Immuno-histochemical Assessment of Anti-CD45 Staining: A Predictor of Disease Activity and Short-Term Outcome in Lupus Nephritis

Background Lupus nephritis (LN) remains a major cause of morbidity in systemic lupus erythematosus (SLE). Conventional glomerulocentric classifications often underrepresent tubulointerstitial (TI) inflammation, which may hold independent prognostic value. This study aimed to evaluate whether anti-CD45 immunostaining can serve as a quantifiable marker of TI inflammation and to examine its association with short-term clinical outcomes by assessing CD45 expression in LN. Materials and Methods This observational study enrolled 43 adults with biopsy-proven LN at Bangabandhu Sheikh Mujib Medical University, Dhaka (Sept 2021–Aug 2022), meeting revised ACR criteria. Exclusion criteria included coexisting infections, malignancy, or inadequate biopsy. Renal biopsies were evaluated per ISN/RPS 2003 classification, with anti-CD45 immunostaining used to assess leukocyte infiltration. Patients were followed-up for 6 months. Results Mean age of the study population was 28.4 ± 7.7 years, with 86.0% female respondents. Class IV was most prevalent (41.9%), with moderate-to-severe activity in 71.4% and mild chronicity in 71.4%. Anti-CD45 deposition was more frequent in the interstitium (58.1%) than in glomeruli (41.9%), with moderate intensity in 53.5%. Higher anti-CD45 deposition intensity correlated with increased TI involvement, chronicity index, and SLEDAI scores ( p <0.05). Linear regression showed a significant positive association between anti-CD45 deposition intensity and baseline SLEDAI (R 2 = 0.253, p = 0.0077). Treatment response at 6 months was inversely related to anti-CD45 deposition intensity: complete remission occurred in 100% of patients with no deposition, but only 11.1% with severe deposition. Conclusion Anti-CD45 deposition, particularly in the TI compartment, reflects heightened immune activity and aligns with poorer treatment outcomes in LN. These findings highlight its potential as a biomarker that could enhance current histological assessment. Further validation in larger and multi-center studies is required.