Scl-70 antigen stability and its effect on antibody detection in scleroderma.
We examined 38 patients with scleroderma, 10 with systemic lupus and 10 normal subjects for Scl-70 antibodies by the gel precipitation and by the immunoblot methods. Increased incidence of Scl-70 antibodies in scleroderma were found by the immunoblot method (55%) compared to the gel precipitation methods (40 or 42% depending on the test kits used). Immunoblot analysis of the antigen prepared with 4.0 M NaCl extraction of rabbit thymus acetone powder revealed antigen to be 100, 86, 80 and 70 kDa. However, mainly a single band of 70 kDa was obtained upon extraction of rabbit thymus with 0.3 M NaCl and of calf thymus antigen. Our data support the suggestion that different molecular species of the Scl-70 antigen have variable binding affinities to nuclear DNA. We suggest that the presence of various molecular forms of the antigen may be a result of this differential binding affinity to DNA and the partial proteolytic digestion of 100 kDa from the antigen as reported by others.
Kumar
V
V
Ernest Witebsky Center for Immunology, Department of Microbiology, SUNY, Buffalo 14214.
Kowalewski
C
C
Koelle
M
M
Qutaishat
S
S
Chorzelski
T P
TP
Beutner
E H
EH
Jarzabek-Chorzelska
M
M
Kolacinska
Z
Z
Jablonska
S
S
D000328:Adult; D000974:Antibodies, Antinuclear / Q000032:analysis*; D000915:Antibody Affinity; D000940:Antigenic Variation; D004264:DNA Topoisomerases, Type I; D005260:Female; D006801:Humans; D015151:Immunoblotting; D005779:Immunodiffusion; D008180:Lupus Erythematosus, Systemic / Q000276:immunology; D008297:Male; D008875:Middle Aged; D008970:Molecular Weight; D009687:Nuclear Proteins / Q000032:analysis*; D012595:Scleroderma, Systemic / Q000276:immunology*
D000974:Antibodies, Antinuclear; D009687:Nuclear Proteins; C048100:Scl 70 antigen, human; D004264:DNA Topoisomerases, Type I