Abstract
Summary
The spontaneous regression of avian myeloblastosis virus (AMV) induced leukemia was observed in two chicken lines. When the virus was injected intravenously into 17 day old Kimber embryos, 15% of the resultant leukemias spontaneously regressed. If a relatively resistant chicken line (C/AB) was used, 62% of the leukemias spontaneously regressed. Nearly one-third of the regressed chickens experienced a fatal relapse. Over 30% of the bone marrow in both regressed Kimber and C/AB chickens consisted of abnormal blast-like cells. Nearly 40% of the regressed birds evidenced lymphoma-like tumors upon autopsy. Kimber chickens were viremic during both the acute phase and during regression, while infectious AMV could not be recovered from the C/AB at any time. Buffy coat cultures from regressed Kimber and C/AB always resulted in the reappearance and proliferation of myeloblasts. Splenic lymphocytes from regressed Kimber chickens were found to inhibit colony formation of leukemic myeloblasts in semisolid medium.
We gratefully acknowledge the help of Dr. Armand Glassman for interpreting the numerous histological sections. We thank J. Hilliard and J. Wetherell for technical assistance.
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