Erythroid differentiation of Friend cells

The process of erythropoiesis has been reviewed by Harrison (1976, 1977) and Orkin (1978) and more recently Metcalf (1989) has reviewed haemopoiesis from the molecular point of view. Erythroid cells together with the other blood cells are derived from a common haematopoietic stem cell. After commitment to the erythroid lineage the stem cells proliferate for a few generations when they become sensitive to the hormone erythropoietin which increases the proliferation of committed erythroid stem cells and proerythroblasts which then differentiate into mature erythroid cells containing haemoglobin. 

Studies with normal erythropoietic systems are hampered by the difficulties of obtaining sufficient erythroid cells of specific developmental stages. However, cell strains are available of both human and murine origin which allow the study of the final stages of erythroid development in vitro. 

Friend cells are murine, virus-transformed, erythroleukaemic (MEL) cells which grow in culture in suspension and exhibit a limited degree of differentiation along the erythroid line (Friend et al., 1966 Patuleia and Friend, 1967). The target cell for the Friend 

Marks and Rifkind (1978) have reviewed the characteristics of the induced differentiation and listed the large variety of inducers (e.g. butyric acid, hemin, ouabain) which may be used in place of dimethylsulphoxide. However, not all these inducers produce the same effects in all the clones tested and some DMSO resistant variants exhibit different phenotypes (Harrison et al., 1978). The most commonly used inducers are DMSO and HMBA (hexamethylene bi-sacetamide). 

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