Anti-sp100 antibodies explained

Anti-sp100 antibodies are found in association with primary biliary cirrhosis.^[1] The autoimmune target of anti-sp100 is the sp100 nuclear antigen which was identified by its association with primary biliary cirrhosis. 20-30% of patients with primary biliary cirrhosis have sp100 Abs. The sera of these patients exhibit a characteristic "nuclear dots" pattern in indirect immunofluorescence (IIF) on Hep-2 cells.

Immunodominant regions of sp100

• Antigenic region 1 - positions 296-311 - Sequence (I K K E K P F S N S K V E C Q A)
• Antigenic region 2 - positions 332-351 - Sequence (E G S T D V D E P L E V F I S A P R S E)

(Bolded areas represent the core epitope.)^[2]

Notes and References

1. Szostecki C, Guldner HH, Netter HJ, Will H . Isolation and characterization of cDNA encoding a human nuclear antigen predominantly recognized by autoantibodies from patients with primary biliary cirrhosis . J. Immunol. . 145 . 12 . 4338–47 . 1990 . 2258622 .
2. Blüthner M, Schäfer C, Schneider C, Bautz FA . Identification of major linear epitopes on the sp100 nuclear PBC autoantigen by the gene-fragment phage-display technology . Autoimmunity . 29 . 1 . 33–42 . 1999 . 10052683 . 10.3109/08916939908995970 .