The positive ratio of anti-PTX3 auto-antibodies in SLE without the renal involvement group was significantly higher than that in the lupus nephritis group (40.7% (61/150) versus 19.4% (38/196), p < .001) and healthy controls (40.7% (61/150) versus 2% (2/100), p < .001). This evidence concerns the gene PTX3 and systemic lupus erythematosus.