Transfer of natural resistance to Marek's disease (JMV) with nonimmune spleen cells. II. Further characterization of protecting cell population.

Spleen cells from 8-week-old, nonimmunized donor chickens can transfer resistance to a supralethal dose of the JMV leukemia line of Marek's disease (MD) to newly hatched, highly susceptible, histocompatible recipients. The population of cells transferring resistance has previously been shown to be non-T, non-B, and nonmacrophage in nature. We present data here showing that heavily x-irradiated spleen cells were unable to protect recipients from leukemia challenge. Both complement receptor-bearing and -lacking cells could confer resistance to newly hatched recipients. Fc receptor-bearing cells conferred significant protection to recipients, whereas spleen cells depleted of Fc receptor-bearing cells were unable to protect chickens from death after JMV challenge. This indicates that the population of spleen cells, which is moderately radiosensitive and which possesses Fc receptors, is responsible for the transfer of natural resistance to the malignancy in vivo.