Phytomitogen- and antigen-induced blast transformation of feline lymphocytes.

A semiautomated microassay of blast transformation of feline lymphocytes was developed and used in a study of the response of normal cats to phytomitogen- and antigen-induced stimulation. Peripheral blood lymphocytes were isolated from defibrinated blood by ficolldiatrizoate gradient centrifugation and incubated at a concentration of 1 X 10(5) cells/culture. Blast transformation was measured by the incorporation of tritiated thymidine, to which the cells were exposed during the last 18 hours of incubation. Phytomitogens induced maximal transformation after 3 days' incubation. Greatest stimulation produced by 10 mug of concanavalin A (38- to 183-fold) followed by 4 mug of pokeweek mitogen (nine- to 51-fold), and finally phytohemagglutinin-P (three- to sixfold). Three of 4 cats sensitized to keyhole limpet hemocyanin responded when exposed to 50 mug of keyhole limpet hemocyanin in vitro, maximal transformation occurring after 4 days' incubation. Lymphocyte blast tranformation provides a convenient technique to assess lymphocyte function serially during experimentally induced immunologic alterations in the cat.