S100A6 and Autoimmunity: Furthermore, this was a retrospective study and can have memory bias (in expositional variables referred by participants, as well as blood transfusions); RA-ILD prevalence is low and probably underdiagnosed, and so, the sample size is small; Among strengths, this is the first paper evaluating the anti-HLA antibodies using the PRA test in an autoimmune disorder with interstitial lung disease.