The bovine lymphoid system: binding and stimulation of peripheral blood lymphocytes by lectins.

We tested ability of 11 different lectins to stimulate DNA synthesis in bovine peripheral blood lymphocytes, using a wide range of experimental conditions. Five of the 6 lectins which induced DNA synthesis (concanavalin A, succinyl-concanavalin A, phytohemagglutinin M, pokeweed mitogens and lipopolysaccharide) did so under conditions similar to those optimal for stimulation of murine lymphocytes. The other lectin (peanut agglutinin) stimulated normal bovine lymphocytes whereas it does not stimulate normal mouse, rat, guinea pig or human lymphocytes. The binding of 5 different lectins to bovine peripheral blood lymphocytes was measured by fluorescence microscopy. Four of the lectins bound to various proportions of cells. Double labeling experiments using a rhodamine-labeled goat anti-bovine immunoglobulin reagent and fluorescein-labeled lectins showed that both peanut agglutinin and soybean agglutinin bound to lymphocyte populations which were negative for surface immunoglobulin. The majority of lymphocytes negative for surface immunoglobulin bound peanut agglutinin, indicating that this lectin may bind specifically to bovine 'T' lymphocytes.