Quantitative studies on intracytoplasmic A particles formed in DBA-2 mouse leukemias.

lymph nodes from the same mice were at almost identical levels. This provided a basis for estimating A-particle formation of the whole body from the API of a single node. The following observations were made: (a) in 322 cases of spontaneous leukemias, API levels varied greatly from case to case, ranging from 0 to 80; (b) males and the aged contained more A particles than their respective counter parts; (c) however, API was almost zero in mice that were nonleukemic; (d) during the natural course of leukemia, API rose significantly in almost one-half of the cases: (e) hormonal stimulation and litter numbers had no effect on API levels: (/) in contrast, transplantation exerted a rather suppressive effect on API levels; (g) API's of thymus and