Phytohemagglutinin (PHA), an extract of Phaseolus vulgaris, that stimulates mitosis
and morphological changes in small Iymphocytes, had been used in the treatment of
aplastic anemia by Humble (1963, 1964). Humble treated 6 patients with aplastic anemia
with PHA and reported evidence of marrow stimulation in all cases. The most
impressive improvement was observed in cases of marrow improvement due to
irradiation or cytotoxic agents.
Fleming, Retief et al., Baker and Oliver, and Gruenwa1d et al. had used PHA in
aplastic conditions with variable results. Papac also reported that mice and rats exposed
to varying doses of irradiation failed to show stimulation of marrow regeneration after
treatment with the highest tolerated doses of PHA. There does not seem to be
unequivocal evidence of myelostimulatory effect from PHA in the instances of marrow
recovery.
The present studies were undertaken as a preliminary study about hematologic
responses to PHA in rabbits which were conditioned to hypoplastic marrow by repeated
small doses of the irradiation. Here, we studied the changes of peripheral blood features
in rabbits by intraveous administrations of PHA.
Six white female rabbits, weighing 2.0∼2.5㎏, were divided as following groups:
Group I was irradiated with 60Co 500 rad. at 9th and 22nd experimental
day.
Group Ⅱ was infused daily PHA-p (Difco) 1㎖ for first 6 days intravenously and one
dose of PHA-p 1㎖ at 21st day.
Group Ⅲ was infused daily PHA-p 1 ml for first 10 days intravenously and 35th
from to 39th experimental day, and irradiated with 60Co 500 rad. at 8th
and 22nd experimental day.
The results were as follow :
1. During the infusion of PHA-p intrave nously, the hematocrit of the rabbits was
progressively decreased.
2. After infusion of the PHA-p, the reticulocyte counts were increased for several
days. This response of reticulocyte by PHA was not suppressed by the irradiation.
3. We observed in vivo Iymphocyte blast-transformation during the infusion of
PHA-p.
4. There were no changes of the numbers of white blood cells and Iymphocytes in the
normal rabbits during PHA-p infusions. There were no differences of irradiation effects
in white blood cells and Iymphocytes between PHA treated group and nontreated group.
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