Parabiotic demonstration of a substance released from burned tissue affecting marrow megakaryocyte diameter and number in mice.

Four groups of C3H mice were studied to determine effects of substances released into blood from burned tissue on platelet counts and megakaryocyte numbers and sizes. Burns were full thickness scald injuries over 20% of body. Groups were: 1) Single, non-burned (controls); 2) Single, burned; 3) Parabiosed non-burned; 4) Parabiosed, one burned in each pair. Platelet counts and megakaryocyte counts and sizing were done at sacrifice. On 2nd postburn day platelet counts of group 4 were significantly lower (P<0.0005) than in group 1, but higher than in group 2. On day 5 platelet counts of group 4, returned to normal, then rose above normal. Two to five days postburn, megakaryocyte diameters were significantly larger in groups 2 and 4. Fifty megakaryocytes from each mouse of treatment groups were measured. A blood-borne substance(s) derived from burned tissue appears responsible for waning and waxing of megakaryocyte activity.