Antibodies to the desmoglein 1 precursor proprotein but not to the mature cell surface protein cloned from individuals without pemphigus.
In pemphigus foliaceus (PF), autoantibodies against desmoglein 1 (Dsg1) cause blisters. Using Ab phage display, we have cloned mAbs from a PF patient. These mAbs, like those from a previous patient, were directed against mature Dsg1 (matDsg1) on the cell surface of keratinocytes and precursor Dsg1 (preDsg1) in the cytoplasm. To determine whether individuals without pemphigus have B cell tolerance to Dsg1, we cloned mAbs from two patients with thrombotic thrombocytopenic purpura and a healthy person. We found mAbs against preDsg1, but not matDsg1. All but 1 of the 23 anti-preDsg1 mAbs from PF patients and those without PF used the VH3-09 (or closely related VH3-20) H chain gene, whereas no PF anti-matDsg1 used these genes. V(H) cDNA encoding anti-preDsg1 had significantly fewer somatic mutations than did anti-matDsg1 cDNA, consistent with chronic Ag-driven hypermutation of the latter compared with the former. These data indicate that individuals without PF do not have B cell tolerance to preDsg1 and that loss of tolerance to matDsg1 is not due to epitope shifting of anti-preDsg1 B cells (because of different V(H) gene usage). However, presentation of peptides from Dsg1 by preDsg1-specific B cells may be one step in developing autoimmunity in PF.
Yamagami
Jun
J
Department of Dermatology, University of Pennsylvania, Philadelphia, PA 19104, USA.
Kacir
Stephen
S
Ishii
Ken
K
Payne
Aimee S
AS
Siegel
Don L
DL
Stanley
John R
JR
D000911:Antibodies, Monoclonal / Q000096:biosynthesis / Q000235:genetics; D000918:Antibody Specificity; D001323:Autoantibodies / Q000096:biosynthesis* / Q000235:genetics; D003001:Cloning, Molecular; D051183:Desmoglein 1 / Q000276:immunology* / Q000302:isolation & purification; D006801:Humans; D007108:Immune Tolerance; D008565:Membrane Proteins / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification*; D010392:Pemphigus / Q000276:immunology* / Q000378:metabolism* / Q000473:pathology; D011498:Protein Precursors / Q000037:antagonists & inhibitors / Q000276:immunology* / Q000302:isolation & purification; D011697:Purpura, Thrombotic Thrombocytopenic / Q000276:immunology / Q000378:metabolism
D000911:Antibodies, Monoclonal; D001323:Autoantibodies; C495297:DSG1 protein, human; D051183:Desmoglein 1; D008565:Membrane Proteins; D011498:Protein Precursors