John C. Schooley

Inhibition by interleukin-1 of the action of erythropoietin on erythroid precursors and its possible role in the pathogenesis of hypoplastic anaemias

Summary. Highly purified and cloned preparations of interleukin‐1 (IL‐1) were found to antagonize the capacity of erythropoietin (Epo) to stimulate the proliferation of mouse spleen and bone marrow erythroid precursor cells (EPC) in culture. Cloned murine IL‐1 and purified and cloned human IL‐1α and IL‐1β were approximately equipotent in this assay. IL‐1 inhibited the proliferation response of EPC even when added as long as 17h after Epo, suggesting that IL‐1 does not affect binding of Epo to receptors or biochemical events following shortly thereafter. Indomethacin did not influence the inhibitory effect of IL‐1 on Epo‐induced proliferation, and PGE2 had no demonstrable effect on the process. Tumornecrosis factor‐α and interferons β1, and γ did not affect Epoinduced proliferation. It is suggested that IL‐1 mediated antagonism of the effects of Epo on erythroid precursors is a factor in the pathogenesis of many types of hypoplastic anaemia, including those associated with infections, rheumatoid arthritis and systemic lupus erythematosus, giant‐cell arteritis, graft‐versus‐host disease and disorders associated with lymphocyte‐mediated suppression of erythropoiesis.

Stimulation of erythropoiesis in plethoric mice by prostaglandins and its inhibition by antierythropoietin.

Summary Prostaglandins of the E series stimulated erythropoiesis in the plethoric mouse, whereas prostaglandin F2α was inactive. The erythropoietic stimulation was erythropoietin dependent, since it did not occur in antierythropoietin-injected mice.

Interactions of blood metalloproteins with nitrogen oxides and oxidant air pollutants

Abstract The effects of in vitro exposure of fresh blood and in vivo exposure of animals to atmospheres containing NO, NO2, or O3 were examined on the iron- and copper-containing proteins in whole blood by low-temperature EPR spectroscopy. Exposure of whole blood to NO under conditions in which neither free nor bound O2 is present results in the quantitative conversion of Hb to the Hb-NO derivative. Subsequent exposure of the derivative to air converts nearly all of the Hb-NO to methemoglobin in the reaction whose mechanism is detailed in this report. Nitrite seems to participate only in the terminal stages. In vivo exposure of animals to air containing a few parts per million NO or NO2 gives rise to significant accumulations of both Hb-NO and methemoglobin, the latter being the major product. This effect can be seen under typical ambient conditions. Exposure to NO2, either aerobically or anaerobically, gives rise to a mixture of Hb-NO and methemoglobin in the ratio which ranges between 1:4 and 1:20. Methemoglobin is invariably the major product. Exposure to O3, on the other hand, fails detectably to alter the state of hemoglobin in whole blood, nor does O3 generate a measurable change in organic free radicals. All three gases — NO, NO2, and O3 — significantly increase the signal due to high-spin ( S = 5 2 ) ferric catalase, while NO, NO2, and O3 all depress the level of iron transferrin. These effects translate into decreased activity for both proteins. Other metalloproteins in blood which are observable by EPR spectroscopy are, for the most part, insensitive to NO, NO2, or O3. The implications of these chemical changes in terms of health effects of NOx and oxidant air pollution are discussed.

Immunologic Studies on the Mechanism of Action of Erythropoietin.

Summary Injections into normal mice of serum obtained from rabbits previously immunized with human urinary erythropoietin results in a progressive daily decrease in the relative numbers of erythroid cells in the bone marrow. Injections of this serum into polycythemic mice 24 to 44 hours after initiation of a wave of erythropoiesis with erythropoietin has no effect on the magnitude of the erythropoietic response, although injections of the serum one hour before or at the same time that exogenous erythropoietin is administered completely abolish the erythropoietic response. These results support the concepts that erythropoietin is involved in normal regulation of red cell production and that this regulation is the result of the effect of erythropoietin on the differentiation of stem cells. Some speculative interpretations of the effect of injections of the immune serum in polycythemic mice during the first 18 hours after injection of exogenous erythropoietin are also presented.

Inhibition of erythropoietic stimulation by testosterone in polycythemic mice receiving anti-erythropoietin.

Summary The injection of testosterone into polycythemic mice produces a small but significant stimulation of erythropoiesis, as measured by Fe59 uptake into the peripheral blood, if the interval between the injection of the hormone and Fe59 is 96 hours. This stimulation of erythropoiesis is completely abolished by the injection of immune serum against the hormone erythropoietin.

Immunological neutralization of various erythropoietins.

Summary Increased serum erythropoietin levels were produced in mice, rats, rabbits, and a sheep in response to hypoxia or phenylhydrazine anemia. In all cases, including that of the rabbit, the serum erythropoietin was neutralized on addition of serum from rabbits previously immunized with an erythropoietin extract of human urinary origin. Also, an erythropoietin extract prepared from phenylhydrazine anemic sheep plasma was neutralized by such serum. These data suggest that erythropoietins of the various animal species studied are similar.

Immunochemical studies of human urinary erythropoietin.

Summary An immunochemical study of human urinary erythropoietin has been presented. The experiments indicate that the erythropoietic activity as assayed in the polycythemic mouse of erythropoietically active human urinary concentrates can be neutralized in vitro by addition of sera obtained from rabbits previously immunized with such concentrates. A significant depression of erythropoiesis was observed after injection of such sera into normal mice. It is concluded that neutralization is the result of an antigen-antibody reaction.

Stimulation of erythropoiesis in the plethoric mouse by cyclic-amp and its inhibition by antierythropoietin.

Summary The dibutyryl derivative of cyclic-AMP significantly stimulates erythropoiesis in plethoric mice. Antierythropoietin completely prevents the erythropoietic stimulation caused by cyclic-AMP, indicating that the observed erythropoietic stimulation is erythropoietin-dependent. Significant stimulation of radioiron uptake was observed in the spleens of normal mice after injection of cyclic-AMP. In addition, cyclic-AMP potentiated the erythropoietic response of plethoric mice exposed to brief periods of hypoxia.

Extrarenal Erythropoietin Production by the Liver in the Weanling Rat

Summary The ability of the weanling male and female rats to elevate their serum erythropoietin levels after a brief hypoxic exposure is significantly depressed following partial hepatectomy, and almost completely abolished following partial hepatectomy and nephrectomy.

Effects of ionizing radiation and vinblastine on the proliferation of peritoneal macrophage precursors in the mouse.

The bone marrow-derived precursors of macrophages and monocytes in inflammatory peritoneal exudates in the mouse are radiosensitive and vinblastine-sensitive cells. The degree of sensitivity to these two agents is comparable to that reported for other hematopoietic progenitor cells and for cells mediating various parameters of the immune response; this is in contrast to the known radio- and drug-resistance of the mature macrophage. The rate and timing of recovery of these macrophage precursors after 80 μg vinblastine is similar to the patterns of recovery of erythropoietin-sensitive cells after the drug.