The investigation of autoantibodies which may play a role in the processes of angiogenesis and tumorogenesis is important in the early diagnostis of cancer. This study aimed to investigate the levels of autoantibodies to Glu-plasminogen (Pg) in plasma of patients with tumors. Plasma samples from healthy volunteers were compared with samples from patients with prostate cancer using 2D electrophoresis and MALDI-TOF mass spectrometry. Plasma samples from 25 patients with prostate cancer, 15 patients with benign prostatic hyperplasia (BPH), 29 patients with breast cancer, and 43 healthy volunteers were tested using ELISA to anti-Pg IgG autoantibodies. Affinity chromatography on Pg-sepharoses was used to assess the quantity of anti-Pg IgG in control plasma and plasma of prostate cancer patients. ATTESTAT program was used for nonparametric analysis. Using 2D electrophoresis, marker spots below 50 kD were detected in prostate cancer samples. These spots were identified as fragments of Pg and IgG. Using affinity chromatography on Pg-sepharose, the quantity of IgG bound to Pg versus total IgG was determined to be 9% in control and 27% in prostate cancer samples. The frequency of occurence of elevated levels of anti-Pg IgG was 84% in prostate cancer samples, 69% in breast cancer samples, 40% in BPH samples, and 11% in healthy plasma. Autoantibodies to Pg may be involved in tumorogenesis and elevated levels of anti-Pg IgG antibodies may be a risk factor for tumor development.

(1) Background: The components of the fibrinolytic system and its main component, plasminogen, play a key role in the first months of pregnancy. The effect of autoantibodies interacting with plasminogen in the formation of retrochorial hematoma is unknown. The aim of our study was to determine the role of plasminogen and IgA, IgM, and IgG, which bind to plasminogen, in retrochorial hematoma. (2) Methods: Prothrombin time (PT), thrombin time (TT), partial activated thromboplastin time (aPTT), soluble fibrin-monomer complex (SFMC), D-dimer, plasminogen activity (%Plg), plasminogen concentration (Plg), and the levels of IgG (IgG-Plg), IgM (IgM-Plg), IgA (IgA-Plg) interacting with plasminogen were determined in plasma samples of 57 women with normal pregnancy and 16 with retrochorial hematoma. (3) Results: %Plg in plasma samples from women with retrochorial hematoma was significantly lower than in plasma samples from women with normal pregnancy. The diagnostic significance of %Plg in the ROC analysis was AUC = 0.85. A direct correlation was found between aPTT and the level of autologous IgM interacting with plasminogen. (4) Conclusions: A decrease in the activity of plasminogen in the blood serum of women in the first trimester of pregnancy may indicate disturbances in the hemostasis system and the formation of retrochorial hematoma. According to the results of the study, it is possible to recommend the determination of plasminogen activity in the management of pregnant women in gynecological practice.

The differential diagnosis of prostate cancer is problematic due to the lack of markers with high diagnostic accuracy. We previously demonstrated the increased binding of IgG to human plasminogen (PLG) in plasma of patients with prostate cancer (PC) compared to healthy controls. Heavy and light chains of PLG (PLG-H and PLG-L) were immobilized on 96-well plates and the binding of IgG to PLG-H and PLG-L was analyzed in serum from 30 prostate cancer (PC) patients, 30 patients with benign prostatic hyperplasia (BPH) and 30 healthy controls using enzyme-linked immunosorbent assay (ELISA). Our results demonstrate that IgG from PC sera bind to PLG-H but not to PLG-L. This interaction occurred through the free IgG C-terminal lysine (Lys) that becomes exposed as a result of IgG conformational changes associated with proteolysis. Circulating levels of modified IgG with exposed C-terminal Lys (IgG-Lys) were significantly higher in PC patients than in healthy controls and in BPH. We used Receiver Operating Characteristic (ROC) analysis to calculate the sensitivity (SN) and specificity (SP) of circulating IgG-Lys for differentiating PC from BPH as 77% and 90%, respectively. The area under the curve (AUC) was 0.87. We demonstrated that the diagnostic accuracy of circulating levels of IgG-Lys is much higher than diagnostic accuracy of total PSA (tPSA).

Introduction. Prostate cancer (PC) leads the world structure of male cancer mortality. Understanding the prognosis for PC patients is vitally important and requires diagnostic enhancements such as developing biomarker panels. The studyaimed to estimate sensitivity, specificity, and prognostic significance of the level of immunoglobulin G (IgG) proteolysis products in the blood serum depending on PC Gleason score and detect how the levels of IgG proteolytic fragments were associated with the diagnostic marker expression. Materials and methods. The study included 90 PC patients. We used the Gleason score to evaluate tumor grade. The level of the IgG proteolysis products and total prostate-specific antigen (PSA) in the serum was detected with ELISA. We performed an immunohistochemical assay with Ki-67, plasminogen-binding protein enolase-1 (ENO-1), and prostate-specific membrane antigen (PSMA). Results. ROC analysis demonstrated 100% specificity of the IgG proteolysis products test regardless of Gleason score, while the sensitivity reached 72.2%, 57.5%, 52.6%, and 46.2% for ISUP stages 1, 2, 3, and 4, respectively. An intergroup comparison showed significant differences between patient groups according to Gleason score, preoperative PSA and IgG proteolysis product serum levels and Ki-67 index. We detected a positive correlation between the level of IgG proteolysis products in the PC patients’ serum and ENO-1 expression and a negative correlation with the Gleason score and PSMA expression. Conclusion. Preoperative detection of high levels of proteolytic IgG fragments in the serum of PC patients even with low Gleason score and PSMA expression may help predict a more aggressive disease course and choose the management strategy. Keywords: prostate cancer, plasminogen activation system, proteolytic fragments of immunoglobulin G, oncomarkers