The influence of laparoscopic and open surgery on the concentration and structural modifications of insulin-like growth factor binding protein 3 in the human circulation

Insulin-like growth factor binding protein 3 (IGFBP-3) is the most abundant insulin-like growth factor binding protein in the circulation. The aim of the present work was to investigate the influence of surgery (laparoscopy and open) on the concentration and carbohydrate content of IGFBP-3. The concentration of IGFBP-3 was measured using an immunoradiometric assay (IRMA), its protein profile was characterised using immunoblotting and its sialic acid content was examined by means of Sambucus nigra agglutinin (SNA) affinity chromatography. The concentration of IGFBP-3 was significantly (p < 0.001) lower in preoperative patients compared with healthy subjects. Only patients that underwent open surgery showed a further significant decrease in the concentration of IGFBP-3. Immunoblotting detected two intact IGFBP-3 isoforms, as well as proteolytic fragments. SNA-affinity chromatography showed that in patients that underwent surgery the ratio between the two IGFBP-3 glycoforms was lower than the ratio in healthy subjects. Patients with gallbladder inflammation that underwent laparoscopy had an increased percentage of specifically bound IGFBP-3 to SNA compared with healthy subjects. Our conclusion is that open surgery decreased the level of IGFBP-3 compared with laparoscopy, whereas patients with gallbladder inflammation that underwent laparoscopy had an increased content of sialic acid in IGFBP-3.