Role of β2 integrins in glomerular leucocytes in Henoch‐Schoenlein purpura nephritis: an age‐matched comparative study with immunoglobulin A nephropathy

Abstract

SUMMARY: A comparative immunohistological study was performed for the glomerular deposition of complements (C1q and C3c), fibrin/fibrinogen‐related antigen (FRA), the expression of intercellular adhesion molecule‐1 (ICAM‐1), and the infiltration of leucocytes bearing β2 integrins (leucocyte function associated antigen‐1 (LFA‐1), complement receptor 3 (CR3) and complement receptor 4 (CR4)) on renal biopsy specimens from 49 cases with Henoch‐Schoenlein purpura nephritis (HSPN), and 49 age‐matched cases with immunoglobulin A nephropathy (IgAN). the glomerular expression of ICAM‐1 was signifcantly correlated with the glomerular infiltration of leucocyte function associated antigen (LFA)‐1+ leucocytes in both diseases, and with that of CR3+ leucocytes in HSPN. the expression of ICAM‐1 was closely localized with the infiltration of LFA‐1+ leucocytes in the study with double immunostaining. the incidence and intensity of glomerular deposition of FRA were significantly higher in HSPN than in IgAN (P< 0.001), and those of C3c were significantly lower in HSPN than in IgAN (P< 0.001). the glomerular deposition of FRA was significantly correlated with the glomerular infiltration of CR4+ leucocytes in HSPN (P<0.05) but not in IgAN. In contrast, the glomerular deposition of C3c was significantly correlated with the glomerular infiltration of CR4+ leucocytes in IgAN (P<0.05), but not in HSPN. Studies with double immunostaining revealed a close association of CR4+ leucocytes with FRA deposition in HSPN and with C3c deposition in IgAN, respectively. the number of glomerular leucocytes bearing β2 integrins was significantly correlated with urinary protein at the time of renal biopsy in both diseases. These results suggested the differential roles of β2 integrins in the induction of glomerular injury in HSPN and IgAN. the ICAM‐1/LFA‐1 interaction may commonly be involved in the glomerular infiltration of leucocytes in both diseases. the ICAM‐1/CR3 interaction may be involved only in HSPN. Complement receptor 4 may function as a fibrin/fibrinogen receptor in HSPN, while CR4 may function as a complement receptor in IgAN.