Abstract
The inhibitory effect of RLP (a cell-free extract derived from sheep spleen) on radiation leukaemogenesis in mice, was studied under different biological conditions, in order to determine the limitations and specificity of its action.
For inhibition of radiation leukaemogenesis (lymphatic, thymic, type) in C57BL/6/Jax mice, the RLP injections were required to be given repeatedly — at least 4 times for demonstrable effect, and 10 times for optimal effect — the treatment begun about 1 hour after irradiation. Weaker effects were obtained when the treatment was begun 24 hours after irradiation, and no inhibition when the injections were given before the start of the radiation treatment, or begun 2 weeks after its completion.
In irradiated RF mice, RLP inhibited the induction of lymphatic (thymic) leukaemia, while that of myelogenous leukaemia appeared to be augmented.
RLP failed to inhibit the spontaneous development of the lymphatic (thymic) leukaemia in AKR mice.
The results support the conclusion that the inhibitory action of RLP is an anti-radiation effect with respect to leukaemogenesis, rather than an antagonism against the leukaemogenic process proper.
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