ADAPTIVE IMMUNITY (GPT EDITION)

Question 1

What are the two main types of adaptive immunity?

Answer 1

Humoral immunity and cell-mediated immunity.

Question 2

Where do B cells mature?

Answer 2

In the bone marrow

Question 3

What is the primary function of B cells?

Answer 3

To produce antibodies for humoral immunity.

Question 4

Where do T cells mature?

Answer 4

In the thymus.

Question 5

What are the two main types of T cells?

Answer 5

Helper T cells (CD4+) and Cytotoxic T cells (CD8+)

Question 6

What is the role of cytotoxic T cells?

Answer 6

To kill virus-infected cells and tumor cells.

Question 7

What molecule is required for T cell antigen recognition?

Answer 7

The T cell receptor (TCR).

Question 8

Which MHC class presents antigens to CD8+ T cells?

Answer 8

MHC class I.

Question 9

Which MHC class presents antigens to CD4+ T cells?

Answer 9

MHC class II.

Question 10

What are antigen-presenting cells (APCs)?

Answer 10

Dendritic cells, macrophages, and B cells.

Question 11

What is clonal selection?

Answer 11

The process where only lymphocytes that recognize an antigen proliferate and differentiate.

Question 12

What are memory cells?

Answer 12

Long-lived immune cells that provide rapid response to previously encountered antigens.

Question 13

Which antibody is the first produced in an infection?

Answer 13

IgM.

Question 14

Which antibody is the most abundant in blood?

Answer 14

IgG.

Question 15

Which antibody is found in secretions like saliva and tears?

Answer 15

IgA.

Question 16

Which antibody is involved in allergic reactions?

Answer 16

IgE.

Question 17

What is opsonization?

Answer 17

The process where antibodies coat a pathogen to enhance phagocytosis.

Question 17

What is the main function of regulatory T cells (Tregs)?

Answer 17

To suppress immune responses and prevent autoimmunity.

Question 18

What is the function of perforin in cytotoxic T cells?

Answer 18

To create pores in infected cells, leading to apoptosis.

Question 19

What cytokine stimulates T cell proliferation?

Answer 19

IL-2.

Question 20

What is the difference between primary and secondary immune response?

Answer 20

Primary response is slow with mainly IgM production; secondary response is faster with IgG dominance.

Question 21

What is affinity maturation?

Answer 21

The process by which B cells produce antibodies with increased antigen-binding strength.

Question 22

What is the role of CD40 ligand (CD40L) in B cell activation?

Answer 22

It binds CD40 on B cells, helping their activation and antibody production.

Question 23

What is somatic hypermutation?

Answer 23

A process in B cells that introduces mutations to improve antibody affinity

Question 24

Which immunodeficiency is characterized by the absence of both B and T cells?

Answer 24

Severe Combined Immunodeficiency (SCID).

Question 25

Which cells are primarily affected in HIV infection?

Answer 25

CD4+ T cells.

Question 26

What is the Fas/FasL pathway?

Answer 26

A mechanism for apoptosis in immune regulation and cytotoxic T cell function.

Question 27

What are superantigens?

Answer 27

Toxins that cause excessive activation of T cells, leading to cytokine storm.

Question 28

What is the purpose of adjuvants in vaccines?

Answer 28

To enhance the immune response.

Question 29

How do tumor cells evade immune detection?

Answer 29

By downregulating MHC molecules or producing immunosuppressive cytokines.

Question 30

What is the difference between central and peripheral tolerance?

Answer 30

Central tolerance occurs in the thymus/bone marrow; peripheral tolerance occurs in mature lymphoid tissues.

Question 31

What are the main cytokines secreted by Th1 and Th2 cells?

Answer 31

Th1: IFN-γ (activates macrophages), Th2: IL-4, IL-5, IL-13 (stimulate B cells and eosinophils).

Question 32

What is cross-presentation in antigen processing?

Answer 32

The ability of dendritic cells to present extracellular antigens via MHC I to CD8+ T cells.

Question 33

Which complement protein initiates the classical pathway?

Answer 33

C1q.

Question 34

What is the difference between active and passive immunity?

Answer 34

Active immunity results from exposure to an antigen (infection/vaccine); passive immunity comes from antibody transfer (maternal antibodies, immunoglobulin therapy).

Question 35

Which hypersensitivity type involves immune complexes?

Answer 35

Type III hypersensitivity.

Question 36

What is molecular mimicry in autoimmunity?

Answer 36

When microbial antigens resemble self-antigens, leading to autoimmunity.

Question 37

What is the role of dendritic cells in T cell activation?

Answer 37

They capture and present antigens to naïve T cells.

Question 37

What is the key difference between a live-attenuated and inactivated vaccine?

Answer 37

Live-attenuated vaccines use weakened pathogens; inactivated vaccines use killed pathogens.

Question 38

What is the role of Toll-like receptors (TLRs) in immunity?

Answer 38

They recognize pathogen-associated molecular patterns (PAMPs) and activate immune responses.

Question 39

Why do infants rely on passive immunity early in life?

Answer 39

Their adaptive immune system is underdeveloped, so they receive maternal IgG and IgA.

Question 40

What is immune exhaustion?

Answer 40

A state where chronic infections cause T cells to lose function.

Question 41

Why do secondary immune responses generate more IgG than IgM?

Answer 41

Due to memory B cell activation and class switching.

Question 42

What is the significance of the germinal center in lymph nodes?

Answer 42

It is where B cells undergo somatic hypermutation and class switching.

Question 43

Why does immune tolerance break down in autoimmunity?

Answer 43

Due to genetic mutations, infections, or environmental triggers.

Question 44

How do MHC molecules contribute to transplant rejection?

Answer 44

Mismatched MHC molecules trigger immune responses against transplanted tissue.

Question 45

What is immune privilege?

Answer 45

Certain tissues (brain, eye, testis) avoid immune attacks to prevent damage.

Question 46

What are regulatory B cells (Bregs)?

Answer 46

They suppress excessive immune responses and maintain tolerance.

Question 47

How does cancer immunotherapy work?

Answer 47

It enhances the immune system's ability to target and destroy tumors.

Question 48

Why do elderly individuals have weaker immune responses?

Answer 48

Due to thymic involution, reduced T cell diversity, and weakened memory responses.