EFFECT OF HUMAN PREGNANCY-SPECIFIC BETA-1-GLYCOPROTEIN ON BLOOD-CELL REGENERATION AFTER BONE-MARROW TRANSPLANTATION

Pregnancy-specific beta 1-glycoprotein (PSG) is composed of a family o f highly homologous proteins initially isolated from human placenta an d pregnancy serum, Recent studies showed that PSGs are also present in a number of ectopic sites, including uncultured peripheral blood and bone marrow cells, This report aims at studying the in vivo effect of the PSGs on murine hematopoiesis. The profile of recovery of blood cel ls after transplantation of viable nucleated bone marrow cells in gamm a-irradiated mice with and without the administration of the purified human protein was studied. Five groups of mice were given 0.1 mu g hum an serum albumin, 0.1 mu g IL6, 1 mu g PSG, 10 mu g PSG, and 50 mu g P SG, respectively, per mouse per day consecutively for 20 days, The mic e were bled once every 2 days, and the platelet and WBC counts were de termined using a Nebauer hemacytometer (Hausser Scientific, Buffalo, N Y). The recovery of platelet count after bone marrow transplant was mu ch faster in mice receiving 1 mu g PSG/day than in animals in any othe r group. On Day 20 post-transplant, the platelet count of animals in t his group reached 178,600 +/- 15,759/mu l (mean +/- standard deviation ) which was significantly (P < 0.05) higher than that of any other gro up, On Day 26, the platelet count reached a low normal value of 190,84 4 +/- 6,380/mu l with a range of 185,420-200,500/mu l. This value was 3-fold higher than that of the control group (68,600 +/- 15,486/mu l i n the human serum albumin group). Mice given 1 mu g or 10 mu g PSG/day also had their WBC count recover significantly faster and achieved a normal value (12,440 +/- 3,680/mu l for the 1-mu g PSG group, and 12,1 54 +/- 3,016/mu l for the 10-mu g PSG group) within the experimental p eriod, On the other hand, the controls, or mice given 50 mu g PSG/day did not recover as rapidly and did not achieve a normal WBC count with in the experimental period. These results suggest that human placental PSGs enhance platelet and WBC recovery after bone marrow transplant.