Parasitic Zoonoses

• Cytokine Functions in Immunology:
• IL-1: Secreted by macrophages; acts as a (III) Proinflammatory mediator inducing fever, acute-phase proteins, and co-stimulating Th2 development.
• IL-2 (T cell growth factor): Secreted by activated Th1 cells; (I) Stimulates T cell proliferation and cytotoxicity (drives clonal expansion of cytotoxic T cells and NK cells).
• IL-4: Secreted by Th2 cells; (IV) Stimulates growth, activation, and differentiation of B cells, driving immunoglobulin class-switching to IgE and IgG1.
• Interferon-gamma (IFN-$\gamma$): Secreted by Th1 and NK cells; (II) Key mediator of cell-mediated immunity, strongly activating macrophages for intracellular pathogen clearance.
• Matching Result:
• (III), (B)-(I), (C)-(IV), (D)-(II). Hence, Option 2 is correct.

• Immunological Action of Superantigens:
• Conventional peptide antigens must be processed into fragments, fit into the antigen-binding groove of MHC class II molecules, and be recognized by specific TCR complementarity-determining regions (activating $\lt 0.01\%$ of T cells).
• Superantigens (e.g., Staphylococcal enterotoxins, TSST-1):
• Do NOT require processing and do NOT bind inside the MHC groove.
• Instead, they cross-link the outer lateral surface of MHC class II molecules directly to the variable beta ($V\beta$) domain of the T cell receptor (TCR).
• This bypasses antigen specificity, bridging the APC and T cell directly and triggering an uncontrolled, massive polyclonal T cell activation of up to $5 - 20\%$ of all circulating T cells, leading to massive cytokine storms.
• nalysis:
• Both (A) and (R) are correct, and (R) provides the mechanical explanation for (A). Hence, Option 1 is correct.

• Sequential Stages of Erythrocytic Maturation:
• In bone marrow erythropoiesis:

• Rubriblast (Proerythroblast)
• Prorubricyte (Basophilic erythroblast)
• Polychromatophilic rubricyte (B) (hemoglobin synthesis initiates)
• Metarubricyte (C) (normoblast; pyknotic nucleus extrudes)
• Reticulocyte (D) (anucleated cell with residual ribosomal RNA)
  6. Mature Erythrocyte (A) (biconcave red blood corpuscle)
  • Sequence:

• nalysis:
• ((B), (C), (D), (A)): Correct.

Correct option: (3) (B), (C), (D), (A)