Monoclonal antibody identification of infiltrating mononuclear leukocytes in lupus nephritis

Monoclonal antibody identification of infiltrating mononuclear leukocytes in lupus nephritis (LN). Populations of mononuclear inflammatory cells infiltrating the renal interstitium in LN were studied by means of an avidin–biotin immunoperoxidase technique applied to cryostat sections of 26 renal biopsies (3 WHO class IIb; 4 class III; 8 class IV; 4 class V; 4 class III and V; and 3 class IV and V). The majority of interstitial leukocytes were T cells (mean 65.7 ± 14.1). The number of cells reactive with OKT8 (47.3 ± 11.0) exceeded the number of OKT4 positive cells (32.5 ± 11.3) in 22 of 26 biopsies. Cells reactive with antimonocyte antibodies OKM1 and OKM5 (6.7 ± 5.9 and 7.9 ± 5.9, respectively) and B lymphocytes (OKB2 3.9 ± 3.5) were a minor component of the interstitial infiltrates. Monocytes were the predominant cell type among stained cells in glomerular tufts and crescents. Tissue T4/T8 ratios varied widely (range 0.31 to 1.81), and were less than 1 in 22 of 26 patients. There was no correlation between tissue T4/T8 ratios and simultaneous peripheral blood T4/T8 ratios. Using stepwise multivariate linear regression, tissue T4/T8 ratio was found to correlate highly with renal histologic activity (P < 0.001) but was not independently predictive of any other histopathologic or clinical variable studied. Mean tissue T4/T8 ratio in LN was significantly lower than that of other glomerular and interstitial diseases studied (P < 0.001), a finding which may reflect differences in the pathogenesis of renal injury. These findings suggest that local cellular immune mechanisms may be important in the modulation of disease activity in LN