Q: Which equation best represents the calculation of antibody titer in a serum sample?

$$\text{Antibody Titer} = \frac{\text{Highest dilution showing positive reaction}}{1}$$

Question 1

Which of the following best describes the difference between humoral and cellular immunity?

Accepted Answer

Humoral immunity involves antibodies produced by B cells and responds to antigens in body fluids, while cellular immunity involves T cells and responds to intracellular antigens.

Question 2

A patient receives an injection of antiserum containing antibodies against rabies. Which type of adaptive immunity is this?

Accepted Answer

Artificially acquired passive immunity

Question 3

Which immunoglobulin class is most prevalent in serum and is responsible for neutralizing bacterial toxins, complement fixation, and enhancing phagocytosis?

Accepted Answer

IgG

Question 4

A hapten is unable to stimulate antibody production unless it is attached to a carrier molecule. However, once antibodies are formed, haptens can react with them independently. Which scenario best illustrates this concept?

Accepted Answer

A small drug molecule binds to a protein in the blood, forming a complex that triggers an allergic reaction. Later, the drug alone can bind to the antibodies formed.

Question 5

Which of the following statements about cytokines is correct?

Accepted Answer

Interleukins (IL) are cytokines that serve as communicators between leukocytes.

Question 6

During the primary immune response, the peak IgG titer occurs after how many days following exposure to an antigen?

Accepted Answer

10–17 days

Question 7

Which process enhances phagocytosis by coating antigens with antibodies?

Accepted Answer

Opsonization

Question 8

A child receives immunity from antibodies passed through colostrum while breastfeeding. This is an example of:

Accepted Answer

Naturally acquired passive immunity

Question 9

Which of the following cells are classified as antigen-presenting cells (APCs)?

Accepted Answer

B cells, dendritic cells, and macrophages

Question 10

Which immunoglobulin class is primarily involved in allergic reactions and defense against parasitic worms?

Accepted Answer

IgE

Question 11

A patient develops a cytokine storm after an infection. Which of the following best describes the consequence of this event?

Accepted Answer

Tissue damage due to overproduction of cytokines

Question 12

Which equation best represents the calculation of antibody titer in a serum sample?

Accepted Answer

$$	ext{Antibody Titer} = \frac{	ext{Highest dilution showing positive reaction}}{1}$$

Question 13

Which of the following is TRUE regarding the activation of cytotoxic T lymphocytes (CTLs)?

Accepted Answer

CTLs are activated by antigens synthesized in infected cells and presented with MHC class I molecules.

Question 14

Which immunoglobulin class is a pentamer and is involved in agglutination and complement fixation?

Accepted Answer

IgM

Question 15

A person is exposed to an antigen for the second time. Which cells are primarily responsible for the rapid and robust secondary immune response?

Accepted Answer

Memory cells

Question 16

Which of the following best describes the function of T regulatory cells (Treg)?

Accepted Answer

Suppress T cells against self to prevent autoimmunity

Question 17

Which process occurs when an antibody binds to epitopes on two different cells, resulting in clumping?

Accepted Answer

Agglutination

Question 18

Which of the following is a correct sequence for the activation of B cells by T-dependent antigens?

Accepted Answer

B cell binds antigen → internalizes antigen → presents antigen with MHC II → TH cell activates B cell

Question 19

Which of the following cells lyse virus-infected cells, tumor cells, and parasites, especially those that do not express MHC class I antigens?

Accepted Answer

Natural killer (NK) cells

Adaptive Immunity: Mechanisms and Components

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