Human monoclonal Fab fragments recovered from a combinatorial library bind specifically to the platelet HPA-1a alloantigen on glycoprotein IIb-IIIa.

Abstract

BACKGROUND AND OBJECTIVES:

Certain clinical conditions are related to the presence of platelet-specific alloantibodies in the patient's serum. We studied the molecular diversity of HPA-1a antibodies to analyze some peculiarities of this antibody response.

MATERIALS AND METHODS:

Human antibody Fab fragments that bind to the platelet alloantigen HPA-1a on glycoprotein IIb-IIIa (GPIIbIIIa) were generated by using a recombinant phage display system. We established an immunoglobulin G1, kappa combinatorial library from the peripheral blood lymphocytes of a person undergoing a severe posttransfusion purpura.

RESULTS:

Characterization of Fab clones selected from the fifth round of antigen-specific panning of this library demonstrates a highly specific reactivity to the HPA-1a alloantigen. The nucleotide sequence analysis of representative HPA-la-specific clones reveals at least 3 distinct V1 and 3VH gene segments that present an extensive degree of mutation as demonstrated by comparison of gene usage and homologies to the nearest germline genes.

CONCLUSIONS:

These human HPA-la-specific Fab reagents should allow us to better understand the molecular mechanism involved in HPA-la alloimmunization.

• Authors: C Proulx, P Chartrand, V Roy, M Goldman, F Décary, A Rinfret
• Journal: Vox sanguinis (Vox Sang) Vol. 72 Issue 1 Pg. 52-60 ( 1997) ISSN: 0042-9007 [Print] England
• PMID: 9031502 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Antibodies, Monoclonal
• Antigens, Human Platelet
• Epitopes
• ITGB3 protein, human
• Immunoglobulin Fab Fragments
• Integrin beta3
• Peptide Library
• Platelet Glycoprotein GPIIb-IIIa Complex

Topics

• Amino Acid Sequence
• Antibodies, Monoclonal (immunology)
• Antigens, Human Platelet (immunology)
• Blood Platelets (immunology)
• Epitopes
• Humans
• Immunoglobulin Fab Fragments (genetics, immunology)
• Integrin beta3
• Molecular Sequence Data
• Peptide Library
• Platelet Glycoprotein GPIIb-IIIa Complex (immunology)