OBJECTIVEMast cells and eosinophil have been found to play important roles not only in the development of anaphylactic inflammation but also in the chronic progression of organ reconstruction. But their role in the pathogenesis of Henoch-Schonlein purpura nephritis (HSPN) has not been fully understood. The present study was conducted to observe the serum levels of eosinophil cationic protein (ECP) and renal infiltration of mast cells in HSPN in order to elucidate their role in the development and progression of HSPN in children.

METHODSThe serum ECP levels were determined in 46 children with HSPN by fluoro-enzyme immunoassay (FEIA) using the Pharmacia CAP System. The distribution of mast cells infiltration was detected by immuno-enzyme-histological staining of tryptase (a marker for mast cell activation) and their relation with pathological changes was analyzed in 32 children with HSPN.

RESULTSThe serum ECP levels were 16.3 +/- 6.5 microg/L in the active stage of HSPN, significantly higher than that in remission stage (3.9 +/- 1.4 microg/L, P < 0.01) and that in control group (3.1 +/- 1.7 microg/L, P < 0.01). The number of mast cells in renal interstitium was 4.4 +/- 2.4 cells/mm2 in normal kidney, and significantly increased to 27.2 +/- 19.2 cells/mm2 in children with HSPN ISKDC grade II (P < 0.01) and 42.1 +/- 16.4 cells/mm2 in grade III (P < 0.05 when compared with grade II), 77.9 +/- 15.0 cells/mm2 in grade IV (P < 0.05 when compared with grade III).

CONCLUSIONThe serum ECP level could reflect disease activity of HSPN, and mast cell infiltration in kidney correlated significantly with renal histological severity in HSPN. Mast cells and eosinophil may play important roles in the development and progression of HSPN.