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PHGY 209 > Immunology IV > Flashcards

Immunology IV Flashcards

1
Q

What is the cellular component of the adaptive immune system?

A

Cytotoxic T cells directly attack antigen-bearing cells.

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2
Q

Lymphocytes develop receptors for every pathogen that we might experience by the process of […]

A

Somatic hypermutation

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3
Q

Somatic hypermutation occurs in […]

A

B cells and T cells

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4
Q

What are the two enzymes involved in somatic hypermutation?

A
  1. The Recombination activating genes (RAGs)
  2. Terminal Deoxynucleotidyl Transferase (TdT)
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5
Q

Describe the function of RAGs in somatic hypermutation.

A

The Recombination activating genes (RAGs) will splice out some of the V, D, and J genes on the DNA, leading to a reduced pool of possible genetic combinations for receptors.

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6
Q

Describe the function of TdT in somatic hypermutation.

A

The Terminal Deoxynucleotidyl Transferase (TdT) will add single nucleotides to the ends of these gene blocks, which will cause frame shifts and further change the combinations of receptors. It will ultimately splice out one V, one D, and one J for the variable region.

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7
Q

What is the end product of somatic hypermutation?

A

The end result will be mRNA with one variable region made up of a V, D, and J gene, and one constant region, made up of a C gene.

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8
Q

The category of antibody (IgE, IgG, etc.) is determined by its […] region.

A

Constant

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9
Q

When you get an infection, the first antibodies to be produced in the primary response are […]. because […]. They are followed by […] in [smaller/equal/greater] quantites.

A

IgMs, because they are good for activating complement. igGs, equal.

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10
Q

The secondary response to an infection involves the production of which antibody type(s) and in what quantities?

A

It results in the rapid production of a lot of IgGs and a small quantity of IgMs.

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11
Q

The first time you have an infection, the first antibody to respond is […]. Why?

A

IgMs, because they are good at activating complement due to their large size.

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12
Q

The second time you get an infection, the first antibody to respond is […]. Why?

A

Although IgGs and IgMs both respond, IgGs dominate because they are effective in moving throughout the body.

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13
Q

When you get an infection in mucosal tissue, the major antibody to be produced will be […]

A

IgAs

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14
Q

How does the body know not to attack its own cells?

A

It recognizes the major histocompatibility complex (MHC) of the body, which is unique (except in identical twins). During development, any lymphocytes that might target our own body are removed.

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15
Q

The process of getting rid of lymphocytes that might attack our own body cells is called […], which has the end goal of […]. When does it occur?

A

Clonal deletion/clonal inactivation, immune tolerance. It occurs during fetal and early postnatal life.

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16
Q

Describe the steps by which the development of T cell tolerance occurs

A
  1. T cells that don’t recognize MHC Class II are negatively selected, as this makes them useless.
  2. T cells that recognize MHC Class I-self peptide complexes are negatively selected to prevent against self-attack.
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17
Q

[…]% of T cells never leave the thymus. Why?

A

95%. This is because after negatively selecting for T cells that either can’t recognize MHC II or can recognize MHC I-self, there are not many left that are of use to the body.

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18
Q

Why do we get an amplified immune response upon second exposure to disease?

A

Because of the memory cells produced by B and T cells. This allows for faster and greater production of the correct antibodies to fight off the infection.

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19
Q

What is the role of T cells in the adaptive immune system? How do they get activated?

A

They are used in cell-mediated immunity to eliminate specific antigens. They only get activated once they see the foreign antigens that they target.

20
Q

What is the difference between an exogenous antigen and an endogenous antigen?

A

An exogenous antigen leads to the antigen-presenting cell that we’ve seen thus far. It is when something from the outside is producing an immune response, such as a toxin from bacteria. An endogenous antigen is when the body cells get infected and themselves produce the immunogen.

21
Q

How does the response of the immune system differ for endogenous antigens as opposed to exogenous antigens?

A

In the case of exogenous antigens, MHC II molecules are synthesized by APCs and bound to the fragments of antigen, and presented by antigen-presenting cells. On the other hand, for endogenous antigens, MHC I molecules are synthesized by the infected cell and bound to fragments of the antigens, which are then presented to T cells in a similar way.

22
Q

Explain the process by which cytotoxic T cells get activated.

A

In a secondary lymphatic organ, a dendritic cell will still bring in a pathogen and present it with the MHC-II molecule. This leads to the activation of the helper T cell, which then activates the cytotoxic T cell by releasing cytokines (no direct contact).

23
Q

Explain how cytotoxic T cells deal with infected body cells once they’ve been activated.

A

The cytotoxic T cell will find a match for its receptor by travelling out of the secondary lymphatic organ. Its receptors have to match infected cells via a recognition event. The infected cell must be presenting the antigen along with the MHC I protein for the recognition event to be successful. The cytotoxic T cell will then release perforins and granzymes to kill the cell.

24
Q

Explain the process by which infected body cells present antigens with MHC-I.

A

When the cell has been taken over and is producing viral proteins, these proteins will be digested into fragments. At the same time, MHC-I molecules will be produced, as they normally would be, and they get packaged together and displayed on the cell via exocytosis.

25
Q

Describe the recognition event between the cytotoxic T cell and the infected body cell.

A

The cytotoxic T cell receptor must meet with the Class 1 MHC protein with the endogenous antigen. Protein CD8 will also participate in the recognition event. The recognition event, along with cytokines from the helper T cell, will also cause the proliferation of cytotoxic T cells.

26
Q

When does the proliferation of cytotoxic T cells take place relative to the recognition event with an infected cell?

A

It takes place after the recognition, as that plus cytokines from the helper T cell are what prompt its replication.

27
Q

How does the cytotoxic T cell kill the infected body cell?

A

By releasing perforins and granzymes.

28
Q

What is the fate of cytotoxic T cells after they’ve interacted with and killed a body cell?

A

They will survive and go on to infect the next infected cell.

29
Q

What is the involvement of CD4 and CD8 proteins on T cells in the immune system?

A

They help with the recognition events of their respective cells. For helper T cells, CD4 assists in the interaction with the APC MHC-II antigen complex. For cytotoxic T cells, CD8 assists in the interaction with the infected body cell and the MHC-I antigen complex.

30
Q

Name 5 factors that might alter resistance to infection.

A

Protein-calorie malnutrition, preexisting disease, stress and state of mind, modest exercise and physical conditioning, and sleep deprivation

31
Q

What is the greatest contributor to decreased resistance to infection worldwide?

A

Protein-calorie malnutrition

32
Q

Explain how protein-calorie malnutrition affects resistance to infection.

A

Nutrient deficiencies will affect the synthesis of white blood cells, and there are many energy-dependent processes on which immune responses rely.

33
Q

Name two immunodeficiency diseases (name and acronym)

A

Severe combined immunodeficiency disease (SCID)
Acquired immunodeficiency syndrome (AIDS)

34
Q

How does having AIDS affect the immune system?

A

It infects and kills helper T cells, resulting in impaired immune responses to infectious organisms.

35
Q

How does having SCID affect the immune system?

A

It is the result of an absence of both B and T cells, and sometimes NK cells due to the absence of bone marrow. This results in a group of related diseases arising from the immunodeficiency.

36
Q

Give 5 examples of harmful immune responses.

A

Graft rejection, transfusion reactions, allergy, autoimmune disease, and excessive inflammatory responses.

37
Q

Explain why graft rejection/the rejection of organ transplants might occur.

A

This can occur because class I MHC proteins on the graft cells and class II proteins on the macrophages differ from the recipient. So, the MHC proteins are recognized as foreign by the recipient’s T cells and cytotoxic T cells will be activated to destroy them.

38
Q

Give an example of a drug that can prevent graft rejection and explain how it works.

A

Cyclosporine can help, as it blocks the production of IL-2 and other cytokines by helper T cells, eliminating the signal from the helper T cells for the proliferation of cytotoxic T cells.

39
Q

What is a potential side effect of cyclosporine? Explain why.

A

It may leave an individual more vulnerable to other illnesses, as their adaptive immune system becomes less active with the suppression of IL-2 and other cytokines from T helper cells.

40
Q

Explain why transfusion reactions might occur.

A

Although erythrocytes lack MHC proteins, they have plasma membrane proteins that function as antigens. A person of a given blood type will have antibodies against the antigens they don’t naturally have, which can lead to an immune response in the case of a blood type mismatch.

41
Q

For blood groups A, B, AB, and O, what are the antigens on the individual’s RBCs and the antibodies present in their blood?

A

A: Has A antigen, anti-B antibodies
B: Has B antigen, anti-A antibodies
AB: Has A and B antigens, neither anti-A nor anti-B antibodies.
O: Has neither A nor B antigens, has both anti-A and anti-B antibodies.

42
Q

What is an allergic reaction?

A

A reaction that occurs when a person is overly reactive to a substance that most others tolerate well.

43
Q

What are the two types of allergic reaction? Explain the difference between them.

A

Immediate hypersensitivity: occurs immediately after exposure
Delayed hypersensitivity: occurs 12-72 hours after allergen exposure

44
Q

The major leukocyte type involved in allergic reactions is […], which secrete […]

A

Mast cells, an excess of histamine

45
Q

What is anaphylaxis? How does it occur?

A

While allergic symptoms are usually localized to the site of antigen entry, if large amounts of histamine released by mast cells enter the circulation, this can result in severe hypotension and bronchiolar constriction.

46
Q

What is autoimmune disease?

A

It is a disease that leads to an inappropriate immune attack triggered by the body’s own proteins acting as antigens.

47
Q

Give 3 examples of autoimmune diseases.

A

Type 1 diabetes, rheumatoid arthritis, multiple sclerosis, myasthenia gravis

PHGY 209 (33 decks)

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