Thromboplastin as a marker for monocyte differentiation

Abstract

The thromboplastin synthesis of the human monocytoid cell line U-937 and its two subclones designated U-937-3 and U-937-4 has been studied. U-937-4 seems by several functional criteria to represent a more advanced stage of monocyte differentiation than the original U-937. U-937-3 appears to be arrested at an even more immature stage than the original population. The basal thromboplastin activity was higher in U-937-4 than in U-937-3 or U-937 cells (7.0 +/- 1.9 (SEM), 1.0 +/- 0.2 and 1.6 +/- 0.6 units/mg protein, respectively) although not as high as in human normal monocytes (14.1 +/- 2.4). The thromboplastic expression of the two clones was maximal when cells were in logarithmic growth. Both clones responded with a weak to moderate thromboplastin synthesis upon addition of stimulants like phytohaemagglutinin (PHA), immune complexes or endotoxin. Thromboplastin production was also potentiated in the presence of lymphocytes. The supporting effect of lymphocytes was strong in the case of U-937-3 as well as in U-937 cells, but less pronounced in U-937-4 cells as it also is in human monocytes. The thromboplastin response after PHA stimulation was more rapid in U-937-4 cells (maximal after 4-8 h) than in U-937 or U-937-3 cells (12-16 h). Human monocytes also responds quickly to PHA (maximally 4 h). Total phospholipid content and the relative distribution of individual phospholipids were essentially similar in U-937-3, U-937-4 and U-937. With regard to thromboplastin production, U-937-4 cells seem to be more monocyte-like than the more immature cells U-937-3 and U-937. It is concluded that thromboplastin seems to be a useful marker for monocyte differentiation.

Expression of leukocyte integrins and tissue factor in mononuclear phagocytes

“…The skewed distribution of CD11b/CD18 and CD11c/ CD18 amongst subfractions of AM may also reflect that monocytes turn on the expression of these adhesion molecules in the process of their migration from the vasculature to become AM and that the same molecules are downregulated during the further differentiation process of AM. The importance of CD11b-induced coagulation thus probably decreases as AM mature, while the role of the TF-driven system is maintained or even enhanced, in line with earlier observations that TF represents a differentiation marker for mononuclear phagocytes [27,28] and, thus, TF is maximally expressed in the most mature AM.…”

A Quantitative Study of Monocyte Procoagulant Activity in Acute Monoblastic and Chronic Myelomonocytic Leukaemias

“…It is of interest that most cases of CMML generated normal amounts of PCA, confirming that a more ma ture cell is implicated in this disease [8,9].…”

“…Conversely, the impaired monocyte PCA in patients with chronic lymphocytic leukaemia [14] and chronic myeloid leukeamia [15] is felt to contribute to the low incidence of DIC in these conditions. It is therefore of interest that DIC is a recognised complication of AML, although immature monocytes demonstrate a markedly impaired generation of PCA [8,9], The ex act incidence of DIC in AML is unknown, but ap pears to be less frequent than in APML. In a recent retrospective analysis of 61 patients with AML [2], 16 patients had laboratory evidence of DIC, and this correlated significantly with the presence of hyperleucocytosis.…”

“…pro coagulants [4], The major monocyte procoagulant ac tivity (PCA) is thromboplastin, which can be gene rated in vitro in response to a variety of stimuli [5][6][7], and the spontaneous release of procoagulants such as thromboplastin from monoblasts has been suggested as a cause of the DIC in AML. However, immature monocytes have recently been reported to have a mar kedly impaired generation of PCA [8,9], suggesting that this may not be the mechanism underlying the DIC complicating AML. The aim of this study was to measure the PCA of monocytes from patients with AML and chronic myelomonocytic leukaemia (CMML) to assess the potential contribution of mon ocyte PCA to coagulation abnormalities seen with AML but not CMML [10],…”

Monocyte Procoagulant Activity as a Peripheral Marker of Clotting Activation in Cancer Patients

“…It is difficult to resolve the discrepan cies among these studies particularly since other phenotypic characteristics of the cells were not provided. It is well known that TF generation is a correlate of monocyte 'activa tion' [66] and several studies have demon strated the relationship of TF generation and cell differentiation in normal [43,74] and leukemic cells [75][76][77]. Therefore, one might predict quite variable responses to stimula tion in population of cells from patients with leukemia since each cell culture could con tain a mixture of both normal and defective monocytes.…”