Optimal conditions for in vitro blastogenesis of feline peripheral blood lymphocytes.

A microculture technique was developed for the in vitro blastogenesis of feline lymphocytes. Blastogenesis of ficoll-diatriazoate gradient separated mononuclear cell, washed blood and whole blood were compared. In general the whole blood cultures yielded higher stimulation indices (SI) than the washed blood or separated mononuclear cell cultures. The effect of several variables on the stimulation of lymphocyte cultures was examined. A cell concentration of 3 x 10(5) cells/well and a 1:20 dilution of washed and unwashed whole blood gave optimal stimulation with concanavalin A (Con A). Phytohaemagglutinin-P (PHA-P) did not give significant levels of stimulation. Inactivated fetal calf serum (FCS) at levels of 2.5% (for washed blood) and 5% (for separated mononuclear cell and whole blood) gave highest SI. Supplementation with FCS was preferable to autologous, homologous or horse sera for all cultures. Optimal SI was obtained in all cultures incubated for 3 days and labelled with 1 microCi tritiated thymidine (3H-TdR) for the last 16 hours. The highest SI were in the range of 70 to 105 (18,764 to 42,681 counts per minute (CPM) for separated mononuclear cell culture, 100 to 165 (28,403 to 45,334 CPM) for washed blood culture and 105 to 186 (41,076 to 69,999 CPM) for whole blood culture.