Flow cytometric evaluation of monoclonal antibodies for cross-reactivity with feline leukocytes

Monoclonal antibodies are essential tools for immunophenotyping, yet their use in feline flow cytometry is highly restricted due to the scarcity of cat-specific antibodies. Moreover, data on cross-reactivity with feline peripheral blood are limited. In this study, peripheral blood from four healthy cats was analysed using flow cytometry to assess cross-reactivity of 72 monoclonal antibodies, including 55 CD markers, 4 chemokine receptors, 7 cytokines, and 6 miscellaneous markers. Cross-reactivity was observed for 35 antibodies. Temporal effects on signal detection were evaluated using a long-term stability assessment of a staining panel comprising CD4, CD5, CD8, CD21, CD56, CD80, and Ki67. Signal detection was optimal immediately after staining and declined over time, and inter-individual variability among the cats was noted. These findings provide a validated set of cross-reactive antibodies and highlight temporal effects on signal detection in peripheral feline blood, supporting reliable flow cytometric analyses.