ABSTRACT
The parameters involved in the choice of an optimal T cell growth activity (TCGAc) induction protocol using rat spleen cells simultated with jacalin were studied. In the absence of serum, 5 microng/ml jacalin was sufficient to obtain maximal TCGAc, Supernatants could be harvested at any time between 24 and 72 h since significant consumption of TCGAc was not observed during this interval. TCGAc recovery was increased in the presence of 5% fetal calf serum, with the optimal jacalin dose being about 25 microng/ml. The recommended harvesting time was 24 h to reduce TCGAc loss due to cellular proliferation. Human or rat sera were not suitable since they absorb significant amounts of jacalin, thus shifting the optimal lectin concentration to > 800 microng/ml. Indomethacin (1 microng/ml) had little enchancing effect on TCGAc production by rat cells but rendered conditioned media less inhibitory of cytotoxic T lymphocyte L (CTLL) proliferation. Addition of 50 ng/ml phorbol myristate acetate is not recommended if the supernatants are to be used for T cell line maintenance, since the agent interferes with CTL function, while only doubling TCGAc production. Jacalin-stimulated TCGAc recovery is comparable, in titer, to that obtained with concanavalin A under the best conditions, but the former is less expensive due to the large quantities of lectin recovered from a single jackfruit, besides being less toxic for rat spleen cells