One or more mutations in the C3H mouse background have produced a C3H/HeJ strain with absent or markedly reduced responses to endotoxin (ET) with respect to mortality, inflammatory response, production of colony-stimulating factor (CSF), and increase in in vitro granulocyte colony-forming cells. Antibody and mitogenic responses of B lymphocytes have been reported to be absent if ET extracted by the Westphal procedure (ETW) was used while present, although greatly reduced, if ET extracted by the TCA-Boivin method (ETB) was used. We have compared mortality and various hematopoietic responses to ETB and ETW in C3H/HeJ and C3HB/FeJ and C3H/HeN(CR). The lethality of HeJ mice was 0 after 1,000 or 500 micrograms ETB, while that of eB/FeJ mice was 100% for both doses and HeN was 60% after 500 micrograms and 100% after 1,000 micrograms. Hematopoietic responses were studied in irradiated and nonirradiated mice. In C3HeB/ FeJ (eB) and C3H/HeN (HeN) mice, 25 micrograms of ETW or ETB given one day before midlethal radiation between 550-800 rads produced hematopoietic responses like those previously described for normal mice of other non-C3H strains. Specifically, when ET-treated, irradiated eB or HeN mice were killed at various times after radiation, there was a 3- to 10-fold increase in endogenous spleen colony count (E-CFU), and concomitant increases in spleen weight, and in spleen iron uptake. At earlier times there was a modest increase in splenic erythroid colonies and a dramatic early wave of granulocytic spleen colonies and a dramatic early wave of granulocytic spleen colonies as compared to irradiated controls (12-40 granulocytic colonies per spleen section compared to 2-6 colonies per spleen section in irradiated controls). The recovery and overshoot of marrow granulocytes occurred four days earlier and onset of regeneration of transplantable stem cells (CFU-S) was one to two days earlier in the "normal" mice given ETB or ETW than in non-injected irradiation controls. None of these effects were seen in C3H/HeJ mice given ETW, but when they were given ETB, some of the responses were seen. These included an initial but not persistent early increase in CFU-S, increases in E-CFU, spleen weight and spleen iron uptake, and erythroid colonies in the "normal" range. There were, however, no increases in granulocytic spleen colonies and no early increase in marrow granulopoiesis in C3H/HeJ mice given ETB or ETW before irradiation.
In nonirradiated "normal" C3HeB/FeJ mice 5 micrograms ETB or ETW increased blood CSF so that approximately 60 granulocytic colonies were stimulated per 105 normal marrow cells plated and 25 micrograms ETB or ETW resulted in CSF which stimulated 155-185 colonies/105 cells plated. Blood CSF after ETB or ETW in C3H/HeJ mice stimulated no colony growth at the 5 microgram dose and only 10-13 colonies/105 of the same marrow cells plated. ETB and ETW caused "flushing" of neutrophila from the bone marrow of C3H/HeJ mice in a qualitatively normal fashion. These differences in the various hematopoietic responses will be further investigated to help determine control factors regulating hematopoiesis.