Journal of Cell Science, Vol 2, 359-370, Copyright © 1967 by Company of Biologists

Submitted on September 9, 1966
Revised on February 10, 1967

An Electron-Microscope Study of the in vitro Transformation of Human Leucocytes

I. Transformation Of Lymphocytes to Blastoid Cells in the Presence of Phytohaemagglutinin

¹ Rheumatism Research Centre, University of Manchester, and Department of Clinical Haematology, The Royal Infirmary, Manchester
² Rheumatism Research Centre, University of Manchester, and Department of Clinical Haematology, The Royal Infirmary, Manchester; The Charles Salt Research Centre, Robert Jones and Agnes Hunt Orthopaedic Hospital, Oswestry, Salop
³ Rheumatism Research Centre, University of Manchester, and Department of Clinical Haematology, The Royal Infirmary, Manchester; Department of Pathology, University of Manchester

Electron-microscope studies of cultured small lymphocytes from human peripheral blood transforming into larger blastoid cells in the presence of phytohaemagglutinin (PHA) show that the transformed cell possesses the preliminary stages of development of a protein-synthesizing system. The transformed blastoid cell has abundant ribosomes, although, in contrast with in vivo protein-secreting cells, many of these occur as single particles with only a small proportion Linked in polysomal clusters. Endoplasmic reticulum membranes occur to a very limited extent and with a marked paucity of attached ribosomal particles; the few attached particles are usually located in groups. Some endoplasmic reticulum membranes revealed degenerative changes in otherwise normal cells. A moderately well-developed Golgi apparatus was a characteristic feature of the cells. Apart from the relatively low proportion of polysomes, in vitro PHA-transformed blastoid cells are identical in fine structure to in vivo blast cells (otherwise known as immunoblasts, haemocytoblasts, etc.) occurring in the immune response. It is suggested that messenger-RNA production in PHA-stimulated transformed cells may be reduced and that this could explain the limited number of polysomes and the restricted development of the endoplasmic reticulum.