Antigen profiles for the quantitative assessment of eosinophils in mouse tissues by flow cytometry

Much of our current understanding of eosinophil-associated pathologies has developed from the use of mouse models. While mouse eosinophils can be readily detected by flow cytometric methods, most studies do not document the efficiency of this process compared to direct counting of stained cells. Our intent was to address this knowledge gap by identifying one or more eosinophil-specific antigen profiles that yielded flow cytometric data that was statistically consistent with direct counts. We found that anti-CD193 (CCR3) and anti-CD125 (IL-5Rα) antibodies were effective at detecting eosinophils in bone marrow of interleukin-5 transgenic mice, but these antibodies under-reported the percent positive cells. In contrast, anti-Siglec F alone or in combination with anti-CD45 can be used for the quantitative detection of eosinophils in mouse bone marrow and spleen. The antigen profile CD45(+)SiglecF(+)CD11c(-) was effective at detecting eosinophils in the lung as well as bone marrow and spleen, and the results obtained correlated with direct morphometric counts under all conditions evaluated (r(2)=0.98-0.99). To the best of our knowledge, this is the first systematic analysis presenting definitive correlations between percent eosinophils detected by cell surface markers and direct counting of stained cells in multiple tissues and at varying degrees of eosinophilia.