Rheumatoid factor autoantibody-binding site: a molecular analysis using monoclonal antibodies with dual anti-TNP and anti-IgG activities.
Two out of five murine IgG3 anti-trinitrophenyl (TNP) monoclonal antibodies (mAb) obtained either by immunization with TNP-keyhole limpet hemocyanin (KLH) (CB1, CB5, CB6 and 4H10) or with dinitrophenyl-lipopolysaccharide (9A6), exhibited anti-IgG rheumatoid factor (RF) activity (CB6 and 4H10). The anti-IgG activity of these two anti-TNP RF was specifically inhibited by murine IgG as well as by the hapten TNP. In order to identify the structural basis for the anti-IgG activity, the nucleotide sequences encoding the VH and VL regions were determined. By comparing the V regions of the non-RF and RF anti-TNP mAb, it was found that one anti-TNP RF antibody, CB6, shares virtually identical VL and VH regions with two anti-TNP antibodies, CB1 and CB5, but markedly differs from these in the D region. Furthermore, the light chain framework region 2 (FR2) and FR3 of non-RF mAb, CB1, CB5 and 9A6, have amino acid sequences almost identical to those claimed for anti-IgG1 RF activity (Shlomchik et al., J. Exp. Med. 1986. 164: 407). Our findings suggest, at least in the case of CB6 mAb, the involvement of CDR, but not light chain FR residues, in IgG binding.
Reininger
L
L
Department of Pathology, Medical Center of The University of Geneva, Switzerland.
Spertini
F
F
Shibata
T
T
Jaton
J C
JC
Izui
S
S
D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D001323:Autoantibodies / Q000235:genetics / Q000276:immunology*; D001483:Base Sequence; D001666:Binding Sites, Antibody; D007143:Immunoglobulin Heavy Chains / Q000502:physiology; D007147:Immunoglobulin Light Chains / Q000502:physiology; D007135:Immunoglobulin Variable Region / Q000235:genetics* / Q000502:physiology; D051379:Mice; D008815:Mice, Inbred Strains; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000235:genetics; D012217:Rheumatoid Factor / Q000235:genetics / Q000276:immunology*; D014301:Trinitrobenzenes / Q000276:immunology
D000911:Antibodies, Monoclonal; D001323:Autoantibodies; D007143:Immunoglobulin Heavy Chains; D007147:Immunoglobulin Light Chains; D007135:Immunoglobulin Variable Region; D012333:RNA, Messenger; D014301:Trinitrobenzenes; D012217:Rheumatoid Factor