Berlin patient A man with HIV who was treated in Berlin with a hematopoietic stem cell (HSC) transplant from a donor deficient in a co-receptor for the virus (CCR5) for an unrelated illness (leukemia). He is thought to be cured of HIV infection, and is one of the only known patients in which the virus is thought to be completely eliminated, a so-called ‘sterilizing’ cure.
biologics therapy Medical treatments comprising natural proteins such as antibodies and cytokines, and antisera or whole cells.
Blau syndrome An inherited granulomatous disease caused by gain-offunction mutations in the NOD2 gene.
BLIMP-1 A transcriptional repressor that promotes B-cell differentiation into plasma cells and suppresses proliferation, and further class switching and affinity maturation.
BLNK B-cell linker protein. See SLP-65.
bone marrow The tissue where all the cellular elements of the blood—red blood cells, white blood cells, and platelets—are initially generated from hematopoietic stem cells. The bone marrow is also the site of further B-cell development in mammals and the source of stem cells that give rise to T cells on migration to the thymus. Thus, bone marrow transplantation can restore all the cellular elements of the blood, including the cells required for adaptive immune responses.
booster immunization See secondary immunization.
bradykinin A vasoactive peptide that is produced as a result of tissue damage and acts as an inﬂammatory mediator.
broadly neutralizing antibodies Antibodies that block viral infection by multiple strains. In reference to HIV, these are antibodies that block binding of the virus to CD4 and/or chemokine co-receptors.
bronchus-associated lymphoid tissue (BALT) Organized lymphoid tissue found in the bronchi in some animals. Adult humans do not normally have such organized lymphoid tissue in the respiratory tract, but it may be present in some infants and children.
Bruton’s tyrosine kinase (Btk) A Tec-family tyrosine kinase important in B-cell receptor signaling. Btk is mutated in the human immunodeficiency disease X-linked agammaglobulinemia.
Bruton’s X-linked agammaglobulinemia See X-linked agammaglobulinemia.
bursa of Fabricius   Lymphoid organ associated with the gut that is the site of B-cell development in chickens.
butyrate A short chain fatty acid produced abundantly by anaerobic digestion of carbohydrates in the intestine by commensals that can inﬂuence host cells in several ways, acting as an energy source for enterocytes and as an inhibitor of histone deacetylases.
C1 complex, C1 Protein complex activated as the first step in the classical pathway of complement activation, composed of C1q bound to two molecules each of the proteases C1r and C1s. Binding of a pathogen or antibody to C1q activates C1r, which cleaves and activates C1s, which cleaves C4 and C2.
C1 inhibitor (C1INH) An inhibitor protein for C1 that binds and inactivates C1r:C1s enzymatic activity. Deficiency in C1INH causes hereditary angioedema through production of vasoactive peptides that cause subcutaneous and laryngeal swelling.
C2 Complement protein of the classical and lectin pathways that is cleaved by the C1 complex to yield C2b and C2a. C2a is an active protease that forms part of the classical C3 convertase C4bC2a.
C3 Complement protein on which all complement activation pathways converge. C3 cleavage forms C3b, which can bind covalently to microbial surfaces, where it promotes destruction by phagocytes.