Table 3.

Mitotic HEp-2 IIFA patterns

Code	AC pattern—clinical relevance	Refs
AC-24	CENTROSOME (see online supplementary table 3 for further details)
	The AC-24 pattern has low positive predictive value for any disease
	Within the spectrum of the SARD, the AC-24 pattern is found in patients with Raynaud’s phenomenon, localized scleroderma, SSc, SLE and RA, either alone or in combination with other SSc-associated antibodies;	102–105
	Antigens recognized include α-enolase, γ-enolase, ninein, Cep-250, Mob1, PCM-1/2, pericentrin; specific immunoassays for these autoantibodies are currently not commercially available	104, 106–108
AC-25	SPINDLE FIBERS (see online supplementary table 3 for further details)
	The AC-25 pattern has low positive predictive value for any disease	109
	Found very infrequently in a routine serology diagnostic setting	109
	Antigen recognized includes HsEg5; specific immunoassays for this autoantibody, or other spindle fiber targets, are currently not commercially available	110, 111
AC-26	NuMA-like
	Approximately one-half of the patients with the AC-26 pattern have clinical features of a SARD (SjS, SLE, UCTD, limited SSc, or RA); the AC-26 pattern is also observed in patients with organ-specific autoimmune diseases and less frequently in non-autoimmune conditions, especially when in low titer	109, 111–114
	Found very infrequently in a routine serology diagnostic setting	109
	Antigens recognized include NuMA, centrophilin, SP-H antigen and NMP-22; specific immunoassays for these autoantibodies are currently not commercially available	115
AC-27	INTERCELLULAR BRIDGE (see online supplementary table 3 for further details)
	The AC-27 pattern has low positive predictive value for any disease	116
	Found very infrequently in a routine serology diagnostic setting	117
	Antigens recognized include, among other, CENP-E, CENP-F, TD60, MSA36, KIF-14, MKLP-1, MPP1/KIF20B, and INCENP; specific immunoassays for these autoantibodies are currently not commercially available	116, 118, 119
AC-28	MITOTIC CHROMOSOMAL (see online supplementary table 3 for further details)
	The AC-28 pattern has low positive predictive value for any disease
	Found very infrequently in a routine serology diagnostic setting	120
	Antigens recognized include DCA, MCA1, and MCA5; specific immunoassays for these autoantibodies are currently not commercially available	120–122

CENP, centromere-associated protein; Cep, centrosomal protein; DCA, dividing cell antigen; IIFA, indirect immunofluorescence assay; INCENP, inner centromere protein; KIF, kinesin family; MCA, mitotic chromosomal antigen; MKLP, mitotic kinesin-like protein; MPP, M-phase phosphoprotein; MSA, mitotic spindle apparatus; NMP, nuclear matrix protein; NuMA, nuclear mitotic apparatus; PCM, pericentriolar material; RA, rheumatoid arthritis; SARD, systemic autoimmune rheumatic diseases; SLE, systemic lupus erythematosus; SSc, systemic sclerosis; SjS, Sjögren’s syndrome; UCTD, undifferentiated connective tissue disease.