Characterization of monoclonal anti-beta2-glycoprotein-I and anti-prothrombin antibody fragments generated by phage display from a patient with primary antiphospholipid syndrome.
The molecular structure of antibodies associated with autoimmune thrombosis is beginning to be understood. We describe the binding specificities and sequence analysis of anti-beta2-glycoprotein-I (anti-beta2GP-I) or anti-prothrombin (anti-PT) antibody fragments generated by phage display from a patient with primary antiphospholipid syndrome (APS). We obtained 39 positive clones, two that had the correct size reacted with beta2GP-I (Beta 1 and Beta 2). Ten clones with the same restrictive pattern recognized PT (Prot 1) and cross-reacted with beta2GP-I. All three clones recognized anionic and zwitterionic phospholipids. The V(H) regions of both anti-beta2GP-I clones are members of the VH4 family. Prot 1 has a V(H) segment of the VH3 family. The Beta 1 J(H) segments are J(H)5b and J(H)4b for Beta 2 and Prot 1. V(L) genes are V(lambda)1, 3 and 1, respectively. No J(L) was identified for Beta 1, while Beta 2 and Prot 1 carry J(lambda)3b genes. Beta 1 and Beta 2 carry highly conserved germ-line V(H) and V(L) genes. Mutations of the Prot 1 gene appear to be antigen-dependent, most are hotspot mutations located in the CDR 1 and 2 regions. Our work suggests that some anti-beta2GP-I from patients with primary APS are natural autoantibodies. Our work may also help to explain the frequent coexistence of anti-beta2GP-I and anti-PT in the same patient.
Languren
Marisol
M
Department of Immunology and Rheumatology, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán, Vasco de Quiroga 15, 14000 Mexico City, Mexico.
Becerril
Baltazar
B
Cabral
Antonio R
AR
Fernández-Altuna
Luisa E
LE
Pascual
Virginia
V
Hernández-Ramírez
Diego F
DF
Cabiedes
Javier
J
D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000911:Antibodies, Monoclonal / Q000737:chemistry* / Q000235:genetics; D000918:Antibody Specificity; D016736:Antiphospholipid Syndrome / Q000276:immunology*; D017124:Conserved Sequence; D006023:Glycoproteins / Q000276:immunology*; D006801:Humans; D007135:Immunoglobulin Variable Region / Q000737:chemistry / Q000235:genetics; D008969:Molecular Sequence Data; D009154:Mutation; D019151:Peptide Library; D010743:Phospholipids / Q000276:immunology; D011516:Prothrombin / Q000276:immunology*; D053482:beta 2-Glycoprotein I
D000911:Antibodies, Monoclonal; D006023:Glycoproteins; D007135:Immunoglobulin Variable Region; D019151:Peptide Library; D010743:Phospholipids; D053482:beta 2-Glycoprotein I; D011516:Prothrombin