in cell lysates could be reliably determined by HPLC. A 25–40% inhibition of IMPDH activity may be an appropriate range for preventing rejection with MPF but this requires further validation using larger studies with harder outcomes such as rejection episodes.