Apoptosis in canine lymphomas and leukemias: preliminary results

Background: Alteration of apoptosis contributes to carcinogenesis, tumor progression, and treatment resistance. Apoptotic activity might be determined as percentage of apoptotic cells (PAC) by flow cytometry. Objective: Compare apoptosis in different canine lymphomas (LSA) and leukemias. Methods: PAC was detected in 48 LSAs (lymph node aspirates), 15 leukemias, and 9 LSA/leukemias (EDTA blood) by flow cytometry using AnnexinV- FITC/PI staining. Samples were both fresh and shipped by courier. Results: Higher PAC was detected in B- respect to TLSAs and in shipped relative to fresh samples. Shipped B-LSAs showed higher PAC than fresh B-LSAs; no differences were detected among T-LSAs. No differences between fresh and shipped blood samples were recorded. B and T lymphoid leukemias presented similar values. Too few cases were available to explore differences among and between ALL and CLL and to confirm statistically the following descriptive results. Decreasing PACs were recorded in AML vs. AUL vs. ALL and CLL. LSA/leukemias showed higher PAC than leukemias. The only LSA/ALL case showed a clearly higher value than ALLs. LSA/CLLs reported higher medium PAC than CLLs but similar median values. Conclusions: B-LSAs show higher apoptotic activity than T-LSAs but only in shipped samples. 24 h-storage seems to influence PAC in lymph nodes but not in blood samples. Detection of apoptosis could help in characterizing different leukemias. Comparison with blood from stage-V LSAs will help to evaluate usefulness in differentiating blood pictures. A larger series will allow to define the effect of B/T lineage respect to time on apoptosis and to explore its role in identifying subgroups with potential prognostic significance among the main types of LSAs and leukemias.