The present study was thus undertaken to detect circulating levels of natural autoantibodies against peptide antigens derived from CD25 and FOXP3 with an enzyme-linked immunosorbent assay (ELISA) developed in-house and to confirm if circulating anti-CD25 and anti-FOXP3 autoantibodies have diagnostic values for early detection of NSCLC. Here, FOXP3 is linked to non-small cell lung carcinoma.