Fig 3. cSiO₂ exposure increases severity of lupus nephritis in kidneys of NZBWF1 mice.

Representative light photomicrographs of PASH stained kidney sections in NZBWF1 mice at 24 wks of age exposed to vehicle (A) and 1.0mg cSiO₂ (B). NZBWF1 mice exposed to 1.0mg cSiO₂ developed extensive glomerulonephritis (black arrow) and tubular proteinosis (asterisk). NZBWF1 mice were individually graded for lupus nephritis following the modified ISN/RPS classification system as described in the Materials and Methods (C). Animals exposed to cSiO₂ developed more severe lesions characteristic of lupus nephritis than vehicle-exposed mice. cSiO₂ dose significantly correlated with lupus nephritis (Spearman rank-order coefficient = 0.64, p < 0.05).