<strong>Immunofluorescent Staining:</strong> Chicken peripheral blood mononuclear cells were double-stained with Mouse anti-Chicken IgM-FITC and Mouse anti-Chicken CD3-PE. Small lymphocytes were then gated and analyzed on a FACScan(TM) flow cytometer (BDIS, San Jose, CA). Amount Used: 1 ug/10e6 cells.