Abstract
The discoverer of transmissible leucosis, Ellermann, thought that there is no immunity to leucosis because fowls resisting one inoculation may succumb to reinoculation. More recent knowledge gained on immunity against Rous tumors (Rous, Mottram, Andrewes, Mueller, etc.) necessitates a revision of this conclusion.
Active immunity. Cell-free virus and leucemic cells must be considered separately, because leucemic cells behave like neoplastic cells and specific immunity is not known to develop in tumor-bearing animals. Furthermore the virus itself may be protected from immune bodies by association with cells. Accordingly 8 possibilities were tested with the following results :
The fowls resistant both to cell-free virus and leucemic cells are those that were previously injected with material containing live leucemic cells. Their resistance may in part be due to antibodies against the free virus; antibodies active against leucemic cells have however thus far not been demonstrated. Resistance to reinjection with cells if not caused by acquired immunity, may be either an inherited character becoming manifest through elimination of susceptible fowls by the first injection, or a non-specific resistance-increase due to the first injection, or to other conditions, such as advancing age.
The reinjections were made with 0.5 to 1 cc. of leucemic blood or plasma, estimated to contain 10,000 to 1,000,000 infective doses. It is possible that smaller amounts may reveal some immunity in groups 1, 3, 4. Among the 56 fowls tested, 4 had lymphoid leucosis (as compared to 14 with transmissible leucosis). They were grouped as negative, because according to previous investigations lymphoid leucosis is not caused by the agent of transmissible leucosis.
Passive immunity. When leucemic plasma of fowls was mixed with the serum of presumably immune fowls and injected within about 20 minutes, a mild but distinct protection was observed.
Get full access to this article
View all access options for this article.