Week 1: Introduction to the Immune System Flashcards
A 4-year-old girl presents with lethargy, dyspnoea, fever, and bruising. On examination, she has hepatosplenomegaly. Blood tests showed low Hb.
A chest x-ray shows a mediastinal mass and pleural effusion. A full blood count and cytogenetic analysis was performed. The girl was diagnosed with acute lymphocytic leukaemia (ALL) and chemotherapy was performed.
Given the information provided what is the likely cause of this girl’s lethargy?
Low haemoglobin levels and anaemia leading to lack of oxygen supply
A 4-year-old girl presents with lethargy, dyspnoea, fever, and bruising. On examination, she has hepatosplenomegaly. Blood tests showed low Hb.
A chest x-ray shows a mediastinal mass and pleural effusion. A full blood count and cytogenetic analysis was performed, which showed high calcium. The girl was diagnosed with acute lymphocytic leukaemia (ALL) and chemotherapy was performed.
Suggest possible reasons for the hypercalcemia seen in this patient?
Hypercalcemia may be caused by bony infiltration or ectopic release of a parathormone-like substance.
Name the hormone that is secreted when blood calcium levels are higher than normal? From where is it secreted?
Calcitonin
Thyroid gland acts to stimulate incorporation of calcium into bone
Suggest why chemotherapy may result in hyperkalaemia?
Potassium is at a higher concentration inside cells and thus extensive cell lysis due to chemotherapy can alter the electrolyte balance in the extracellular fluid leading to hyperkalaemia.
Acute lymphocytic leukaemia patients regularly have a chromosomal abnormality called the Philadelphia chromosome. What type of chromosomal abnormality is this and state the karyotype of the cells?
robertsonian translocation t(9;22)(q34;q11)
State the correct order of abundance of cell types in the peripheral blood?
RBCs, platelets, neutrophils, lymphocytes, monocytes, eosinophils, basophils
List the mature white blood cells would you not see in a peripheral blood smear?
Macrophage
Mast cell
In Acute lymphocytic leukaemia, which type of hematopoietic cell would you find in the peripheral circulation that you would usually find only in bone marrow?
Lymphoblast. The diagnosis of ALL is made when at least 20% lymphoblasts (WHO classification) are present in the bone marrow and/or peripheral blood.
Bone marrow aspirates or biopsies are usually taken from ALL patients to confirm the diagnosis. What histological stain should be used to visualise the different cell types?
Giemsa or Wright stains
What are the two categories of bone marrow tissue?
There are two categories of bone marrow tissue: ‘red marrow’ (medulla ossium rubra), which consists mainly of hematopoietic tissue, and ‘yellow marrow’ (medulla ossium flava), which is mainly made up of fat cells.
A consultant at the hospital is visited by parents of a 7-year-old patient. The young girl has Fanconi’s anaemia a rare, autosomal recessive disease characterised by aplastic anaemia (bone marrow failure), brittle chromosomes, and the variable presence of skeletal, cardiac, and renal anomalies. The parents understand that definitive treatment of the disorder relies on reconstituting the patient’s bone marrow by transplantation or cord blood donation. They would like to talk about having another baby and using the cord blood to help their daughter.
Which type of bone marrow would be the major component of their daughter’s bone marrow?
There are two categories of bone marrow tissue: ‘red marrow’ (medulla ossium rubra), which consists mainly of hematopoietic tissue, and ‘yellow marrow’ (medulla ossium flava), which is mainly made up of fat cells.
From birth to early adolescence, the majority of our bone marrow is red marrow.
Describe the blood vessel of umbilical cord?
Two umbilical arteries - Deoxygenated blood from fetus to placenta
One umbilical vein- Oxygenated blood from placenta to fetus
A consultant at the hospital is visited by parents of a 7-year-old patient. The young girl has Fanconi’s anaemia a rare, autosomal recessive disease characterised by aplastic anaemia (bone marrow failure), brittle chromosomes, and the variable presence of skeletal, cardiac, and renal anomalies. The parents understand that definitive treatment of the disorder relies on reconstituting the patient’s bone marrow by transplantation or cord blood donation. They would like to talk about having another
baby and using the cord blood to help their daughter.
What cells should be harvested from the cord blood to best treat patients with blood diseases?
Stem cells - Although erythrocytes and leukocytes might be helpful in the short term, it makes more sense to harvest and implant stem cells that can create new erythrocytes and leukocytes.
Describe the process of Haematopoiesis?
Haematopoietic stem cells (HSCs) reside in the medulla of the bone (bone marrow) and have the unique ability to give rise to all of the different mature blood cell types and tissues.
Daughter cells of HSCs (myeloid and lymphoid progenitor cells) can follow any of the other differentiation pathways that lead to the production of one or more specific types of blood cell, but cannot renew themselves.
All blood cells are divided into three lineages.
Erythroid cells are the oxygen carrying red blood cells. Both reticulocytes and erythrocytes are functional and are released into the blood.
Lymphocytes are derived from common lymphoid progenitors. The lymphoid lineage is primarily composed of T-cells and B-cells (types of white blood cells).
Myelocytes, which include granulocytes, megakaryocytes and macrophages and are derived from common myeloid progenitors, are involved in innate immunity, adaptive immunity, and blood clotting.
Aplastic anaemia causes pancytopenia, a deficiency of all three blood cell types. Name the three types?
Red blood cells (anaemia), white blood cells (leukopenia), and platelets (thrombocytopenia).
What is the probability of a naturally conceived child would also have Fanconi’s anaemia, an autosomal recessive disease?
25%
two broad categories of immunity
Innate immunity – the mechanisms have evolved to be ready to react before an infection occurs. The innate immune system provides the first and some of the second line of defences.
Adaptive immunity – The system is stimulated by microbes and the mechanisms ‘adapt’ to this stimulus to build an immune response.
Cells of innate immune system
epithelial cells mast cells phagocytes dendritic cells NK cells complement system
Cels of adaptive immunity
B lymphocytes > plasma cells and antibodies
T lymphocytes > effector T cells
Describe the first and second line of defence of the innate immune system.
First - These are a combination of physical and chemical barriers that prevent all types of foreign agents from penetrating the outer layer of the body. No specific foreign agent is targeted at this level.
Second - Leukocytes (white blood cells)
Leukocytes are derived from…
Leukocytes derived from pluripotent stem cells in the bone marrow protect
five types of leukocytes
neutrophils, eosinophils, basophils, lymphocytes, and monocytes
Two major classifications of leukocytes
Granulocytes (with granules). Granulocytes are mainly involved in non-specific responses. The granules contain a rich blend of killer molecules and metabolic pathways that can generate low pH and oxidizing agents. Release of the granules to the extracellular environment will be highly lethal to pathogens but also to surrounding tissue.
Agranulocytes (without granules). Agranulocytes can play a role in both specific and non-specific immune responses.
Classify the 5 leucocytes into granulocytes vs. agranulocutes
Granulocytes: neutrophils, eosinophils, basinophils
Agranulocutes - lymphocytes, monocytes