IN-VITRO EFFECTS OF OK-432 ON IRRADIATED MOUSE BONE-MARROW CELLS

Purpose: In vitro effects of OK-432 on irradiated mouse bone marrow ce lls are examined. Methods and Materials: Bone marrow cells of BDF1 mou se (1 X 10(6) cells/ml) were incubated with alpha medium, 2% fetal cal f serum and OK-432 in a CO2 incubator at 37 degrees C for 24, 48 and 7 2 h, respectively. After centrifugation, each supernatant was collecte d and used for conditioned medium in CFU-GM assay: Changes in CFU-GM a s a function of incubation time and OK-432 dose was examined; changes of CFU-GM according to various doses of OK-432 were examined in two mo use strains, BDF1 and BALB/c mouse; changes in protective effect of OK -432 in terms of CFU-GM as a function of administration timing of OK-4 32 in relation to irradiation. As a radiation source, Cs-137 at a dose rate of 500 cGy/min was used. Results: The CFU-GM decreased with the incubation time when OK-432 was not administered, while it significant ly increased with incubation time when OK-432 was added at 0.5 and 1.0 KE/ml at 48-72 h of incubation. The former showed marked increase at 48-72 h of incubation. CFU-GM of BDF1 mouse was always higher than tha t of BALB/c mouse for any dose of OK-432. CFU-GM per femur according t o the timing of administration of OK-432 from 24 h before to 24 h afte r irradiation showed 10299 +/- 2300 (24 h before), 10783 +/- 2463 (3 h before), 10045 +/- 1501 (immediately after), 8504 +/- 1188 (3 h after ), 4898 +/- 1212 (6 h after), 1214 +/- 736 (12 h after) and 181 +/- 11 3 (24 h after irradiation), respectively. Conclusion: OK-432 stimulate s cultured mouse bone marrow cells to produce GM-CSF in vitro by direc t contact action. This direct stimulating action of OK-432 on GM-CSF p roduction of bone marrow cells can be kept from 24 h before to at leas t 3 h after irradiation.