Immunoglobulin G isolation by fast protein liquid chromatography (FPLC): Method validation and implementation in patients with amyotrophic lateral sclerosis – a preliminary study

Amyotrophic lateral sclerosis (ALS) is a fatal, heterogenous neurodegenerative disease which is characterized by weakness and muscle atrophy. While more than 50 genes linked with the familial ALS have been identified, sporadic ALS accounts for the majority of cases and genetic factors contributing to the sporadic form of the disease remain largely elusive. Involvement of the immune system in disease progression, including presence of circulating autoimmune complexes, associations with other autoimmune diseases, as well as immunoglobulin (Igs) levels have been described. However, investigations involving immunoglobulins requires isolation of patient antibodies, while so far, there is no validated fast protein liquid chromatography (FPLC) protocol. For this purpose, we evaluated specificity, accuracy and precision parameters; limit of detection, limit of quantification and correlation coefficient were calculated from the calibration curve. Our results indicated the limit of detection and limit of quantification as 0.045 and 0.13 mg respectively, while r2 was calculated as 0.9992. Our preliminary data suggest that this protocol can be implemented for the isolation of IgGs of ALS patients’ sera samples for in vitro and in vivo analyses, while more studies involving larger patient groups are required.