Comparative immunochemical study of lectin-binding sites and cytoskeletal filaments in static and reactive mesothelium and adenocarcinoma

In cytological preparations, reactive mesothelial cells (RMC) in serous effusions are sometimes difficult to distinguish from adenocarcinoma cells (AC). RMC and AC can be distinguished by lectin-binding patterns, but the pattern of binding of lectins to normal mesothelium is not well defined. We investigated the expression of cytoskeletal filaments, cytokeratin (CK) and vimentin (VM), and the cell surface binding pattern of 10 lectins (HPA, SBA, ABA, DSA, PNA, RCA-I, UEA-I, LTA, WGA and ConA) in the serosa of 48 adenocarcinoma specimens. We also investigated the usefulness of six lectins (HPA, SBA, RCA-I, UEA-I, LTA and WGA) in identification of RMC and AC in 16 serous effusions. DSA reactivity was significantly higher (P < 0.05) in static mesothelial cells (SMC) than in RMC. Reactivity for LTA and ConA was significantly lower (P < 0.05) in SMC than in RMC. Anti-CK and anti-VM immunoreactivity was always positive in RMC and almost negative in SMC. In serous effusions, HPA, SBA and UEA-I binding was evident in 100, 88 and 81% of AC, respectively. Little to no binding of HPA, SBA or UEA-I was detected in RMC. Our results suggest that the morphological differences between SMC and RMC are likely to be due to differences in cytoskeletal composition, with accompanying changes in cell-surface lectin-binding patterns. HPA, SBA and UEA-I are likely to be useful markers for identification of RMC and AC in cytology.