Immunology: Which of the following statements about antigen epitopes (antigenic determinants) is incorrect?

Introduction:
Epitopes are the specific structural features on antigens recognized by immune receptors. Understanding who recognizes what—B cells, antibodies, or T cells—is fundamental. This question asks you to identify the incorrect statement regarding epitope recognition patterns.

Given Data / Assumptions:

• B-cell receptors (BCRs) and antibodies bind native, accessible structures (proteins, polysaccharides, lipids).
• T-cell receptors (TCRs) recognize peptides presented on MHC after antigen processing.
• Antigens often display many epitopes; cross-reactivity can occur when epitopes are shared.

Concept / Approach:
Antibody/BCR recognition favors native surface topologies (conformational or linear). T cells require processing into peptides and presentation by MHC. Therefore, the claim that B cells bind only processed epitopes is incorrect because it reverses the roles of B cells and T cells.

Step-by-Step Solution:

Verification / Alternative check:
Experimental approaches (e.g., ELISA with native antigens) demonstrate antibody binding without antigen processing, while T-cell assays require peptide–MHC presentation, validating the distinction.

Why Other Options Are Wrong:

• Shared epitopes and multiple epitopes per antigen: well established.
• Linear vs conformational epitopes: standard classification.
• T-cell recognition of peptide–MHC: core tenet of adaptive immunity.

Common Pitfalls:
Confusing epitope types seen by B cells vs T cells or assuming all recognition requires processing.

Final Answer:
B cells bind only processed (peptide-presented) epitopes and never native structures.