Objectives:In an ongoing effort to identify diagnostic ovarian cancer biomarkers,SEREX (serological analysis of recombinant cDNA expression libraries) technique was employed resulting in detection of 20 known genes,nine ESTs and one novel sequence. Interleukin-8 (IL-8) was one of ovarian cancer-associated antigens identified by SEREX screening. The objective of this study was,therefore,to evaluate the potential importance of circulating anti-IL-8 antibody as ovarian cancer biomarker. Methods:We developed and optimized a new immunofluorescent bead-based assay for detection of anti-IL-8 antibody in blood serum. Circulating IL-8 and anti-IL-8 IgG concentrations were measured in blood sera from 44 patients with early stage (I-II) ovarian cancer,50 patients with late stage (III-IV) ovarian cancer,37 patients with benign pelvic masses,and 80 healthy women using the bead-based assay. Results:Our data indicate that serum contains IL-8 cytokine,anti-IL-8 antibody,and IL-8:anti-IL-8 complexes. We found that concentrations of IL-8 and anti-IL-8 antibody were elevated in sera of patients with ovarian cancer as compared with healthy controls. Logistic regression analysis of circulating concentrations of anti-IL-8 IgG in patients with stages I-II ovarian cancer versus healthy controls allowed for prediction of early ovarian cancer with 98%specificity,65.5%sensitivity,80.3%of patients correctly classified. Combining IL-8 and anti-IL-8 IgG with CA 125 resulted in increased classification power as compared to individual markers analyzed separately. Conclusion:Thus,IL-8 and anti-IL-8 autoantibody might potentially serve as additional biomarkers for ovarian cancer. Objectives: In an ongoing effort to identify diagnostic ovarian cancer biomarkers, SEREX (serological analysis of recombinant cDNA expression libraries) technique was employed in detection of 20 known genes, nine ESTs and one novel sequence. Interleukin-8 (IL-8) was one of ovarian cancer-associated antigens identified by SEREX screening. The objective of this study was, therefore, to evaluate the potential importance of circulating anti-IL-8 antibody as ovarian cancer biomarker. Methods: We developed and optimized a new immunofluorescent bead- based assay for detection of anti-IL-8 antibody in blood serum. Circulating IL-8 and anti-IL-8 IgG concentrations were measured in blood sera from 44 patients with early stage (I-II) 37 (3-IV) ovarian cancer, 37 patients with benign pelvic masses, and 80 healthy women using the bead-based assay. Results: Our data indicates that the serum contains IL-8 cytokine, anti-IL- 8: anti-IL-8 complexes. W e found that concentrations of IL-8 and anti-IL-8 antibody were elevated in sera of patients with ovarian cancer as compared with healthy controls. Logistic regression analysis of circulating concentrations of anti-IL-8 IgG in patients with stages I-II ovarian cancer versus healthy controls allowed for prediction of early ovarian cancer with 98% specificity, 65.5% sensitivity, 80.3% of patients correctly classified. Combining IL-8 and anti-IL-8 IgG with CA 125 resulted in increased classification power as compared to individual: Figures derived separately. Conclusion: Thus, IL-8 and anti-IL-8 autoantibs might potentially serve as additional biomarkers for ovarian cancer.