Transfer of natural resistance to Marek's disease (JMV) with non‐immune spleen cells. I. Studies of cell population transferring resistance

A “natural” resistance to Marek's disease, as well as to the malignancy caused by the laboratory JMV line of Marek's disease, develops with age. Resistance to this malignancy can be transferred from non‐immunized, 8‐week‐old resistant chickens to newly hatched susceptible ones with spleen cells in a B‐locus isogeneic combination. The cell transferring resistance does not seem to belong to the major T‐cell, B‐cell, or macrophage populations, and seems consequently to belong to the functionally heterogenous “third cell” population.