ALBERT

Description: We have examined the effects of recombinant human interleukin-11 (rhIL- 11) on the recovery of peripheral blood cell counts and proliferation of progenitors and hematopoietic stem cells (day 12 colony-forming units-spleen-CFU-S12) in vivo using a mouse bone marrow (BM) and spleen cell transplantation model. Recovery of leukocytes was accelerated in animals receiving daily administration of rhIL-11 (100 micrograms/kg/d) and reached normal levels by day 14 posttransplantation. This increased total leukocyte count reflected mainly an increase in neutrophils. Neutropenia (absolute neutrophil count [ANC] 〈 1,500) was present in control transplant mice for 14 to 15 days, while in the rhIL-11-treated group, neutrophils recovered to normal by days 8 to 10 and continued to increase until day 19. Animals treated with rhIL-11 had only 1 day with ANC demonstrated 〈 500. Correspondingly, rhIL-11 treatment increased granulocyte-macrophage progenitors (CFU-GM) derived from both spleen and BM cells. Higher doses of IL-11 increased CFU-GM nearly threefold and CFU-Mix fourfold to fivefold, while increasing burst-forming units- erythroid to a lesser degree. BM and spleen cellularity were both increased in IL-11-treated mice, but no increase in CFU-S12 was noted. In addition, in vivo daily administration of IL-11 increased peripheral platelet counts by threefold over control transplant mice at day 10 posttransplantation during the post-irradiation platelet nadir. Further treatment led to platelet counts higher than normal 18 days posttransplantation when control animals had just attained normal platelet counts. IL-11 can accelerate the recovery of the peripheral blood leukocytes, mainly neutrophils, and platelets in transplant mice, effects that may be clinically useful in future applications for BM transplantation and chemotherapy-related cytopenias.

Description: Interleukin-11 (IL-11) is a bone marrow (BM) stromal-derived growth factor that has been shown to stimulate murine myeloid and lymphoid cells both in vitro and in vivo and to inhibit adipogenesis in a murine fibroblast cell line. We have studied the effects of IL-11 on highly purified human BM stem and progenitor cells and on human long-term marrow cultures (LTMC). Adipocyte differentiation is an integral component of murine and human LTMC. IL-11 stimulates myeloid growth as a single cytokine when added to highly enriched CD34+, HLA-DR+ bone marrow cells. IL-11 stimulated no growth in the more primitive CD34+, HLA-DR- population even in the presence of additional cytokines. IL-11 addition to human LTMC resulted in the expansion of myeloid and mixed, but not erythroid, progenitor populations. IL-11 dramatically increased the adherent cell populations, including both stromal cells and macrophages. Treated cultures also showed marked inhibition of fat accumulation in the adherent cells due in part to a block in the differentiation of preadipocytes to adipocytes, as shown by RNA analysis using adipocyte-specific markers. These data show that IL-11 stimulates a more differentiated, although multipotential, progenitor cell in human BM and that LTMC provide a useful model for studying the effects of this cytokine in the context of the hematopoietic microenvironment.

Description: IL-11 is a unique growth factor derived from cells making up the HM. Although cloned based on IL-6-like bioactivity, IL-11 and IL-6 have distinct biologic profiles (Table 1). IL-11, like many recently cloned growth factors, has pleiotropic effects on hematopoietic cells presumably depending on the cytokine and cellular environment into which it is introduced. However, some general findings are consistent (Table 2). In addition, IL-11 has significant effects, either primary or secondary, on nonhematopoietic cells, including neurons, small intestine crypt progenitor/stem cells, and preadipocytes. The institution of human trials with IL-11 will provide important information on the pharmacologic effects of IL-11 on human hematopoietic cells in the context of frequently used chemotherapy protocols. The physiologic role(s) of IL-11 are unknown but will become clear (at least in the mouse) with gene targeting experiments underway in several laboratories.

Description: Murine high proliferative potential colony-forming cells (HPP-CFC) are known to be heterogenous with respect to proliferative capacity and in vitro responsiveness to hematopoietic growth factors. We have separated HPP-CFC into several subpopulations using counterflow centrifugal elutriation. Although HPP-CFC were identified in all of the elutriated fractions of both C3H/HeJ and C57BI/6J bone marrow cells, the distribution of HPP-CFC as well as of colony-forming units-granulocyte- macrophage (CFU-GM) in each fraction differed between these two strains of inbred mice. Six subsets of HPP-CFC were resolved that differed in growth factor responsiveness. A low-density HPP-CFC subpopulation was isolated that was distinct from day-12 spleen colony-forming units (CFU- S12), CFU-GM, and bone marrow stromal cells. This unique subpopulation of HPP-CFC is rate (3% to 9% of total HPP-CFC), appears to be lymphocyte-like in morphology, and behaves the most primitive of the HPP-CFC subsets by requiring multiple hematopoietic growth factors for optimal in vitro cloning. Further characterization of this subpopulation of HPP-CFC will determine the position of these cells in the HPP-CFC heirarchy.

Description: Interleukin-11 (IL-11) is a bone marrow (BM) stromal-derived growth factor that has been shown to stimulate murine myeloid and lymphoid cells both in vitro and in vivo and to inhibit adipogenesis in a murine fibroblast cell line. We have studied the effects of IL-11 on highly purified human BM stem and progenitor cells and on human long-term marrow cultures (LTMC). Adipocyte differentiation is an integral component of murine and human LTMC. IL-11 stimulates myeloid growth as a single cytokine when added to highly enriched CD34+, HLA-DR+ bone marrow cells. IL-11 stimulated no growth in the more primitive CD34+, HLA-DR- population even in the presence of additional cytokines. IL-11 addition to human LTMC resulted in the expansion of myeloid and mixed, but not erythroid, progenitor populations. IL-11 dramatically increased the adherent cell populations, including both stromal cells and macrophages. Treated cultures also showed marked inhibition of fat accumulation in the adherent cells due in part to a block in the differentiation of preadipocytes to adipocytes, as shown by RNA analysis using adipocyte-specific markers. These data show that IL-11 stimulates a more differentiated, although multipotential, progenitor cell in human BM and that LTMC provide a useful model for studying the effects of this cytokine in the context of the hematopoietic microenvironment.

Description: The underlying DNA changes associated with glucose-6-phosphate dehydrogenase (G6PD)-deficient Asians have not been extensively investigated. To fill this gap, we sequenced the G6PD gene of 43 G6PD- deficient Chinese whose G6PD was well characterized biochemically. DNA samples were obtained from peripheral blood of these individuals for sequencing using a direct polymerase chain reaction (PCR) sequencing procedure. From these 43 samples, we have identified five different types of nucleotide substitutions in the G6PD gene: at cDNA 1388 from G to A (Arg to His); at cDNA 1376 from G to T (Arg to Leu); at cDNA 1024 from C to T (Leu to Phe); at cDNA 392 from G to T (Gly to Val); at cDNA 95 from A to G (His to Arg). These five nucleotide substitutions account for over 83% of our 43 G6PD-deficient samples and these substitutions have not been reported in non-Asians. The substitutions found at cDNA 392 and cDNA 1024 are new findings. The substitutions at cDNA 1376 and 1388 account for over 50% of the 43 samples examined indicating a high prevalence of these two alleles among G6PD-deficient Chinese. Our findings add support to the notion that diverse point mutations may account largely for much of the phenotypic heterogeneity of G6PD deficiency.

Description: The proliferation of epithelial cells lining the small intestinal mucosa may be regulated by microenvironmental signals leading to differentiation of precursor cells in the small intestinal crypts. Proliferation of hematopoietic cells within the hematopoietic microenvironment is known to be regulated by a growing number of glycoprotein growth factors in a hierarchial fashion. We studied the effects of administration of the microenvironment-derived hematopoietic growth factor interleukin-11 (IL-11) on mice given combination radiation/chemotherapy. Treatment of such mice with IL-11 led to significantly increased survival and evidence of rapid recovery of the small intestinal mucosa, which is severely damaged by these cytoxic agents. This recovery was associated with an increase in the mitotic index of crypt cells and an increased frequency of staining of these cells with a monoclonal antibody to proliferating cell nuclear antigen, a member of the cyclin family of nuclear antigens.

Description: Murine high proliferative potential colony-forming cells (HPP-CFC) are known to be heterogenous with respect to proliferative capacity and in vitro responsiveness to hematopoietic growth factors. We have separated HPP-CFC into several subpopulations using counterflow centrifugal elutriation. Although HPP-CFC were identified in all of the elutriated fractions of both C3H/HeJ and C57BI/6J bone marrow cells, the distribution of HPP-CFC as well as of colony-forming units-granulocyte- macrophage (CFU-GM) in each fraction differed between these two strains of inbred mice. Six subsets of HPP-CFC were resolved that differed in growth factor responsiveness. A low-density HPP-CFC subpopulation was isolated that was distinct from day-12 spleen colony-forming units (CFU- S12), CFU-GM, and bone marrow stromal cells. This unique subpopulation of HPP-CFC is rate (3% to 9% of total HPP-CFC), appears to be lymphocyte-like in morphology, and behaves the most primitive of the HPP-CFC subsets by requiring multiple hematopoietic growth factors for optimal in vitro cloning. Further characterization of this subpopulation of HPP-CFC will determine the position of these cells in the HPP-CFC heirarchy.

Description: The potent serine protease, neutrophil elastase (NE), is stored in neutrophil azurophilic granules, where it is available to degrade phagocytosed material and can be released by the cell to assist in tissue migration and help clear tissue debris. While neutrophils carry NE, they cannot produce it; the NE gene is expressed only in bone marrow granulocyte precursor cells. Protection of normal tissues from the destructive capacity of NE is provided by alpha 1-antitrypsin (alpha 1 AT), a 52-Kd serine antiprotease produced by hepatocytes and mononuclear phagocytes. In the context of the broad destructive capacity of NE, we evaluated the concept that human neutrophils may be able to modulate the extracellular activity of NE by synthesizing and secreting alpha 1AT. Immunocytochemical analysis demonstrated that the neutrophil contains alpha 1AT. Northern analysis and in situ hybridization with alpha 1AT-specific probes demonstrated the presence of alpha 1AT messenger RNA transcripts within neutrophils. [35S]methionine-labeling of neutrophils followed by immunoprecipitation of the supernatant with an anti-alpha 1AT antibody and sodium dodecyl sulfate-acrylamide gel analysis demonstrated that neutrophils can synthesize alpha 1AT de novo and secrete the synthesized molecule. In the presence of major neutrophil degranulation, the antiprotease effect of neutrophil alpha 1AT is overwhelmed, allowing the NE to act unopposed in the extracellular microenvironment. However, in conditions where small amounts of NE are released by neutrophils, at least some of the secreted newly synthesized alpha 1AT was capable of complexing with NE. Thus, despite the fact that the neutrophil cannot synthesize NE, it can synthesize and secrete alpha 1AT, the inhibitor of NE, ie, the neutrophil is capable, to some extent, of modulating NE activity in the local milieu without the help of antiproteases produced by other cells.

Description: Sera of 12 patients with quinine/quinidine-induced thrombocytopenia showed drug-dependent antibody binding to glycoprotein (GP) Ib-IX complex. The reaction with GPIb-IX complex of 11 of these 12 sera was strongly inhibited by the complex-specific monoclonal antibodies (MoAbs) AK1 and SZ1. The exception was a quinine-induced serum designated BU. The reaction of the six quinidine-induced sera was also partially blocked by an anti-GPIX MoAb, FMC25. Only 3 of the 12 patient sera showed drug-dependent antibody binding to GPIIb/IIIa, which was strongly inhibited by the anti-GPIIIa MoAb 22C4, and the anti-GPIIb alpha MoAb SZ22. With detergent-solubilized Serratia metalloprotease- treated platelets, quinine/quinidine-induced sera, except BU, immunoprecipitated a membrane-bound proteolytic fragment of GPIb-IX complex. In contrast, BU immunoprecipitated glycocalicin and a 40-Kd peptide tail fragment of GPIb alpha from the cell supernatant. Using purified GPIb-IX complex or its components as the target antigen, all the quinine-induced sera, except BU, immunoprecipitated GPIb-IX complex but failed to immunoprecipitate GPIb, GPIX, or the complex reformed from GPIb and GPIX. The quinidine-induced sera strongly immunoprecipitated purified GPIb-IX complex, weakly immunoprecipitated purified GPIX and the recombined complex, but did not immunoprecipitate purified GPIb. The combined data suggest that one quinine-dependent antibody (BU) recognizes an epitope in the peptide tail region of GPIb alpha and the other five quinine-dependent antibodies react with a complex-specific epitope on the membrane-associated region of GPIb-IX complex, whereas each of the six quinidine-induced sera contain two drug-dependent antibodies, one reactive with the GPIb-IX complex- specific epitope and the other reactive with GPIX. The binding domain(s) on GPIIb/IIIa for the quinine/quinidine-dependent antibodies appear to be sterically close to the epitopes for 22C4 and SZ22.