Immune System Practice Test 2026 - Free Immune System Practice Questions and Study Guide

The key idea is that adaptive immunity is driven by lymphocytes. These white blood cells—B cells and T cells—are specialized to recognize specific antigens, expand clonally when they encounter them, and form memory cells so the body responds faster upon re-exposure. B cells become plasma cells that secrete antibodies, which are important effectors of the adaptive response, but antibodies are produced by lymphocytes rather than being the primary driving agents themselves. T cells carry out direct attacks on infected cells and help coordinate the overall response. Macrophages and neutrophils belong to innate immunity and provide early, non-specific defense; they can also present antigens to lymphocytes, but they’re not the principal agents of the adaptive response.