Free APMLE Immunology Questions and Answers — Questions and Answers
Question 1: Which immune cells are primarily responsible for producing antibodies?
- T cells
- Natural killer cells
- Macrophages
- B cells (Correct answer)
Correct answer: B cells
B cells, or B lymphocytes, are a critical component of the adaptive immune system. Upon activation by specific antigens, they differentiate into plasma cells, which are specialized cells responsible for producing and secreting large quantities of antibodies (immunoglobulins). These antibodies then target and neutralize specific pathogens or toxins.
Question 2: Which class of immunoglobulin is the first to be produced during an initial immune response?
- IgA
- IgG
- IgE
- IgM (Correct answer)
Correct answer: IgM
Immunoglobulin M (IgM) is the first class of antibody produced and secreted by plasma cells during the primary immune response to a new antigen. Its pentameric structure allows it to efficiently bind to multiple antigens, making it highly effective at activating the complement system and agglutinating pathogens early in an infection.
Question 3: What is the primary function of the major histocompatibility complex (MHC)?
- Produce cytokines
- Present antigens to T cells (Correct answer)
- Activate B cells
- Neutralize toxins
Correct answer: Present antigens to T cells
The Major Histocompatibility Complex (MHC) molecules are cell surface proteins crucial for the adaptive immune system. Their primary function is to bind and present fragments of antigens (peptides) to T cells. This presentation allows T cells to recognize and respond to foreign invaders or abnormal self-cells, initiating an immune response.
Question 4: Which type of hypersensitivity reaction is mediated by IgE?
- Type I (Correct answer)
- Type II
- Type III
- Type IV
Correct answer: Type I
Type I hypersensitivity reactions, also known as immediate hypersensitivity or allergic reactions, are mediated by IgE antibodies. Upon re-exposure to an allergen, IgE antibodies bound to mast cells and basophils trigger the release of histamine and other inflammatory mediators, leading to rapid symptoms like hives, asthma, or anaphylaxis.
Question 5: What is the role of cytokines in the immune system?
- Neutralize bacterial toxins
- Facilitate communication between immune cells (Correct answer)
- Present antigens to T cells
- Destroy infected host cells
Correct answer: Facilitate communication between immune cells
Cytokines are a diverse group of small proteins that act as chemical messengers in the immune system. They are secreted by various immune cells and play a crucial role in regulating immune responses. By facilitating communication, cytokines coordinate cell activities, and influence cell growth, differentiation, and migration to effectively combat pathogens.
Free APMLE Immunology Questions and Answers
Which immune cells are primarily responsible for producing antibodies?