Changes of the blood lymphocyte population following 32P treatment for polycythemia vera

Orally administrated Na2 32PO4 mainly accumulates in bone marrow where it emits beta-particles which may damage cells. Previously, we showed that 32P treatment for polycythemia vera (PVC) increased the phytohemagglutinin reactivity and proportions of T cells in the blood. Now we have examined the effects of 32P treatment for PCV on natural killer (NK) and B-lymphocyte subsets which are considered to undergo their maturation in bone marrow. A mean isotope dose of 240 MBq given to 14 patients reduced the peripheral lymphocyte counts to 60% at 6 weeks. B cells and NK cells were reduced to the highest relative extent followed by HNK-1 cells and T cells. Although the proportion of NK cells was reduced to 50% there was no concomitant reduction of NK activity against K562 cells. Pokeweed mitogen-triggered secretion of IgM was significantly reduced, but not that of IgG or IgA. It is suggested that lymphocytes which mature in bone marrow may be affected to the highest extent by 32P treatment in PCV.