Aims: To determine the possible relationship between macrophage phenotypes and the progression of kidney disease in patients with lupus nephritis (LN).

Methods: Using immunohistochemistry, CD68+ and CD163+ cells were counted per glomerulus and per high-power field in the tubulointerstitium. Progression was defined as a doubling of the serum creatinine level and/or progression to end-stage kidney disease.

Results: Among the 21 patients, 52% had class III or IV LN. During the median follow-up of 88 months, 5 (23.8%) patients experienced progression. In terms of clinical and pathological markers, the only significant difference between progressors and nonprogressors was the number of interstitial CD163+ cells (median 4 versus 2.4, respectively; p=0.025). A cutoff value of 2.7 for the mean number of CD163+ cells in the interstitium yielded a sensitivity of 80% and specificity of 75% for progression. The estimated median time to progression among patients with ≥2.7 CD163+ cells was shorter (median 136 versus 202 months, p=0.023). A greater number of CD163+ cells in the kidney interstitium was associated with the progression of kidney disease (HR 2.88, 95% CI 1.22-6.80; p=0.016). Class III-IV LN was associated with a higher median number of glomerular CD163+ cells (OR 1.96, 95% CI 1.1-3.49, p=0.023). Endocapillary hypercellularity and extracapillary proliferation were associated with greater number of CD163+ cells in the glomerular area. Among patients with class III-IV LN, the number of interstitial CD68+ cells was greater in those who experienced progression of kidney disease (p=0.012).

Conclusion: A greater number of CD163+ cells in the kidney interstitium was associated with the progression of kidney disease in patients with LN, while a greater number of CD68+ cells in the interstitium was associated with progression in the subgroup of patients with class III-IV LN.