Naturally occurring antibodies devoid of light chains.
Random association of VL and VH repertoires contributes considerably to antibody diversity. The diversity and the affinity are then increased by hypermutation in B cells located in germinal centres. Except in the case of 'heavy chain' disease, naturally occurring heavy-chain antibodies have not been described, although antigen binding has been demonstrated for separated heavy chains or cloned VH domains. Here we investigate the presence of considerable amounts of IgG-like material of M(r) 100K in the serum of the camel (Camelus dromedarius). These molecules are composed of heavy-chain dimers and are devoid of light chains, but nevertheless have an extensive antigen-binding repertoire, a finding that calls into question the role of light chains in the camel. Camel heavy-chain IgGs lack CH1, which in one IgG class might be structurally replaced by an extended hinge. Heavy-chain IgGs are a feature of all camelids. These findings open new perspectives in the engineering of antibodies.
Hamers-Casterman
C
C
Vrije Universiteit Brussel, Instituut voor Moleculaire Biologie, Belgium.
Atarhouch
T
T
Muyldermans
S
S
Robinson
G
G
Hamers
C
C
Songa
E B
EB
Bendahman
N
N
Hamers
R
R
D000595:Amino Acid Sequence; D000818:Animals; D000953:Antigens, Protozoan / Q000276:immunology; D001483:Base Sequence; D002162:Camelus / Q000276:immunology*; D004277:DNA, Single-Stranded; D006801:Humans; D007127:Immunoglobulin Constant Regions / Q000235:genetics; D007074:Immunoglobulin G / Q000145:classification; D007143:Immunoglobulin Heavy Chains / Q000097:blood* / Q000737:chemistry / Q000235:genetics / Q000276:immunology; D007135:Immunoglobulin Variable Region / Q000235:genetics; D008969:Molecular Sequence Data; D011487:Protein Conformation; D017386:Sequence Homology, Amino Acid; D014352:Trypanosomiasis / Q000276:immunology / Q000662:veterinary
D000953:Antigens, Protozoan; D004277:DNA, Single-Stranded; D007127:Immunoglobulin Constant Regions; D007074:Immunoglobulin G; D007143:Immunoglobulin Heavy Chains; D007135:Immunoglobulin Variable Region