Studies on the Transfer of Protective Immunity with Lymphoid Cells from Mice Immune to Malaria Sporozoites¹

In an effort to understand the mechanisms involved in the protective immunity to malarial sporozoites, an A/J mouse/Plasmodium berghei model was studied. Protective immunity could consistently be adoptively transferred only by using sublethal irradiation of recipients (500 R); a spleen equivalent (100 × 10⁶) of donor cells from immune syngeneic mice; and a small booster immunization (1 × 10⁴) of recipients with irradiation-attenuated sporozoites. Recipient animals treated in this manner were protected from lethal challenge with 1 × 10⁴ nonattenuated sporozoites. Immune and nonimmune serum and spleen cells from nonimmune animals did not protect recipient mice. Fewer immune spleen cells (50 × 10⁶) protected some recipients. In vitro treatment of immune spleen cells with anti-ϑ sera and complement abolished their ability to transfer protection. This preliminary study suggests that protective sporozoite immunity can be transferred with cells, and that it is T cell dependent.