PTX3 and lupus nephritis: Next, the immunohistochemistry results showed that PTX3 were mainly found in tubulointerstitial areas of lupus nephritis patients but negative in glomeruli, in comparison with it stained positive in the mesangium of IgA nephropathy patients which was consistent with Bussolati report.27 The mean optical density of PTX3 in tubulointerstitium correlated closely with the extent of renal activity indices such as interstitial inflammation and interstitial fibrosis in lupus nephritis.