CSB329H1 Lecture 9: Lecture 9 Part 1
9 May 2018
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Lecture 9(a): Hematopoietic Stem Cells
Hematopoietic Stem Cells (HSCs):
• Multipotent stem cell that is capable of differentiating into a:
o (1) Lymphoid Progenitor Cell (2) Myeloid Progenitor Cell
Lymphoid Progenitor Cell:
• Further differentiate into: (1) Natural Killer Cell (2) T or B lymphocytes
Myeloid Progenitor Cell:
• Further differentiate into: (1) Neutrophil (2) Basophil (3) Eosinophil (4) Platelets
(5) Monocyte/Macrophage (6) Red Blood Cells
Hematopoiesis:
• Process through which all cellular components of the blood are formed: red/white blood cells
o Hematopoietic Stem Cells (HSCs) differentiate into either:
§ (1) Lymphoid Progenitor Cell (2) Myeloid Progenitor Cell
• ~10,000 HSCs in bone marrow, and ~1000 contribute to hematopoiesis; the remaining ~9000
are quiescent – at rest, and are found in G0 cell cycle
Lymphoid Progenitor Cell:
• Further differentiate into: (1) Natural Killer Cell (2) T or B lymphocytes
Myeloid Progenitor Cell:
• Further differentiate into: (1) Neutrophil (2) Basophil (3) Eosinophil (4) Platelets
(5) Monocyte/Macrophage (6) Red Blood Cells
Bone Marrow Transplant:
• Two patients have leukemia, and both had an identical twin
o Patients did not respond to chemotherapy and marrow was obtained from their
identical twin and transplanted to the patients – the transplanted marrow appeared to
graft and no ‘graft vs host’ disease (GVHD) was observed
ð Allogenic transplants are possible IF the patient and donor are human leukocyte antigen
(HLA) matched
Human Leukocyte Antigen (HLA) System/Complex:
• Group of genes that encode the major histocompatibility complex (MHC)
o MHC Class I (A, B, C) – present peptides from inside the cell
o MHC Class II (DR, DQ, DP) – present antigens from outside the cell to T-cells
§ Allows the immune system to recognize and respond differently to self vs
foreign cellular components
ð Major cause of bone marrow transplant rejection, which is known as ‘Graft vs Host Disease’
o Occurs when transplanted immune cells recognize the recipient’s cells as foreign
Highly polymorphic
in human population
Document Summary
Lecture 9(a): hematopoietic stem cells: multipotent stem cell that is capable of differentiating into a: (1) lymphoid progenitor cell (2) myeloid progenitor cell. Lymphoid progenitor cell: further differentiate into: (1) natural killer cell (2) t or b lymphocytes. Myeloid progenitor cell: further differentiate into: (1) neutrophil (2) basophil (3) eosinophil (4) platelets (5) monocyte/macrophage (6) red blood cells. Allogenic transplants are possible if the patient and donor are human leukocyte antigen (hla) matched. Allows the immune system to recognize and respond differently to self vs foreign cellular components. Major cause of bone marrow transplant rejection, which is known as graft vs host disease": occurs when transplanted immune cells recognize the recipient"s cells as foreign. Allogenic therapy with hla matching: hla matching is often found in a sibling however, can be found in an unrelated individual from a bone marrow registry, hla homozygous can be donors for more individuals.
