Answer: Oxidative burst (NADPH oxidase producing superoxide), MPO (hypochlorous acid from H2O 2 + Cl-), defensins, and elastase.
- A Mainly physical engulfment of the bacterium by the cell's plasma membrane folding largely around it under typical conditions
- B Oxidative burst (NADPH oxidase producing superoxide), MPO (hypochlorous acid from H2O<sub>2</sub> + Cl-), defensins, and elastase
- C Mainly degranulation of preformed granules releasing their antimicrobial contents alone each time according to standard textbooks
- D Mainly T cell activation by helper cells, with little role for neutrophils themselves in the process in general practice
Correct answer: B. Oxidative burst (NADPH oxidase producing superoxide), MPO (hypochlorous acid from H2O<sub>2</sub> + Cl-), defensins, and elastase
Explanation: Neutrophil killing: phagocytosis + NADPH oxidase oxidative burst (O<sub>2</sub>- → H2O<sub>2</sub>) + myeloperoxidase (H2O<sub>2</sub> + Cl- → HOCl) + defensins (membrane disruption) + proteases (elastase, cathepsins).
An antibody is Y-shaped, with two identical antigen-binding sites at the tips of the variable regions - each shaped to recognise one specific antigen - while the constant (Fc) region at the base is recognised by immune cells to trigger further responses.
Concept context
Innate and adaptive immunity, B cells, T cells, antibodies, vaccines, and immune disorders. Critical for NEET.