Automated Aerospray Hematology PRO staining shows good agreement for mature leukocytes but limited diagnostic reliability for immature forms

Introduction: Microscopic examination of peripheral blood smears remains essential step in hematology diagnostics, requiring reliable and standardized staining techniques. This study evaluated performance of Aerospray Hematology PRO Slide Stainer (ELITechGroup Inc., Utah, USA) in comparison with manual May-Grünwald-Giemsa (MGG) technique. Materials and methods: Forty K2EDTA-whole-blood smears were prepared in duplicate and stained using both methods. Hundred samples flagged by Siemens Advia 2120i for atypical lymphocytes (ATYPS), immature granulocytes (IG), blasts and nucleated red blood cells were analyzed for diagnostic accuracy. Precision was assessed using three K2EDTA-whole-blood samples, where 12 smears per sample were evaluated. Manual differential counts of 100 white blood cells (WBC) per slide were performed by experienced laboratory scientist. Data distribution was assessed using Kolmogorov-Smirnov test. Method comparison was performed using Bland-Altman and Passing-Bablok analyses, while sensitivity and specificity were calculated for ATYPS, IG and blasts. Results: Precision results met acceptable criteria for all WBC subpopulations. No significant differences were observed for mature WBCs: intercept - 4.0 (- 13.8 to 3.0) slope 1.0 (0.9 to 1.2) for neutrophils; intercept - 1.5 (- 9.3 to 1.9), slope 1.1 (0.9 to 1.3) for lymphocytes; intercept 1.0 (- 2.0 to 1.6), slope 1.0 (0.9 to 1.4) for monocytes; intercept 0.0 (- 1.5 to 1.3), slope 1.0 (0.5 to 1.7) for eosinophils. Staining of mature WBCs was comparable, showing no significant differences in nuclear or cytoplasmic morphology. While immature WBCs, particularly myelocytes, displayed fewer granules and lighter nuclear staining with Aerospray. Diagnostic accuracy was unsatisfactory for classifying ATYPS (Se = 73%, Sp = 60%), IG (Se = 63%, Sp = 50%) and blasts (Se = 63%, Sp = 100%), whereas erythrocyte and platelet morphology were unaffected. Conclusions: Aerospray Hematology PRO is suitable for mature WBC populations. However, manual MGG staining remains necessary for reliable evaluation of immature and pathological cells.