26:Immunity and the Immune Response

Clonal anergy

the inability to produce an immune response to specific antigens due to neutralization of effector cells

Clonal deletion

the killing of useless or self-reactive T cell clones during thymus selection

Clonal selection

the production by a B or T cell of copies of itself after antigen interaction

Complementarity-determining region (CDR)

a varying amino acid sequence within the variable domains of immunoglobulins or T cell receptors where contacts with antigen are made

Human leukocyte antigen (HLA)

an antigen-presenting protein encoded by the major histocompatibility complex gene in humans

Immunoglobulin gene superfamily

a family of genes evolutionarily and structurally related to immunoglobulins

Motif

in antigen presentation, a conserved amino acid sequence found in peptides that bind a given MHC protein

Negative selection

the deletion of T cells that interact with self antigens in the thymus

Phylogeny

the occurrence of multiple copies of evolutionarily related genes

Polymorphism

the occurrence of multiple alleles for a gene locus in a population at a higher frequency than expected from mutation alone

Positive selection

the growth and development of T cells that interact with self MHC–peptide in the thymus

Somatic hypermutation

the mutation of immunoglobulin genes at rates higher than other genes