Two different anti-erythroid monoclonal antibodies in immunodiagnosis of human leukemias: a comparative study

Reticulocyte analysis by flow cytometry and other techniques

Enumeration of peripheral blood reticulocytes is an essential part of the diagnosis and management of anemic patients, since the number of reticulocytes in the peripheral blood reflects the erythrocytic activity of the bone marrow. Reticulocyte enumeration using flow cytometric methodology is rapidly replacing the inaccurate, imprecise manual counting technique used in the past. This article explores the pathophysiology of the reticulocyte, the various means of counting reticulocytes, and the diverse clinical applications of reticulocyte data.

Antigen of erythroblast (Ag-Eb): a membrane protein that may be an erythroid-specific transferrin receptor

Only a limited number of erythroid cell surface markers have been described in the literature. Ag-Eb was originally described as an erythroid-specific cell surface glycoprotein and could be used as an erythroid differentiation marker, but more recent studies suggest this localization is more widespread. From the data summarized in this review, it is hypothesized that Ag-Eb is a member of a subset of the transferrin receptor family and that it functions together with these receptors in the uptake and metabolism of iron, particularly at histo-hematic barriers.

Reactivity of anti-macrophage monoclonal antibody D11 in human leukemia and malignant lymphoma

We have studied the reactivity patterns of a previously described pan-macrophage monoclonal antibody (MAb) D11 in 324 cases of acute leukemia and malignant lymphoma (ML). Reaction of D11 in tissue sections was restricted to histiocytes and macrophages. In non-Hodgkin's ML, D11 helped to confirm or to establish the histiocytic nature in 8 of 96 cases, i.e., in 4 of 6 histiocytic MLs; 2 of 13 anaplastic large-cell lymphomas; 1 of 4 large-cell immunoblastic clear-cell MLs; and 1 of 2 histiocytosis X cases. Positive reaction of D11 in acute lymphoblastic leukaemia (ALL) was found in 9 of 86 cases (all belonging to early B-lineage leukemia), of which 4 were CD34-positive and 5 co-expressed 1 or more myeloid/monocytic antigens. MAb D11 did not react in 42 cases of acute-myeloblastic-leukemia (AML) FAB variants M0-M5, except 1 acute mixed-lineage leukemia M1/pre-pre-B. Comparative study of the MAb D11 and a standard CD68 MAb KP- 1 showed that the antigens belong to different epitopes of different molecules.

Expression of erythroblast antigen (AG-EB) in hematopoietic and non-hematopoietic mouse cells during pre- and postnatal ontogenesis. Immunocytochemical study using monoclonal antibody

It has been shown previously that erythroblast antigen (AG-EB) is an interspecies antigen expressed on the surface of nucleated red cells and reticulocytes. We have recently produced the monoclonal antibody MAE 15 that reacted specifically with murine epitope of AG-EB. Using MAE15 and immunocytochemical techniques on the light and electron microscopic levels the expression of AG-EB was studied in mouse embryonal and adult tissues. In mouse embryos AG-EB was revealed in erythroid cells of the yolk sac, liver and spleen, in epithelial cells of the intestine, salivary and thyroid glands as well as in the skin. The adult pregnant mice displayed AG-EB in cells of the yolk sac, decidua and trophoblast. The normal adult mice definitely expressed AG-EB not only in nucleated erythroid cells of the bone marrow and spleen but also in cells of non-hemopoietic organs and tissues: in epithelium of intestine, some glands and tubules of the kidney and testis; in endothelium of blood brain capillaries; in cells of the glandular layer of the epidermis; in insertion disks of myofibrils. Our findings suggest a possible transport role of AG-EB in different "barrier" cells.

Blast cells in child and adult AML: comparative study of morphocytochemical, immunological and cytogenetic characteristics

Bone marrow blast cells of 174 child and 188 adult patients with AML were examined and characterized in terms of their FAB type, immunological phenotype (102 children, 123 adults) and karyotype (69 children, 95 adults). The incidence of FAB variants of AML proved similar in children and adults. In patients under 15 and over 60, peroxidase activity in myeloblasts was lower than in middle-aged patients. Similar rates of HLA-Dr. Thy-1, CD11a, T-cell antigens, CD19, Gly-A and Eb antigens were found in cells of child and adult patients. The frequency of CD11b, CD38 and CD10 antigen expression on blast cells was higher in children than in adults. Abnormal blast karyotype was noted in 81.8% of children and 73.7% of adults. Translocation (8;21) was usually found in cases of M2 type (82%), significantly more frequently in children. predominantly in the group aged 6-10. t(15;17) was detected in all age groups only in M3 type of cells (86%). t(9;22) occurred more frequently in adults than in children; t(11q23) incidence rates were somewhat higher in children than in adults. Three cases of AML in children are described with deletion of chromosome 5 in their leukaemic cells. The data obtained indicate different biological characteristics of blast cells in children and adults. It is likely that haemopoietic cell involvement in children under 2 years and adult patients over 60 occurs at earlier stages than in middle-aged patients.

Cytotoxic effect of ricin A-chain conjugates containing monoclonal antibodies against human erythroid cells

Selective elimination of human erythroblastoid cells by the conjugate of the A-chain of a plant toxin ricin (RA) and monoclonal antibody (MAb) HAE9 (IgM) directed against human erythroblast antigen (Ag-Eb) has been demonstrated. In comparative experiments, MAb HAE3 (IgM) against human glycophorin-A was used. On average, the conjugates obtained contained two A-chain molecules and one antibody molecule. Efficiency of cytotoxic action of native ricin and conjugates was compared both with the amount of binding sites on the surface of K562 cells and the internalization rate of these proteins. The association constants of the proteins proved to be almost the same (ka = 10(8) M-1). The ID50 values were 1.1 x 10(-11), 3.2 x 10(-10) and 3.1 x 10(-9) M for ricin, HAE9/RA and HAE3/RA, respectively. Ammonium chloride at a concentration of 10 mM increases the cytotoxic effect of the HAE9/RA conjugate approximately 10 times and does not change the activity of the HAE3/RA conjugate.

Heterogeneity of peripheral blood reticulocytes: a flow cytometric analysis with monoclonal antibody HAE9 and thiazole orange

The expression of a human erythroid cell surface antigen recognized by monoclonal antibody (mAB) HAE9 has been studied on peripheral blood reticulocytes by one- and two-color flow cytometry. Total reticulocyte count was determined using Thiazole Orange (TO) and flow cytometry. In normal individuals, 4.56% of reticulocytes were stained by FITC-labeled mAB HAE9. The correlation between reticulocyte percentage by TO and HAE9 staining was 0.828 (P less than 0.0001) in patients with hematocrits less than 0.25. A HAE9-positive reticulocyte percentage of 6-44% was observed when analyzed by two-color flow cytometry with TO and mAB HAE9. These findings, in conjunction with previous studies, suggest that mAB HAE9 recognizes an early, less differentiated population of peripheral blood reticulocytes. Enumeration of immature reticulocytes may be of clinical utility.