Esterase Isoenzyme Profiles in Acute and Chronic Leukemias

Esterase isoenzyme profiles of 255 leukemia-lymphoma cell lines from all hematopoietic cell lineages

Carboxylic esterase isoenzymes isolated from a panel of well-characterized continuous human leukemia-lymphoma cell lines were separated by isoelectric focusing. Typical isoenzyme patterns designated Mono 1/Mono 2 (for monocyte-associated), My 1/My 2 (for myeloid or myeloma), Lym 1/Lym 2 (for lymphoid) and Und (for undifferentiated) could be reproducibly discerned. The Mono patterns contained one unique isoenzyme encoded by the monocyte-specific esterase gene. This comparative analysis of 255 leukemia-lymphoma cell lines covered the major cell lineage that are affected by hematological neoplasias. The results showed that (except for myelomas) lymphoid-derived malignancies, both leukemias and lymphomas, expressed primarily the Und and Lym esterase isoenzyme profiles. In contrast, myeloid leukemia cells and the related erythroid and megakaryocytic cell lines displayed mainly the My patterns. The Mono patterns were detected predominantly in monocyte-derived leukemias. As the B-lymphocytic hierarchy progresses from pre B-cells via B-cells to plasma cells, number and intensity of the isoenzymes increased as well from the Und pattern to the My isoenzyme profile. Hodgkin's disease and anaplastic large cell lymphoma lines displayed heterogenous isoenzyme profiles consistent with their heterogenous cellular origin. The present study using continuous leukemia-lymphoma cell lines as model systems provides a biochemical characterization of different hematopoietic cell lineages and stages of differentiation.

Multiparameter approach in the identification of cross-contaminated leukemia cell lines

A common problem in cell culturing is cross-contamination with other cells or misidentification of cells. An effective cell culture quality and identity control is required in order to avoid inter- and intraspecies contamination of cell lines and their further propagation and dissemination. We present evidence that supposedly unrelated cell lines that we received from the original investigators are in fact related to the chronic myeloid leukemia cell line K-562. The sister cell lines SPI-801 and SPI-802 were originally established from a patient with T-cell acute lymphoblastic leukemia and displayed T-cell associated features. However, data from morphological evaluation, immunophenotyping, bcr-abl gene rearrangement analysis, DNA fingerprinting, Northern blot analysis of globin gene expression and esterase isoenzyme analysis clearly established that the three cell lines are related. Cytogenetic examination while not proving the common identity of the cells provided further evidence for the suspected common origin of all three cell lines. Chromosome banding, DNA fingerprinting and bcr-abl genotyping suggested further evolution of these clones during long-term cultivation. Quality and identity control is an essential feature of cell culture technique. Only regular monitoring for purity and integrity of cell lines will significantly reduce the incidence of cell line contamination and misidentification.

Purification of human monocyte-specific esterase (MSE): molecular and kinetic characteristics

Human monocyte-specific esterase (MSE) derived from leukaemic AMoL-M5 blast cells was purified to homogeneity by the sequential application of anion-exchange, hydrophobic interaction, affinity and gel filtration chromatographic procedures. The resulting enzymatically active MSE primarily existed as an apparent trimer which, under both reducing and non-reducing conditions, dissociated to an inactive 63.4 kD glycoprotein monomer. Electrophoretic studies further confirmed that purified MSE comprised a narrow series of pI (5.5-6.1) forms and one main charge species. Neuraminidase failed to modify observed pI values for individual MSE isoenzymes, and endoglycosidase H treatment revealed that the deglycosylated form of MSE had an apparent molecular weight of 60.1 kD. In support of the known cytochemical characteristics of human MSE, substrate kinetic studies demonstrated that purified enzyme hydrolysed esters of higher acyl chain length (butyrate > propionate > acetate) but did not show peptidase activity. Amino acid sequencing of the MSE N-terminus further revealed that there was almost complete identity with human alveolar macrophage esterase and close similarities with rat and rabbit liver carboxylesterases. These kinetic and molecular studies are particularly important in elucidating the biological and functional role(s) of one of the few haemopoietic cell enzymes that can be considered truly lineage-specific.