A novel anti-microfilament antibody, anti-135 kD, is associated with Raynaud's disease, undifferentiated connective tissue disease and systemic autoimmune diseases.
We report herein the characterization of a human IgG antibody reactive with a nonmuscle 135 kD microfilament-associated protein, anti-135 kD. Using nonmuscle epithelial PtK2 cells as substrate in indirect immunofluorescence, we identified a distinctive pattern of reactivity with microfilaments in sera from 12 of 165 (7.3%) patients investigated for systemic autoimmune diseases and in only 2 of 171 (1.2%) normal and rheumatic disease controls (P < 0.006, 95% Cl 1.46 to 30.1). An association between anti-135 kD and Raynaud's phenomenon (n = 12/14, 85.7%) with or without an associated systemic autoimmune disease was noted. The anti-135 kD specificity was established by several criteria. (1) The fluorescence was periodically distributed along microfilaments and concentrated at focal adhesions for all sera (n = 14). (2) On immunoblots, the 14 sera reacted with a PtK2 polypeptide of 135 kD. (3) IgG purified by blot-affinity from the 135 kD band (alpha-135) reproduced the fluorescent pattern of the original sera while IgG purified from other bands did not. (4) Double immunofluorescence with alpha-135 and anti-alpha-actinin mAb indicated absence of antibody fluorescence at ruffling membranes where a-actinin was distributed. (5) IgG subclass analysis of anti-135 kD revealed that 12 (85.7%) sera are of IgG3 isotype and 2 (14.3%) are of IgG1 isotype while the light chain expression was kappa restricted. This is the first report of an antibody to a 135 kD microfilament protein. Anti-135 kD expand the repertoire of anti-microfilament and anticytoskeletal antibodies in human sera.
Girard
D
D
Department of Medicine, University of Montréal School of Medicine and Hôpital Notre-Dame, Québec, Canada.
Senécal
J L
JL
D000328:Adult; D000368:Aged; D000915:Antibody Affinity / Q000276:immunology; D001323:Autoantibodies / Q000737:chemistry*; D001327:Autoimmune Diseases / Q000276:immunology* / Q000473:pathology; D002478:Cells, Cultured; D003240:Connective Tissue Diseases / Q000276:immunology* / Q000473:pathology; D005260:Female; D019084:Fluorescent Antibody Technique, Indirect; D006801:Humans; D015151:Immunoblotting; D007074:Immunoglobulin G / Q000737:chemistry / Q000145:classification; D008297:Male; D008840:Microfilament Proteins / Q000276:immunology*; D008875:Middle Aged; D008970:Molecular Weight; D011928:Raynaud Disease / Q000276:immunology*
D001323:Autoantibodies; D007074:Immunoglobulin G; D008840:Microfilament Proteins