MATERIALS AND METHODS

Animals. Mice were either purchased from The Jackson Laboratory (Bar Harbor, Maine) or were raised in our own animal colonies. Goats were purchased through and housed at the National Institutes of Health Animal Center (Poolesville, Md.).

Tumors. The BALB/c lymphoid lines K46, BALENLM 17, A20, and X16 were maintained by continuous passage in modified Eagle-Hanks’ medium (EHAA)‘supplemented with 10% heat-inactivated fetal calf serum (FCS), 0.135% sodium bicarbonate (NaHC03), 2 mM glutamine, 5 X M Z-mercaptoethanol, and streptomycin 50 pg and penicillin G 50 units/ml, as previously described (16). The cultures were carried in plastic Petri dishes at 37’C in a moist atmosphere containing 5% C02. Cultures were split every 3 to 4 days by mixing and replacing two thirds of the medium in each dish. The fluid removed was then centrifuged, and the supernatant was harvested and pooled for further characterizations.