What is the primary function of anaphylotoxins (e.g., C3a, C4a, C5a) in the immune system?

Correct Answer: C

Rationale: The correct answer is C: Inducing inflammation and recruiting immune cells. Anaphylotoxins, such as C3a, C4a, and C5a, are small molecules that are released during complement activation. They play a crucial role in enhancing inflammation by attracting immune cells to the site of infection or injury. 1. Anaphylotoxins induce inflammation by stimulating the release of histamine and other inflammatory mediators. 2. They promote vasodilation and increase vascular permeability, allowing immune cells to easily reach the affected area. 3. Anaphylotoxins also act as chemoattractants, recruiting neutrophils, macrophages, and other immune cells to the site of inflammation to help fight against pathogens. 4. These molecules do not suppress inflammation (choice A), facilitate antigen presentation (choice B), or neutralize pathogens (choice D). Their primary function is to amplify the immune response by inducing inflammation and recruiting immune cells to combat infections

Correct Answer: B

Rationale: The correct answer is B: Affinity maturation. During a secondary immune response, B cells undergo somatic hypermutation, leading to the production of antibodies with higher affinity for the antigen. This process occurs in germinal centers within secondary lymphoid organs. Isotype switching (A) refers to the change in antibody class but not affinity. Somatic recombination (C) is the process of creating diverse antibody repertoires. Clonal expansion (D) involves the proliferation of antigen-specific B cells but does not directly address affinity enhancement.

Correct Answer: B

Rationale: The correct answer is B: Helper T cells. Helper T cells play a crucial role in activating B cells by releasing cytokines that stimulate B cell proliferation and differentiation into plasma cells, which produce antibodies. Cytotoxic T cells (A) are involved in directly killing infected cells. Regulatory T cells (C) suppress immune responses. Memory T cells (D) are responsible for maintaining immunological memory for future responses. Thus, Helper T cells are the key cell type that helps activate B cells.

Correct Answer: C

Rationale: Regulatory T cells (Tregs) maintain immune homeostasis by suppressing immune responses using IL-10. Tregs release IL-10, which inhibits the activity of effector T cells and other immune cells, preventing excessive immune responses and maintaining balance. This mechanism helps prevent autoimmune diseases and chronic inflammation. Choices A, B, and D are incorrect because Tregs do not kill infected cells, produce pro-inflammatory cytokines, or activate macrophages. Instead, Tregs focus on regulating and dampening immune responses to maintain overall immune balance.

Correct Answer: B

Rationale: The correct answer is B: Goodpasture's syndrome. This disease is specifically associated with autoantibodies targeting type IV collagen in the basement membranes of the kidneys and lungs, leading to glomerulonephritis and pulmonary hemorrhage. Sarcoidosis (A) involves non-caseating granulomas, not collagen autoantibodies. Systemic lupus erythematosus (SLE) (C) is associated with various autoantibodies but not specifically targeting type IV collagen. Rheumatoid arthritis (D) is characterized by autoantibodies against citrullinated peptides and synovial tissue, not type IV collagen.