Haematology

Christian S. R. Hatton, Deborah Hay, David M. Keeling

• Publisher: Wiley-Blackwell
• Year: 2017
• Print ISBN: 9781119264255
• eBook ISBN: 9781119264279
• Edition: 10
• Topic: Medicine
• Subtopic: Medical Theory, Practice & Reference

As the science and practice of haematology continues to advance at a considerable rate, Haematology Lecture Notes remains a comprehensive guide to this diverse subject, and provides support in understanding the pathogenesis and management of haematological disorders.

Successfully integrating the physiological, pathological, and clinical aspects of haematology, this new edition includes new material on molecular and cellular diagnostics, expanded coverage on haemostasis, malignant haematology and transplant, and features self-assessment questions at the end of each chapter.

Thoroughly revised and updated, Haematology Lecture Notes provides the core subject knowledge required by students and junior doctors to excel in this specialty. 

Chapter 1
An introduction to haematopoiesis

---

Learning objectives

• 
  To understand the process of formation of blood cells
• 
  To understand the concept of a stem cell
• 
  To appreciate the processes of lineage specification of blood cells
• 
  To recognize the different types of mature blood cell
• 
  To understand the normal role of each mature cell type in the blood

---

Where is blood formed?

As the developing embryo grows, it starts to require a means of delivering oxygen to tissues for respiration. The circulation and blood develop at the same time, from around 3 weeks' gestation, and there are close links between the cellular origins of the first blood cells and the vasculature. Haematopoietic stem cells originate in the para-aortic mesoderm of the embryo. Primitive red blood cells, platelet precursors and macrophages are initially formed in the vasculature of the extra-embryonic yolk sac, before the principal site of haematopoiesis shifts to the fetal liver at around 5–8 weeks' gestation. The liver remains the main source of blood in the fetus until shortly before birth, although the bone marrow starts to develop haematopoietic activity from as early as 10 weeks' gestation.

After birth, the marrow is the sole site of haematopoiesis in healthy individuals. During the first few years of life, nearly all the marrow cavities contain red haematopoietic marrow, but this recedes such that by adulthood haematopoiesis is limited to marrow in the vertebrae, pelvis, sternum and the proximal ends of the femora and humeri, with minor contributions from the skull bones, ribs and scapulae.

Although the sites of haematopoiesis in the adult are therefore relatively limited, other sites retain their capacity to produce blood cells if needed. In conditions in which there is an increased haematopoietic drive (such as chronic haemolytic anaemias and chronic myeloproliferative disorders), haematopoietic tissue will expand and may extend into marrow cavities that do not normally support haematopoiesis in the adult. Foci of haematopoietic tissue may also appear in the adult liver and spleen and other tissues (known as extramedullary haematopoiesis).

Haematopoietic stem cells

The process of haematopoiesis involves both the specification of individual blood cell lineages and cellular proliferation to maintain adequate circulating numbers of cells throughout life. This is accomplished using the unique properties of haematopoietic stem cells.

Long-term haematopoietic stem cells (HSCs) in the bone marrow are capable of both self-renewal and differentiation into the progenitors of individual blood cell lineages. The progenitor cells of individual lineages then undergo many rounds of division and further differentiation in order to yield populations of mature blood cells. This process can be represented as a hierarchy of cells, with HSCs giving rise to populations of precursor cells, which in turn give rise to cells increasingly committed to producing a single type of mature blood cell (Figure 1.1). Thus, the immediate progeny of HSCs are the multipotent progenitor cells, which have limited self-renewal capacity but retain the ability to differentiate into all blood cell lineages. Although there is still debate about exactly how lineage-restricted subsequent precursors are, the concept of sequential and irreversible differentiation is widely accepted. In Figure 1.1, the HSC is seen giving rise to two major lineages: the lymphoid lineage, in which a common lymphoid progenitor gives rise to B cells, T cells and natural killer (NK) cells; and a myeloid lineage, with a common myeloid progenitor giving rise to red cells, granulocytes and platelets. The division of haematopoiesis into myeloid and lymphoid compartments is fundamental to an understanding of haematological disease.

Figure 1.1 A schematic representation of the process of haematopoiesis. Multipotent stem cells give rise to lymphoid (pink) and myeloid (blue) lineages. The myeloid lineage further divides into granulocytic, erythroid and megakaryocytic (platelet) lineages. As cells progress through this process of differentiation, they accrue more functional specialization and lose their multipotency. GMP, granulocyte macrophage progenitor; HSC, haematopoietic stem cell; MEP, megakaryocyte/erythroid progenitor; NK, natural killer.

The process of haematopoiesis outlined above has several advantages. First...

Table of contents

• Cover
• Title Page
• Copyright
• Table of Contents
• Preface
• About the companion website
• Chapter 1: An introduction to haematopoiesis
• Chapter 2: Anaemia: General principles
• Chapter 3: Haemolytic anaemias
• Chapter 4: Disorders of globin synthesis
• Chapter 5: Conditions associated with white cell abnormalities
• Chapter 6: Structure and function of lymphoid tissue
• Chapter 7: Lymphomas: General principles
• Chapter 8: Classification of lymphoma
• Chapter 9: Neoplastic disorders of lymphoid cells
• Chapter 10: Plasma cell myeloma and other paraproteinaemias
• Chapter 11: Neoplastic disorders of myeloid cells
• Chapter 12: Bone marrow transplantation
• Chapter 13: Aplastic anaemia and pure red cell aplasia
• Chapter 14: Haemostasis, abnormal bleeding and anticoagulant therapy
• Chapter 15: Blood groups and blood transfusion
• Chapter 16: Cellular and molecular investigations in haematology
• Index
• End User License Agreement