Use of poly-l-lysine-coated slides in clinical bronchoalveolar lavage fluid samples

Polylysine coating of microscope slides provides superior cell adhesion. We compared poly-l-lysine-coated (PLC) slides to conventional slides in cytocentrifuged bronchoalveolar lavage (BAL) fluid samples.

Twenty BAL fluid samples with representative numbers of alveolar macrophages, lymphocytes and polymorphonuclear neutrophils were cytocentrifuged on uncoated slides and on PLC slides (2 slides each). Cell density, differential cell counts and cytomorphology were assessed on May-Grünwald-Giemsa-stained preparations. Reliability of cell differentiation was expressed as a phi value, which measures combined reproducibility and agreement. Statistical significance of differences between slides was calculated with ANOVA. Clinical relevance was assessed using a validated computer program predicting the most probable diagnosis.

Although not statistically significant, cell recovery was lower on PLC slides as compared to uncoated slides. PLC slides held significantly fewer lymphocytes as compared to uncoated slides (mean value +/- SD: 25.89% +/- 28.26 versus 28.34% +/- 29.96, respectively). Counts of alveolar macrophages, lymphocytes and polymorphonuclear neutrophils displayed excellent phi values for both uncoated and PLC slides. No discrepancies in the computer-generated diagnoses were found.

For BAL fluid cytology on cytocentrifuged preparations, PLC slides are not superior to conventional slides.