Bacterial antigen and acid phosphatase in macrophages in experimental pyelonephritis.

Experimental retrograde E. coli pyelonephritis was produced in rats. The study covered the period from 6-24 hours up to 6 months. Macrophages in the renal tissue were studied using immunofluorescence staining for bacterial E. coli antigen and histochemical staining for aicd phosphatase. A comparison of sections stained according to the two methods showed that antigen-containing macrophages in nearly all cases yielded a positive reaction for acid phosphatase. On the other hand, in several kidneys acid phosphatase-positive macrophages occurred which in consecutive sections studied by immunofluorescence did not contain antigen. The possibility of using staining for acid phosphatase as a screening method for the detection of active, antigen-containing macrophages in human chronic pyelonephritis is discussed.