Methods:

Thirty-two renal biopsies of active lupus nephritis patients were studied. Clinical assessment by the systemic lupus activity measure (SLAM-R) score and laboratory data were included [serum creatinine, 24-h urinary protein, antinuclear antibodies (ANA), anti-double-strand DNA antibodies (anti-dsDNA), C3 and C4]. Light (L/M) and electron microscopic (E/M) examination was conducted. Podocyte loss was evaluated by immunohistochemistry with monoclonal anti-podocalyxin antibodies by means of a semiquantitative score that was graded from 0 to 4+ according to the percentage of glomerular involvement.

Results:

22 cases (68.8%) with LN class IV, 6 (18.8%) with class III and 4 (12.5%) with class V. The mean age was (25.41 ± 10.13) years. There was a significant negative correlation between IHC podocalyxin score and LN class, and NIH activity parameters such as leukocyte infiltration, endocapillary proliferation, fibrinoid necrosis and cellular crescent and disease activity index but not chronicity index. There was a highly significant negative correlation between IHC podocalyxin and podocyte effacement by E/M (rs = −0.903, P = 0.000), and E/M immune deposits (r = −0.53, P = 0.001), and a significant association with degree of proteinuria, ANA and SLAM score (P < 0.05).

Conclusions:

Podocyte loss indicated by podocalyxin immunohistochemical expression reflects the degree of activity and severity of LN and the degree of podocyte effacement by E/M.

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