Isolation of bovine colostral lymphocytes: in vitro blastogenic responsiveness to concanavalin A and bovine rotavirus.

In order to study the in vitro proliferative activity of bovine colostral lymphocytes, the lacteal secretions from four Holstein heifer cows were collected at days 1 and 2 after calving for lymphocyte isolation. A density gradient centrifugation using a Ficoll-diatrizoate solution (sp gr 1.084 g/ml) allowed to isolate a cell population which consisted mainly of lymphocytes. The cell cultures incubated with Con A showed a significant in vitro lymphoblastic transformation, although the mitogenic response was lower than that which was seen with autologous blood lymphocytes. Two of the cows immunized with an adjuvanted-rotavirus vaccine during pregnancy also demonstrated a significant in vitro blastogenic blood and colostrum activity to bovine rotavirus, the higher response being observed with colostral lymphocytes. The immunocompetent cells found in bovine colostrum, with immunological activity to specific antigens, might have a role in passive protection of the neonate.