Il sistema immunitario di Stefania Artigiani (stefania.artigiani@libero.it), Annalisa Balanzoni (a.balanzoni@virgilio.it), Alessandra Bosia (ventiene@libero.it)

EVALUATION TEST

1. Connect each organ to the corresponding function:

1) Lymph node A) development of self-tolerance
2) Spleen B) avoid the entry of pathogens through mucosae
3) Bone marrow C) drainage of surplus fluid from intercellular spaces
4) Thymus D) remove particulate matter (e.g. red blood cells and platelets) from the circulation
5) lymphatic capillaries E) immunologic filter for lymph
6) MALT F) haematopoiesis

2. Connect each function/characteristic to the corresponding white blood cells (there may be more than one corresponding cell for each function/characteristic):

A) phagocytosis 1) T lymphocyte
B) secretion of citokines 2) Macrophage
C) antigen presenting cell 3) Basophil
D) are involved in inflammation 4) B lymphocyte
E) contains cytoplasmic granules 5) Neutrophil
F) generate specific immune responses 6) Dendritic cell
G) induce lysis of the target cell 7) Eosinophil
H) secrete antibodies 8) Natural killer cell

3. Define and describe the following molecules or processes:

a) Haematopoiesis
b) Complement
c) Phagocytosis
d) Cytokines

4. Define “innate immunity” and list the mechanisms, through which it acts.

5. Connect each event to the corresponding specific immune phase (there may be more than one corresponding phase for each event):

1) Recognition phase
2) Activation phase
3) Effector phase
4) Suppressor phase

A) Cytotoxic T cells lyse infected cells
B) T and B lymphocytes proliferate and differentiate in effector and memory cells
C) T-helper cells release cytokines to attract other immune cells in inflammation site
D) Lymphocytes and macrophages secrete a cytokine which prevents the activation of macrophages and the maturation of cytotoxic T cells
E) Cytotoxic T cell interacts with an infected cell, which expose an antigen in association with a class I MHC molecule
F) Macrophages endocyte non self molecules, reducing them to fragments and exposing these in association with class II MHC molecules
G) Plasma cells produce antibodies
H) T-helper cells interact with B lymphocytes

6. a) Which cells express MHC class I molecules and with which cells do they interact through MHC class I molecules?
b) Which cells express MHC class II molecules and with which cells do these cells through MHC class II molecules?


7. Connect each sentence to the corresponding subject (there may be more than one corresponding subject for each sentence):
1) extracellular bacteria A) represent the category responsible for the greatest number of diseases in the world
2) intracellular bacteria B) are capable of surviving and replicating inside the cells of our organism
3) viruses C) are recognized and eliminated by cytotoxic T cells
4) parasite D) can cause septic shock
5) tumors E) are able to replicate in the blood circulation

8. Explain the following characteristics of the adaptive (acquired) immunity:

a) specificity
b) diversity
c) memory
d) limitation
e) self/non-self recognition

9. Connect each sentence to the corresponding subject (there may be more than one):

1) humoral immune responses A) produce highly specific antibodies
2) B lymphocytes B) circulate in the blood and lymph streams
3) antibodies C) survive for many years in the body
4) plasma cells D) are mediated by B-cells and antibodies
5) memory cells E) recognize and bind specific antigens
F) undergoes clonal selection
G) are grouped in five classes
H) originate and grow to maturity in the bone marrow

10. Describe the following disorders of the immune system:

1) allergy
2) autoimmune disease
3) primary immunodeficiency
4) acquired immunodeficiency

Answers

Answer to question 1

1 E
2 D
3 F
4 A
5 C
6 B

Answer to question 2

A 2, 5, 6, 7
B 1, 2
C 2, 6
D 2, 3, 5
E 2, 3, 5, 7, 8
F 1, 4
G 1, 8
H 4

Answer to question 3

a) formation of blood cells in the bone marrow
b) system of serum proteins involved in the innate immune response; it is activated by antibody-antigen complexes or micro-organisms and undergoes a cascade of proteolytic reactions, the end result of which is the assembly of membrane attack complexes
c) ingestion and destruction of foreign material by cells of the immune system; involves different phases: chemotaxis, adhesion, engulfment, digestion
d) signalling proteins secreted by macrophages and lymphocytes

Answer to question 4

Innate immunity consists of a series of rapid responses coordinated through "innate" receptors that recognize a wide spectrum of conserved pathogenic components; these defence mechanisms are constitutive and do not require prior activation by the specific antigen.
It acts through: phagocytic cells, anti-microbial proteins, fever.

Answer to question 5

1 E, H
2 B, C, F, H
3 A, F, C, G
4 D

Answer to question 6

a) 90% of the body’s nucleate cells express MHC class I molecules; these cells interact with cytotoxic T cells through MHC class I molecules.
b) Only APCs (Antigen Presenting Cells) express MHC class II molecules; these cells (dendritic cells, macrophages, B lymphocytes and epithelial cells) interact with T helper cells through MHC class II molecules.

Answer to question 7

1 D, E
2 B, C
3 B, C
4 A, B, C, E
5 C

Answer to question 8

a) the immune responses are highly specific for different antigens, as single lymphocytes are able to discriminate between very similar molecules
b) the whole number of antigens that can be recognized by lymphocytes is extremely large
c) the immune system memorizes the first contact with a foreign antigen, so that the following reaction to the same antigen is faster and more intense
d) the immune response progressively switches-off upon antigen removal, and the system returns to a resting condition
e) the immune system can distinguish among self and non-self components on the basis of the MHC: any cell not displaying this marker is considered non-self and attacked

Answer to question 9

1 D
2 E, F, H
3 B, E, G
4 A
5 C

Answer to question 10

1) results from immune system over-reaction to an allergen (dust, pollen, animal hair, certain foods and drugs) that usually does not cause an immune response; it is mediated by IgE antibodies and involves the release of histamine
2) occurs when the immune system is unable to distinguish between self and non-self, and mistakenly attacks the body's healthy organs and tissues as though they were foreign invaders. Autoimmune diseases are i.e. myasthenia gravis, juvenile diabetes, multiple sclerosis, systemic lupus erythematosus, and rheumatoid arthritis
3) congenital form of immune system failure resulting from the lack of cell-mediated or antibody-mediated immune responses
4) secondary form of immunodeficiency due to another disease (i.e. viral infection) or a drug treatment that reduces the immune system's ability to fight infections

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