LAUSR

The correspondence of Lee et al 1 questions why the recent paper2 of the international consensus on ANA patterns (ICAP) consortium about the clinical relevance of HEp-2 indirect immunofluorescent assay (IIFA) patterns does not include the HEp-2000 substrate (Immunoconcepts, Sacramento, California, USA). The decision not to include the HEp-2000 substrate origins from the initial conception of ICAP: it was decided not to include manipulated cellular substrates.3 Since the HEp-2000 cells are transfected with the SS-A/Ro60 cDNA, this substrate was not incorporated in the consensus. Obviously, this decision is disputable and perhaps should be reconsidered in the near future. Indeed, it is to be taken into account that also the ‘non-manipulated’ substrates may be different. First, characteristics of the subcultures may have gradually deviated from the original HEp-2 cells. It is even argued that in time the HEp-2 cells have been contaminated with HeLa-cells.4 Second, diagnostic companies use distinct fixation procedures that eventually also may affect the HEp-2 IIFA patterns. Cell cycle progression can also be manipulated in order …