PCNA, Proliferating Cell Nuclear Antigen is a protein that is only expressed in normal cancer and proliferating cells. This is a nuclear antigen with a role in DNA synthesis, DNA repair, and cell cycle progression. PCNA is required for the coordinated synthesis of both leading and lagging strands at the replication fork during DNA replication. PCNA expression correlates with the proliferation activity of several malignant and nonmalignant cell types. These antibody PCNA cells are observed in patients with systemic lupus erythematosus (SLE). This Anti PCNA test is done on a test quantity of blood collected from the patient to quantify the levels of Anti PCNA in the blood and to confirm SLE and as well during and after the treatment of systemic lupus erythematosus.