FIGURE 1

(A) The glomerulus shows a segmental area of tuft necrosis associated with a small cellular crescent. A periglomerular leukocyte infiltration is also present (Trichrome; 250). (B) Immunofluorescence. Deposits of IgA located mainly in the mesangial stalk region (anti-IgA antiserum; 250). (C) Immunofluorescence. Fibrinogen is strongly positive only in well-delineated areas of the glomerular tuft, corresponding to areas of segmental intracapillary necrosis seen at light microscopy (antifibrinogen antiserum; 250). (D) The glomerulus shows monocyte infiltration restricted to a segmental area of the tuft (immunoperoxidase conjugated anti-CD68 antibody; 250). (E) Intense periglomerular leukocyte infiltration in a patient with necrotizing lesions is evident (immunoperoxidase-conjugated anti-CD45 antibody; 250). (F) Strong positivity of adhesion molecule VCAM-1 is present in segmental area of the glomerular tuft corresponding to necrotizing crescentic lesion seen by light microscopy (immunoperoxidase conjugated anti–VCAM-1 antibody; 250). (G) The adhesion molecule ICAM-1 is significantly overexpressed and extended to the whole mesangial area in a glomerulus from a patient with IgAN. (H) In a repeat biopsy, a well-delineated segmental area of glomerular sclerosis with Bowman's capsule adhesion is present, as a consequence of previous (first biopsy) localized necrotizing-extracapillary lesion (Trichrome; 250).