Page 507 - Veterinary Immunology, 10th Edition

VetBooks.ir LEARNING OBJECTIVES

After reading this chapter, you should be able to:

• List the major noncovalent bonds that bind antibodies to antigens.
• Explain why the shape of the antigen-binding groove depends on the sequence
of the amino acids that line the groove.

• Describe how V, D, and J genes act together to generate hypervariable antigen-
binding site.
• Explain how an enormous number of different BCRs are generated through the

use of a limited number of genes.
• Explain the generation of variable regions by means of gene recombination.
• Explain the process of gene conversion.

• Explain why the genes coding for antigen-binding sites in BCRs, but not TCRs,
also undergo random somatic mutation.
• Define gene conversion, somatic mutation, gene recombination, base deletion,

receptor editing, and junctional diversity.
• Explain the role of the microbiota in generating immunoglobulin diversity.

• Explain how TCR diversity is generated.
• Explain how the developing T cell produces either γ/δ or α/β antigen receptors.

Because bacteria and viruses have a short generation time, they
have the ability to mutate and change rapidly. As a result, the
immune system must be able to respond not only to existing

organisms but also, within reason, to newly evolved organisms. The
ability of the adaptive immune responses to respond specifically to
an enormous number of foreign antigens implies the existence of an

enormous number of lymphocytes, each with its own specific
antigen receptors. This then raises the question, how do
lymphocytes generate such an enormous diversity of these
receptors?
The ability of a receptor to bind an antigen is determined by the

shape of its binding site. This shape depends on the folding of its
peptide chains, which is governed, in turn, by their amino acid
sequences. Each amino acid in a peptide chain exerts an influence

on its neighboring amino acids, which determines their relative

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