Table 4. Autoantigens and related clinical phenotypes according to IIF patterns

IIF patterns (Hep-2)	Autoantigens	Related clinical phenotypes
Nuclear
Homogenous	Nucleosome (i.e., dsDNA, histones)	SLE, drug-induced LE
Specked, fine	Ro/SSA, La/SSB, Scl-70 (topoisomerase 1)	SjS, SLE, SSc (diffuse), SSc/PM overlap
Specked, coarse	Spliceosome (i.e., Sm, U1-RNP)	SLE, MCTD
Centromere	Centromere protein (CENP-A/B/C)	SSc (limited), primary biliary cirrhosis
Nucleolar	RNA polymerase, PM/Scl, U3-RNP (fibrillarin)	SSc (diffuse), SSc/PM overlap
Cytoplasmic	Ribosomal P, Jo-1, mitochondrial protein	SLE, IIM, interstitial lung disease

IIF: indirect immunofluorescence; dsDNA: double-stranded deoxynucleic acid; SSA: Sjögren’s syndrome-related protein A; SSB: Sjögren’s syndrome-related protein B; RNP(s): ribonucleoprotein(s); CENP: centromere protein; RNA: ribonucleic acid; SLE: systemic lupus erythematosus; SSc: systemic sclerosis; SjS: Sjögren’s syndrome; SSc/PM: systemic sclerosis/polymyositis; MCTD: mixed connective tissue disease; IIM: idiopathic inflammatory myopathy.