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|Title:||Specificity of Anti-Dna Antibodies in Systemic Lupus Erythematosus|
|Author(s):||Casperson, Gerald Fries|
|Department / Program:||Microbiology|
|Degree Granting Institution:||University of Illinois at Urbana-Champaign|
|Subject(s):||Health Sciences, Immunology|
|Abstract:||In an effort to clarify the involvement of anti-DNA antibodies in the disease systemic lupus erythematosus (SLE), the specificity of naturally occuring anti-DNA antibody in plasma of human patients with SLE was studied in detail.
Colicin E1 plasmid DNA was employed as a test antigen in these studies utilizing an ammonium sulfate precipitation assay. Intact colicin E1 plasmid was shown to be specific for anti-double-stranded DNA (anti-dsDNA) antibodies and did not react with single-stranded DNA (ssDNA) specific antisera. ssDNA test antigen was similarly shown to be specific for anti-ssDNA antibodies and was bound by dsDNA-specific antibodies.
Studies employing ss and dsDNA from calf thymus and mononucleotides as inhibitors of DNA binding demonstrated the presence of two anti-DNA populations in IgG fractions of the plasma tested: Type I--specific for ssDNA, and type II--cross-reactive, binding both ssDNA and dsDNA with apparently equal affinity. The specificity of the cross-reactive population was investigated in greater detail.
ssDNA binding by type II antibodies was less effective at higher temperatures when compared to dsDNA binding, indicating structural and possibly nucleotide specificity. Structural specificity of type II antibodies was confirmed when synthetic double-stranded deoxynucleotide polymers proved to be more effective inhibitors of dsDNA binding than were the substituent single-stranded polymers.
Type II anti-DNA antibodies were shown to interact electrostatically with the deoxyribose-phosphate backbone of DNA as dsDNA binding was sensitive to increasing sodium chloride concentrations.
Recognition of nucleotide bases in dsDNA by type II antibodies was demonstrated by several lines of evidence: (1) Mononucleotides inhibited dsDNA binding while deoxyribose-phosphate did not. (2) One plasma tested (PS) showed specificity for GC rich DNA. (3) Poly(dG)(.)poly(dC) inhibited a different population of anti-DNA antibodies than poly(dA)(.)poly(dT) or poly(dA-dT)(.)poly(dA-dT).
It was concluded that the linear deoxyribose-phosphate backbone, secondary structure, and nucleotide bases of DNA were all important to dsDNA recognition by type II anti-DNA antibodies in SLE plasma, although the relative contribution of each varied from patient to patient.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1982.
|Date Available in IDEALS:||2014-12-16|