Autoantibodies to decondensed sperm nuclear deoxyribonucleic acid in patients with antisperm antibodies and systemic lupus erythematosus detected by immunofluorescence flow cytometry

Abstract

To evaluate a flow cytometric method to detect and quantitate serum anti-DNA antibodies using unfixed, swollen and decondensed human sperm nuclei and to examine the relationship between antibodies against sperm surface antigens to the presence of antibodies against nuclear antigens. Serum IgG and IgG subclass antibodies to decondensed sperm nuclei were detected by indirect immunofluorescence (IIF) flow cytometry. Sera were screened by IIF for anti-double-stranded DNA antibodies using the protozoan Crithidia luciliae as the substrate and for antinuclear antibodies using human epithelial (HEp 2) cells, respectively. All sera were assessed for antibodies against the sperm plasma membrane by an indirect immunobead test. Infertility laboratory at the University of Oklahoma Health Sciences Center and rheumatology laboratory at the Oklahoma Medical Research Foundation. Sera from 33 antisperm antibody-positive patients (5 subgroups), 33 patients with systemic lupus erythematosus (SLE; 6 subgroups), and 20 normal controls were selected. IgG antibodies against decondensed sperm nuclear DNA were detected in 11 (33.3%) of 33 antisperm antibody-positive patients versus 14 (42.4%) of 33 patients with SLE. Anti-DNA antibodies were most prevalent in vasectomized men and in antisperm antibody positive women with SLE. In the sera from patients with SLE, the presence of the anti-nuclear ribonucleoprotein antibody was associated with the presence of sperm head-directed antisperm antibodies. Anti-double-stranded DNA antibodies were found in 6 (18.1%) of 33 sera from patients with antisperm antibody and 17 (51.5%) of 33 sera from patients with SLE. Antinuclear antibodies were found in only 9 (27.2%) of 33 sera from patients with antisperm antibody and 30 (90.9%) of 33 sera from patients with SLE. All 20 of the control sera gave negative results in the three tests. Serum IgG reactivity to sperm nuclei was predominantly of the IgG1 and IgG3 subclasses. Anti-DNA is frequently found in either patients with antisperm antibodies or patients with SLE. Our results indicated that decondensed sperm nuclei can provide a specific substrate for screening serum anti-DNA antibodies.