SP100 and primary biliary cholangitis: Antimitochondrial autoantibodies (AMA), detected by indirect immunofluorescence (IIF) in rodent kidney, liver, and stomach tissues, are the classical specific serological markers for PBC and are found in 90% to 95% of PBC patients.[3] In addition to AMA, PBC-specific ANA, including anti-sp100 and anti-gp210, are present in over 30% of PBC patients found to be negative for AMA.