Low level of circulating basophil counts in biopsy-proven active lupus nephritis

Basophils have been shown to be important players in promoting lupus nephritis (LN). However, the relationship between circulating basophil counts and renal pathology activity of LN remains unclear. In this retrospective study, 159 clinical and pathology samples from patients with biopsy-proven LN were analyzed. The renal activity and classification were evaluated according to renal pathology. The correlations between circulating basophil counts and renal pathology activity index were assessed. Overall, circulating basophil counts correlated with total systemic lupus erythematosus disease activity index (SLEDAI) score (r = - 0.31), renal SLEDAI score (r = - 0.35), activity index (AI) score(r = - 0.40), and renal histologic activity parameters (p < 0.05, respectively). Compared with systemic lupus erythematosus (SLE) non-LN patients, the LN group had lower basophil counts (0.007 ± 0.007 vs. 0.011 ± 0.010 × 10⁹/L, p = 0.04). Subgroup analyses revealed that the circulating basophil counts in group B (AI > 8) were significantly lower than that in group A (AI ≤ 8) (0.004 ± 0.006 vs. 0.009 ± 0.009 × 10⁹/L, p < 0.001). The difference was still significant when eliminating the influence of SLEDAI. Significant differences were found in circulating basophil counts among LN pathology classification groups (p < 0.01). Groups of classes III, IV, and V were more likely to have lower circulating basophil counts when compared with group of class I/II (p < 0.05). These findings suggest a potential role of circulating basophil counts as a convenient and helpful marker for renal activity of LN.