Conditions affecting clonal growth of lymphoma cells in a semisolid matrix.

This study demonstrated the importance of the methods used in determining the lymphoma cell colony stimulating activity of factors derived from lymphoma cells. The in vitro colony formation in a semisolid matrix of the AKR mouse lymphoma cell line, SL 12, and three cloned derivatives, SL 12.1, SL 12.3, and SL 12.4, was studied. We show that the use of soft agar or methylcellulose as a semisolid matrix results in colony formation by the lymphoma cells only in the presence of serum. The addition of conditioned medium (CM) from lymphoma cells growing in serum-free medium does not stimulate colony growth. However, when purified agarose is used, colonies grow in a dose-dependent manner in the absence of serum and in the presence of CM. These results indicate that the type of semisolid matrix used can influence results in studies of this nature. Purified agarose provides the best environment when colony formation by lymphoma cells is used to measure the presence of growth factors in test-conditioned media.