Release of colony-stimulating activity from thymus-derived lymphocytes

Altered plasma levels of βC and γC chain cytokines and post-treatment modulation in tuberculous lymphadenitis

BACKGROUND

Alterations in β common (βC) and γ common (γC) chain cytokines have been described in pulmonary tuberculosis. However, their role in tuberculous lymphadenitis (TBL) disease has not been assessed.

METHODS

Thus, in the present study, we have examined the systemic levels of βC and γC chain cytokines in TBL, latent tuberculosis (LTB) and healthy control (HC) individuals. We have examined the discriminatory potential of both family of cytokines using ROC analysis. Finally, we measured the pre and post-treatment responses of these cytokines after anti-tuberculosis treatment.

RESULTS

TBL individuals exhibit significantly increased (IL-3) and diminished systemic levels of (IL-5, GM-CSF) βC cytokines compared to LTB and HC individuals. TBL individuals also exhibit significantly diminished (IL-2, IL-7) and elevated (IL-4, IL-9) levels of γC cytokines compared to LTB and/or HC. ROC analysis shows a clear discriminatory capacity of both βC (IL-5) and γC (IL-2) chain cytokines to distinguish TBL from LTB and HCs. The systemic levels of βC chain cytokines were not significantly altered, but in contrast γC (IL-2 and IL-7) cytokines were significantly modulated after treatment. Finally, no significant correlation was observed for βC and γC chain cytokines with their respective lymphocyte count of TBL individuals.

CONCLUSIONS

Hence, we conclude that altered plasma levels of βC and γC cytokines are the characteristics of immune alteration in TBL disease and certain cytokines were modulated after treatment.

Role of Granulocyte-Macrophage Colony-Stimulating Factor Production by T Cells during Mycobacterium tuberculosis Infection

Mice deficient for granulocyte-macrophage colony-stimulating factor (GM-CSF^−/−) are highly susceptible to infection with Mycobacterium tuberculosis, and clinical data have shown that anti-GM-CSF neutralizing antibodies can lead to increased susceptibility to tuberculosis in otherwise healthy people. GM-CSF activates human and murine macrophages to inhibit intracellular M. tuberculosis growth. We have previously shown that GM-CSF produced by iNKT cells inhibits growth of M. tuberculosis. However, the more general role of T cell-derived GM-CSF during infection has not been defined and how GM-CSF activates macrophages to inhibit bacterial growth is unknown. Here we demonstrate that, in addition to nonconventional T cells, conventional T cells also produce GM-CSF during M. tuberculosis infection. Early during infection, nonconventional iNKT cells and γδ T cells are the main source of GM-CSF, a role subsequently assumed by conventional CD4⁺ T cells as the infection progresses. M. tuberculosis-specific T cells producing GM-CSF are also detected in the peripheral blood of infected people. Under conditions where nonhematopoietic production of GM-CSF is deficient, T cell production of GM-CSF is protective and required for control of M. tuberculosis infection. However, GM-CSF is not required for T cell-mediated protection in settings where GM-CSF is produced by other cell types. Finally, using an in vitro macrophage infection model, we demonstrate that GM-CSF inhibition of M. tuberculosis growth requires the expression of peroxisome proliferator-activated receptor gamma (PPARγ). Thus, we identified GM-CSF production as a novel T cell effector function. These findings suggest that a strategy augmenting T cell production of GM-CSF could enhance host resistance against M. tuberculosis.

Mycobacterium tuberculosis is the bacterium that causes tuberculosis, the leading cause of death by any infection worldwide. T cells are critical components of the immune response to Mycobacterium tuberculosis. While gamma interferon (IFN-γ) is a key effector function of T cells during infection, a failed phase IIb clinical trial and other studies have revealed that IFN-γ production alone is not sufficient to control M. tuberculosis. In this study, we demonstrate that CD4⁺, CD8⁺, and nonconventional T cells produce GM-CSF during Mycobacterium tuberculosis infection in mice and in the peripheral blood of infected humans. Under conditions where other sources of GM-CSF are absent, T cell production of GM-CSF is protective and is required for control of infection. GM-CSF activation of macrophages to limit bacterial growth requires host expression of the transcription factor PPARγ. The identification of GM-CSF production as a T cell effector function may inform future host-directed therapy or vaccine designs.

Effects of Carnosine on Cyclophosphamide-Induced Hematopoietic Suppression in Mice

Cyclophosphamide is one of the most widely used chemotherapeutic agents in treating cancers. Chemotherapy drug-induced oxidative stress produces side effects. The severity of myelosuppression increases with a high dose of cyclophosphamide. Chicken soup or chicken essence, a traditional Chinese aliment, is a popular health supplement for patients with cancers or other diseases in Asia. As a major functional component of chicken meat extract, carnosine (beta-alanyl-L-histidine), a dipeptide of the amino acids beta-alanine and histidine, has been shown to have strong antioxidant activities. In the present study, we investigated the effects of carnosine on hematopoietic suppression in mice treated with cyclophosphamide. As expected, we found that cyclophosphamide administration (with a single dose of 150 mg/kg) induced a rapid (within 24 hours) and severe hematopoietic suppression in mice. We further showed that carnosine administration (100 mg/kg/day or 200 mg/kg/day for continuous seven days) could substantially improve suppressed hematopoietic functions and accelerate the recovery of leukocyte counts, bone marrow spontaneous proliferation, colony stimulating activity (CSA) in serum, and production of endogenous cytokines such as interleukin-3 (IL-3) and stem cell factor (SCF). These results indicate that carnosine has the potential to promote the recovery from hematopoietic suppression induced by cyclophosphamide. Our data suggest that carnosine holds a potential in clinical application to minimize the side effects induced by chemotherapeutic agents such as cyclophosphamide and thus will substantially improve the overall anti-tumor effects of the standard chemotherapies.

Can 29kDa rhGM-CSF expressed by Silkworm pupae bioreactor bring into effect as active cytokine through orally administration?

In order to study the effect of human granulocyte-macrophage colony-stimulating factor (hGM-CSF) as active cytokine through orally administration, we expressed hGM-CSF within silkworm pupae bioreactor. The purified rhGM-CSF named as BmrhGM-CSF is characterized as 29kDa glycoprotein, and its biological activity was measured both in vitro and in vivo. We found out BmrhGM-CSF could stimulate the colony formation of human bone marrow cells in a dose-dependent manner whether which were treated with or without gamma-ray 24h before. The ability of colony formation induced by BmrhGM-CSF is negatively correlated with gamma-ray intensity. As soon as 15min post oral administration with BmrhGM-CSF labeled with (125)I, an approximately 20kDa protein fragment was detected within mice blood by SDS-PAGE followed by autoradiography. In blood sample of test mice, a protein was also recognized by anti-hGM-CSF antibody using ELISA. The immunohistochemical analysis showed that BmrhGM-CSF was detected within intestinal histiocyte. This indicated it might be absorbed into blood via intestinal microvillus. Pharmacokinetics analysis after orally administered BmrhGM-CSF in animal model of leucopenia including mice, Beagle dogs and macaques showed that: (1) BmrhGM-CSF promoted the CFU-S formation in mice spleen and the synthesis of DNA in bone marrow cells of mice; (2) BmrhGM-CSF induced bone marrow karyocyta granulocyte growth significantly in both macaques and Beagle dogs compared to the negative control group. On the 9th day of orally administration, the animal WBC significantly increased in a dose-dependant manner, in which neutrophilic granulocyte was predominant. The WBC level of dogs in high dose group was about 1.5x10(9)cells/L more than that in the negative control. And the bone marrow smear revealed that the percents of both myloblast and progranulocyte in WBC in the hGM-CSF group were obviously higher than those in the negative control. These results proved that BmrhGM-CSF, a 29kDa glycoprotein expressed by Silkworm pupae bioreactor, could bring into the effect as active cytokine through oral administration.

Immobilization of antibodies onto glass wool

The immobilization of antibodies onto solid phases in an efficient and activity-retaining form is an important goal for both research and industry. Methods have been developed for the site-directed attachment of antibodies to agarose by oxidation of the carbohydrate moieties in their Fc region. Similar attachment to silianized supports have not been as successful. Here we describe a novel combination protocol for the site-directed attachment of periodate oxidized, goat polyclonal antibodies to glass wool fibers activated with 3-aminopropyltriethoxysilane. The study demonstrates that this procedure results in effective immobilization of polyclonal antibodies that retain their antigen-binding capacity. This protocol should prove useful in the development of more efficient and effective glass-based immunosupports.

Interleukin-10 Inhibits Spontaneous Colony-Forming Unit–Granulocyte-Macrophage Growth From Human Peripheral Blood Mononuclear Cells by Suppression of Endogenous Granulocyte-Macrophage Colony-Stimulating Factor Release

Spontaneous growth of myeloid colonies (colony-forming unit–granulocyte-macrophage [CFU-GM]) can be observed in methylcellulose cultures containing peripheral blood mononuclear cells (PB-MNCs) and is supposedly caused by the release of colony-stimulating factors (CSF ) by accessory cells. Because of its cytokine synthesis-inhibiting effects on T lymphocytes and monocytes, interleukin-10 (IL-10) may be a potential candidate for indirect modulation of hematopoiesis. We studied the effect of recombinant human IL-10 (rhIL-10) on spontaneous growth of myeloid colonies derived from human PB-MNCs. A total of 10 ng/mL of IL-10 almost completely inhibited spontaneous CFU-GM proliferation (by 95.1%; P < .001, n = 7) in unseparated PB-MNCs. This effect was dose-dependent and specific, because a neutralizing anti–IL-10 antibody was able to prevent IL-10–induced suppression of CFU-GM growth. Spontaneous CFU-GM growth, which required the presence of both monocytes (CD14+ cells) and T lymphocytes (CD3+ cells), was also greatly suppressed by a neutralizing anti–granulocyte-macrophage CSF (GM-CSF ) antibody but was only slightly or not at all inhibited by antibodies against G-CSF or IL-3. Moreover, IL-10–suppressed colony growth could be completely restored by the addition of exogenous GM-CSF. Using semiquantitative polymerase chain reaction, we were able to show that GM-CSF transcripts that spontaneously increased in PB-MNCs within 48 hours of culture were markedly reduced by the addition of IL-10. Inhibiton of GM-CSF production in PB-MNCs by IL-10 was also confirmed at the protein level by measuring GM-CSF levels in suspension cultures. Our findings suggest that autonomous CFU-GM growth, resulting from an interaction of monocytes and T lymphocytes, is mainly caused by endogenous GM-CSF release and can be profoundly suppressed by the addition of exogenous IL-10. Considering the strong inhibitory action of IL-10 on GM-CSF production and spontaneous cell growth in vitro, this cytokine may be useful in myeloid malignancies in which autocrine and/or paracrine mechanisms involving GM-CSF are likely to play a pathogenetic role.

Levels of human serum granulocyte colony-stimulating factor and granulocyte-macrophage colony-stimulating factor under pathological conditions

Levels of serum granulocyte colony-stimulating factor (G-CSF) and granulocyte-macrophage colony-stimulating factor (GM-CSF) in patients with various leukocyte disorders were estimated by enzyme-linked immunosorbent assay (ELISA). Some cases of acute myelogenous leukemia and aplastic anemia showed elevated serum levels of G-CSF and/or GM-CSF, whereas almost all of 23 healthy controls showed G-CSF and GM-CSF levels lower than 100 pg/ml. High levels of both types of CSF were noted in patients with granulocytosis due to infection. These levels became lower after resolution of the infection. Daily changes in serum CSF levels were also examined in a patient with autoimmune neutropenia, and it was found that the peripheral neutrophilic granulocyte count changed almost in parallel with the serum G-CSF level but not with GM-CSF, following the pattern with a delay of about 4-5 h, suggesting the possibility that G-CSF mainly regulates peripheral neutrophil circulation.

The Inflammatory Response

Inflammation is a critical component of the normal healing process. In the patient with extensive injury or infection, however, this same process may lead to organ dysfunction and failure as seen in adult respiratory distress syndrome and multiple organ failure syndrome. In this article we review: (1) the evolution of current concepts of inflammation; (2) individual elements of the host response to inflammatory stimuli; and (3) current strategies for the prevention and treatment of adult respiratory distress syndrome and multiple organ failure syndrome.

From the Department of Surgery, University of Washington School of Medicine, Harborview Medical Center, Seattle, WA.

Augmentation of granulocyte/macrophage colony-stimulating factor expression by ultraviolet irradiation is mediated by interleukin 1 in Pam 212 keratinocytes

Keratinocytes are a potent source of a variety of cytokines including granulocyte-macrophage colony-stimulating factor (GM-CSF). In this study, we have shown that ultraviolet B (UVB) irradiation augments GM-CSF mRNA expression by murine keratinocytes. This is reflected in the increased production of GM-CSF protein by these cells. In the same cell population, exposure to UVB irradiation increases interleukin 1 alpha (IL-1 alpha) mRNA and IL-1 protein as detected by bioactivity. This increase in IL-1 alpha precedes the increase of GM-CSF mRNA. Addition of recombinant IL-1 alpha to the medium increases GM-CSF mRNA expression. Anti-IL-1 alpha antibodies can completely inhibit UV-augmented GM-CSF mRNA expression. These results demonstrate that UVB irradiation-induced augmentation of GM-CSF is mediated by UV-induced IL-1 alpha.

Interleukin 1 and tumor necrosis factor-alpha additively increase the levels of granulocyte-macrophage and granulocyte colony-stimulating factor (CSF) mRNA in human fibroblasts

Recombinant interleukin (IL) 1 beta and tumor necrosis factor/cachectin (TNF-alpha) induce, usually within 2 h, a dose-dependent increase in the levels of granulocyte-macrophage colony-stimulating factor (GM-CSF) and G-CSF mRNA in cultured human fibroblasts. Maximal induction is reached at about 4-8 h and usually last for at least 48 h. IL 1 beta and TNF have additive effects on the levels of GM- and G-CSF mRNA, and on the secretion of G-CSF activity into the culture medium. IL 1 alpha has the same additive effect that IL 1 beta has with TNF, but no additive effect with IL 1 beta. In contrast, the high basic level of M-CSF (CSF-1) mRNA shows little or lower variations in response to IL 1, TNF-alpha or both IL 1 and TNF-alpha also induce, with similar kinetics, an increase in IL 1 beta but not mRNA level. In contrast to what is observed with macrophages and endothelial cells, E. coli lipopolysaccharide does not modify the fibroblast CSF mRNA level up to 48 h of culture.

Interleukin 1 stimulates granulocyte macrophage colony-stimulating activity release by vascular endothelial cells

Studies designed to characterize monocyte-derived recruiting activity (MRA) a monokine that stimulates endothelial cells to produce granulocyte macrophage-colony-stimulating activity (CSA) by endothelial cells, show that it is a thermolabile protein of from 12,000 to 24,000 D which, on chromatofocusing, shows three separate peaks of eluted activity from pH 7.5 to 5.0. Because these and many other properties of MRA are identical to those of interleukin 1 (IL-1), we tested the hypothesis that MRA and IL-1 are identical. We cultured vascular endothelial cells with various concentrations of purified native and recombinant IL-1 (pI 7 form), then tested the endothelial cell supernatants for GM-CSA. Purified native IL-1 and recombinant IL-1 stimulated endothelial cells to release CSA. The MRA of native IL-1, recombinant IL-1, and unfractionated monocyte conditioned medium was neutralized by a highly specific rabbit anti-human IL-1 antiserum. Chromatofocusing fractions that contained MRA contained immunoreactive IL-1 on immunoblotting and the bioactivity was neutralized completely by treatment with the antiserum. We conclude that IL-1 induces the release of CSA by vascular endothelial cells, that IL-1 is constitutively produced by monocytes in vitro, and that MRA and IL-1 are biologically, biophysically and, immunologically identical.

The role of eosinophil in regulation of granulopoiesis

An association between eosinophilia and neutropenia has been observed in a number of clinical conditions. To probe the role of eosinophils in granulopoiesis, marrow and peritoneal eosinophils, obtained from Schistosoma mansoni-infected mice, were separated and purified. Normal bone marrow cells were cultured in semi-solid culture medium in concentrations ranging from 5 X 10(4) to 5 X 10(5), with and without added eosinophils. To examine whether high prostaglandin E (PGE) content of eosinophils affects granulopoiesis, indomethacin was added to duplicate marrow cultures containing eosinophils. The addition of eosinophils to normal syngeneic marrow culture caused a significant inhibition of granulocyte-macrophage colony formation (CFU-GM) in culture. This suppressive effect was reversible upon addition of indomethacin. These findings suggest that eosinophils, in vitro, are capable of inhibition of granulopoiesis. The reversal of this effect by indomethacin indicates that this suppression may be prostaglandin mediated.

Gamma interferon and lymphotoxin, released by activated T cells, synergize to inhibit granulocyte/monocyte colony formation

We have shown that lymphocytes stimulated by PHA produce colony-forming unit of granulocyte/monocyte (CFU-GM)-stimulating and -inhibiting activities, IFN-gamma, and lymphotoxin (LT). IFN-gamma is necessary for inhibition of CFU-GM by PHA-conditioned medium (CM), as shown by experiments in which removal of IFN-gamma from PHA-CM abrogated inhibition. However, experiments in which rIFN-gamma was added to IFN-gamma-depleted PHA-CM revealed the presence, in PHA-CM, of other factors that act in synergy with IFN-gamma to inhibit CFU-GM. Fractionation of PHA-CM on a Sephadex G-100 column was used to separate IFN-gamma and LT. Colony-inhibiting activity was eluted in fractions that contained both IFN-gamma and LT activities, identifying LT as a factor present in PHA-CM that synergizes with IFN-gamma to inhibit CFU-GM. Treatment of PHA-CM with mAb against either IFN-gamma or LT completely abrogated the colony-inhibiting activity, demonstrating a requirement for both lymphokines in PHA-CM-induced inhibition of CFU-GM. Experiments using rIFN-gamma and preparations of purified LT confirmed that neither lymphokine alone, when added to bone marrow cells at the concentrations present in PHA-CM, strongly inhibited day 7 or day 14 CFU-GM, but that the two lymphokines, added together, behaved synergistically to inhibit CFU-GM by up to 70%. The inhibition observed using purified preparations of lymphokines shows that synergy between IFN-gamma and LT is sufficient to explain PHA-CM-induced inhibition of CFU-GM. Our findings suggest that activated T cells regulate hematopoiesis through the release of inhibitory as well as stimulatory factors, and that the simultaneous production of IFN-gamma and LT may represent a mechanism of suppression of hematopoiesis in the cases of bone marrow failure associated with the presence of activated T cells.

Interleukin 1 stimulates fibroblasts to produce granulocyte-macrophage colony-stimulating activity and prostaglandin E2

Granulocyte-macrophage colony-stimulating activity (GM-CSA) can be produced by a variety of normal cell types including mononuclear phagocytes, activated T lymphocytes, endothelial cells, and fibroblasts. Recent evidence shows that a major role of the monocyte-macrophage is the recruitment of environmental cells, i.e., fibroblasts, to produce GM-CSA. In this study we have identified interleukin 1 (IL-1) as a monokine that stimulates fibroblasts to produce and release GM-CSA and prostaglandin E2 (PGE2). Both purified human monocyte-derived IL-1 and human recombinant IL-1 (10(-10) M) can be substituted for monocyte-conditioned medium in stimulating fibroblast GM-CSA and PGE2 production. Both forms of IL-1 stimulate fibroblasts to produce GM-CSA and PGE2 in a dose-dependent fashion. The fibroblast-stimulating activity found in monocyte-conditioned medium was completely blocked by anti-IL-1. We conclude that monocytes produce IL-1, and that monocyte-derived IL-1 induces fibroblasts to produce GM-CSA and PGE2.

Lactoferrin: its role as a regulator of human granulopoiesis?

Lactoferrin has been proposed recently as a physiological regulator of the granulocyte-monocyte progenitor (CFU-GM). This glycoprotein, when saturated with iron, has been said to limit the CFU-GM growth by decreasing production and release of colony stimulating activity by monocytes and macrophages. Human milk lactoferrin saturated with iron, at concentrations ranging from 10(-8) M, was added either to endogenously stimulated bone marrow cells or to mononucleated cells used as feeder layers for adherent cell-depleted marrow. Irrespective of the concentration of lactoferrin within the culture system used, no significant inhibition of the CFU-GM growth was observed. Moreover, the CFU-GM stimulating activity of medium conditioned by a 4 day incubation of 1 X 10(6) mononucleated blood cells in the presence or in the absence of lactoferrin was the same. Various possible explanations for not confirming the reported inhibiting activity of iron-saturated lactoferrin were explored: (a) masking inhibition of the system by prostaglandin E2 (PGE2), (b) masking inhibition of the system by bovine lactoferrin present in the fetal calf serum, (c) preinhibition of the system by leukemic-associated inhibitory activity possibly present in the culture system, (d) the iron and calcium content of the culture medium used, (e) the fixation of lactoferrin to plastic compounds, (f) the source of the human lactoferrin used, and (g) the marrow cell separation methods used. None of these factors was shown to play a role in vitro in the activity of lactoferrin and thus no evidence was found for a significant role of lactoferrin in the regulation of human granulopoiesis.

Immune regulation of in vitro murine megakaryocyte development. Role of T lymphocytes and Ia antigen expression

Mitogen-activated murine T lymphocytes or T cell hybridomas produce an activity (megakaryocyte [Mk] potentiator activity) that enhances the in vitro growth and development of Mk colonies. This activity was found in optimal concentrations (2.5%) in T cell hybridoma-conditioned medium, and was also produced by feeder layers of concanavalin A-activated T cells. A subpopulation of murine Mk progenitor cells (colony-forming units; CFU-Mk) bears the Ia antigen. Separate experiments indicated that T cell products stimulate CFU-Mk by increasing their basal levels of Ia expression as well as the frequency of cells actively synthesizing DNA. The hypothesis that the expression of this antigen was related to the cell cycle status of these progenitor cells was confirmed in studies that indicated that ablation of actively cycling cells in vivo abrogated the cytotoxic effects of anti-Ia monoclonal antibodies. The interdependence of T cell lymphokine regulation of both Ia expression and cell cycle status was also seen in in vitro experiments in which Ia+ progenitor cells were eliminated by complement-dependent cytotoxicity. The removal of Ia+ cells prevented 5-hydroxyurea-mediated inhibition of cells in S phase. We hypothesize that immune modulation of megakaryocytopoiesis occurs via soluble T cell products that augment Mk differentiation. Further, the mechanism of immune recognition/modulation may occur via Ia antigens present on the surface of these progenitor cells.

Release of granulocyte-macrophage colony-inhibiting activity by normal human postthymic precursor cells

Seven normal human peripheral blood cell fractions (buffy coat, mononuclear cells, non-T, T, Fc-IgM receptor-depleted T-lymphocyte, Fc-IgG receptor-depleted T-lymphocyte, and autologous rosette-forming T-cell-depleted T-lymphocyte subpopulations) treated with phytohemagglutinin (PHA) were examined for the production of granulocyte-macrophage colony-stimulating activity (CSA). It was found that medium conditioned by a T-lymphocyte subpopulation depleted of autologous rosette-forming T-cells (Tar cells, a postthymic precursor subpopulation that inhibits Ig synthesis) stimulated colony-forming units of granulocyte and macrophages (CFU-GM) to a greater extent than did the other conditioned media (CM) analyzed. Based on this finding, CM from an enriched Tar subpopulation was prepared and thus showed that PHA-treated Tar cells release a factor capable of inhibiting CFU-GM growth. The inhibitory activity of this factor persisted-after heat inactivation, suggesting that cause of the colony-inhibiting activity (CIA) is other than interferon. Further studies revealed that Tar-derived inhibitory factor acts either directly upon CFU-GM or via monocytes/macrophages (M phi/Ma), enhancing CIA, and not the level of CSA production by M phi/Ma. The overall data are interpreted as demonstrating the presence of CIA in a specific T-lymphocyte subpopulation that may represent a new relationship between lymphocytic and myelocytic systems in the human.

Thymosin alpha 1 exerts protective effect against the 5-FU induced bone marrow toxicity

Thymosin alpha 1 was shown to prevent the 5-fluorouracil(5-FU)-induced bone marrow toxicity in BDF1 mice, as determined by the cellularity, haemopoietic stem cells (CFU-s) and granulocyte-macrophage colony forming unit (GM-CFU). Furthermore, thymosin alpha 1 increased the levels of colony stimulating factor (CSF) in sera or in culture media of spleen cells derived from 5-FU-treated mice. The treatment of spleen cells with anti-Thy 1,2 antibody plus complement abolished completely the CSF production. The in vivo treatment of donor mice with anti-Thy 1,2 antibody following 5-FU abolished completely the capability of their bone marrow cells to save lethally irradiated recipients. Thymosin alpha 1 treatment prevented the damage by such combined treatment. The present study indicates that thymosin alpha 1 exerts its protective effect against the 5-FU-induced bone marrow toxicity, at least partially, through its effect on the maturation of immature T cells to functional T cells which produce various kinds of lymphokines including CSF.

Release of hemopoietic factors by normal human T cell lines with either suppressor or helper activity

We analyzed the release of activities capable of stimulating the in vitro growth of human hemopoietic progenitor cells by long-term cultured T cell growth factor (TCGF)-dependent human T lymphocytes. Seven cell lines tested produced colony-stimulating activity (CSA) as well as burst-promoting activity (BPA). The CSA stimulated primarily the growth of the cells forming colonies after 14 days of incubation. In addition the supernatants from these seven T-cell lines showed the ability to induce the in vitro growth of mixed granulocyte, erythroid, megakaryocyte, macrophage colonies (CFU-GEMM). The release of hemopoietic factors did not depend on the presence of accessory cells or phytohemagglutinin or serum during the incubation for factor production. In six of the T cell lines the majority of the cells were reactive to the OKT 8 monoclonal antibody (MoAb), whereas one cell line contained mostly OKT 4+ cells. Suppressor activity was detected in three tested OKT 8+ cell lines, while the one OKT 4+ displayed helper activity. All cell lines produced hemopoietic factors with equal efficiency. These results indicate that factors affecting human hematopoiesis are produced by normal T lymphocytes in long-term culture and this property is not related to the helper or suppressor activity of the cultured cells.

Modulation of myelopoiesis by CSF or CSF-inducing biological response modifiers

We have compared the effects on number and function of bone marrow progenitors and peripheral effector cells of the myelomonocytic lineage of treatment with the 2-cyanaziridine compounds Azimexone and BM 41.332 to those of maleic anhydride divinyl ether copolymer (MVE-2) or granulocyte-macrophage colony stimulation factor (GM-CSF). Within a few hours after i.p. injection of either Azimexone or BM 41.332, there was a dose-dependent increase in serum CSF levels, CSF secretion by mononuclear bone marrow cells (BMC) and macrophages (M phi), which was followed by an increase in granulocyte-M phi committed stem cells (GM-CFU-C), nucleated BMC, and peripheral blood leukocytes. Optimal effects occurred 3 days after 50 mg/kg Azimexone or 25 mg/kg BM 41.332. Three i.p. injections of 50 mg/kg Azimexone into mice pretreated with cyclophosphamide (CY) (150 mg/kg) were able to significantly restore suppressed bone marrow cellularity (GM-CFU-C and nucleated BMC). Azimexone also increased the number of peripheral M phi in normal or CY-treated mice, without inducing detectable tumoricidal activity. These M phi, however, retained their capacity to become fully activated (cytotoxic) by appropriate activation signals such as IFN or LPS. Analogous to the 2-cyanaziridines. MVE-2 (at 25 mg/kg) had similar stimulatory effects on myeloid functions in normal mice. MVE-2 induced, in addition, a significant augmentation of cytoxicity by both M phi and NK cells. In contrast, single or multiple injections of semipurified GM-CSF into normal mice (1000 U or 5000 U per mouse) failed to detectably stimulate myelopoietic growth and differentiation. 2-cyanaziridine compounds thus offer the potential of selectively augmenting growth and differentiation of myelomonocytic cells in normal and bone marrow-depressed mice without appreciably affecting their immunological status.

Pathology-important advances in clinical medicine: assessing fetal lung maturity

The Scientific Board of the California Medical Association presents the following inventory of items of progress in pathology. Each item, in the judgment of a panel of knowledgeable physicians, has recently become reasonably firmly established, both as to scientific fact and important clinical significance. The items are presented in simple epitome and an authoritative reference, both to the item itself and to the subject as a whole, is generally given for those who may be unfamiliar with a particular item. The purpose is to assist busy practitioners, students, research workers or scholars to stay abreast of these items of progress in pathology that have recently achieved a substantial degree of authoritative acceptance, whether in their own field of special interest or another.The items of progress listed below were selected by the Advisory Panel to the Section on Pathology of the California Medical Association and the summaries were prepared under its direction.

Comparison of in vitro and in vivo modulation of myelopoiesis by biological response modifiers

In vitro growth and differentiation of granulocyte-macrophage progenitor cells (GM-CFU-C) requires colony-stimulating factors (CSF), and an in vivo role for CSF has also been proposed. Prostaglandins of the E series (PGE) have been reported to serve as negative feedback regulators of myelopoiesis. Here, we report evidence of augmented CSF secretion by mouse peritoneal Mo (macrophages) and bone marrow cells in vitro upon stimulation with various biological response modifiers (BRMs). Optimal induction of CSF secretion occurred after in vitro treatment of peritoneal Mo and mononuclear bone marrow cells with 50 micrograms/ml poly ICLC (polyriboinosinic-polycytidylic acid poly-L-lysine). 5 micrograms/ml lipopolysaccharide (LPS), or 500 U/ml interferon (IFN alpha,beta) for 2 days. The in vitro stimulation of CSF secretion was paralleled by an increase in PGE secretion by Mo and bone marrow cells. The PGE secretion could, however, be selectively blocked by preincubating the cells for 3 h with indomethacin (10(-7) Mol) leaving CFS production intact. In vivo treatment of mice with either maleic anhydride divinyl ether copolymer (MVE-2; 25 mg/kg) or poly ICLC (2 mg/kg) significantly increased levels of CSF in serum, as well as in culture supernatants of in vivo-treated peritoneal Mo and bone marrow cells. The increase in serum CSF levels and in secretion of CSF by peritoneal Mo and bone marrow cells was followed by a dose-dependent increase in GM-CFU-C, in nucleated bone marrow cells, and in peripheral blood leukocytes. The same BRMs also stimulated the secretion of PGE by in vivo-activated peritoneal Mo, but not by bone marrow cells. Pretreatment of the mice with indomethacin (4 mg/kg) almost completely suppressed PGE secretion by peritoneal Mo, but did not change the CSF secretion by peritoneal Mo or bone marrow cells and had no significant effect on bone marrow cellularity. Therefore, MVE-2 and poly ICLC, in addition to their immunomodulatory activity, can also have stimulatory effects on myelopoiesis, presumably mediated through secretion of CSFs. Protection and/or restoration of bone marrow function could thus either provide the opportunity for more extensive chemotherapy or could increase the number of Mo effector cells available for activation against tumor targets.

Role of prostaglandin E and interferon in secretion of colony-stimulating factor by murine macrophages after in vitro treatment with biological response modifiers

We have evaluated the possible role of biological response modifiers (BRMs) in myelopoiesis by investigating BRM modulated secretion of hematopoietic growth factors and inhibitors. Here, we report the evidence of augmented secretion of granulocyte and/or macrophage colony stimulating factors (CSF) by murine resident peritoneal macrophages after in vitro incubation with murine interferons (alpha, beta-mIFN; beta-mIFN; gamma-mIFN), poly ICLC (polyriboinosinic-polycytidylic acid poly-L-lysine), BM 41.332 (2-cyano-1-[(2-methoxy-6-methyl-pyridin-3yl)-methyl]-aziridine) and lipopolysaccharide (LPS). The secretion of CSF appears to be independent of the ability of the BRMs to induce IFN, as shown by the use of neutralizing antibodies against mIFN. The antiproliferative effects of IFN also did not block the BRM induced effects of CSF. The combination of alpha, beta-mIFN and poly ICLC or LPS and poly ICLC at suboptimal concentrations resulted in additive, but not synergistic effects on CSF secretion by macrophages. Histological examination of the colonies induced indicated the presence of two types of CSF, namely CSF1 and CSF3, which give rise to pure macrophage and granulocyte colonies respectively. In parallel to their effect on CSF secretion, these BRMs also caused a considerable increase in secretion of prostaglandins of the E series (PGE) by macrophages. However, the production of PGE did not interfere or influence CSF secretion, since the inhibition of the enzyme cyclooxygenase with indomethacin (10(-7) molar) 3 h before stimulation with poly ICLC, alpha, beta-mIFN, or LPS, inhibited the secretion of PGE by macrophages without affecting the secretion of CSF. Macrophages, stimulated by one of the active BRMs for 24 h, could not be restimulated by any of these agents to again secrete significant amounts of CSF or PGE, even after a 2 day resting phase. Other drugs tested (diethyldithiocarbamate, maleic anhydride divinyl ether, azimexone) failed to stimulate the in vitro secretion of significant amounts of CSF and PGE. The results presented here indicate that several BRMs can be utilized to stimulate macrophages to secrete the myelopoietic growth factor CSF, thus supporting the concept that these BRMs might be of value in reconstituting or promoting impaired granulocyte and monocyte/macrophage function.

Regulation of colony-stimulating activity production. Interactions of fibroblasts, mononuclear phagocytes, and lactoferrin

Neonatal skin fibroblasts were cultured in supernatants of peripheral blood monocytes that had been cultured with and without lactoferrin. Granulocyte-monocyte colony-stimulating activity (CSA) was measured in supernatants of the fibroblast cultures with normal T lymphocyte-depleted, phagocyte-depleted, low density bone marrow target cells in colony growth (colony-forming unit granulocyte/macrophage) assays. Monocyte-conditioned medium contained a nondialyzable factor that enhanced by 17-50-fold the production of CSA by fibroblasts. The addition of lactoferrin to monocyte cultures reduced the activity of this monokine by 75-100%. Lactoferrin did not inhibit CSA production by monokine-stimulated fibroblasts. We conclude that under appropriate conditions human fibroblasts are potent sources of CSA, that the production of CSA by these cells is regulated by a stimulatory monokine, and that the production and or release of the monokine is inhibited by lactoferrin, a neutrophil-derived putative feedback inhibitor of granulopoiesis. We propose that the major role of mononuclear phagocytes in granulopoiesis is played not by producing CSA, but by recruiting other cells to do so, and that in the steady state, feedback regulation of neutrophil production may occur as a result of a mechanism that inhibits the recruitment phenomenon.

Monocyte-macrophage modulation of T-lymphocyte-derived colony-stimulating activity elaboration in man

To investigate the source and the mechanisms of synergistically enhanced colony-stimulating activity elaboration by the coincubated monocyte-macrophages and T lymphocytes, we simultaneously prepared conditioned media both from the coincubated monocyte-macrophages and T lymphocytes (ratio 1:3) in the presence of phytohemagglutinin (1%) or methanol extraction residue of bacillus Calmette-Guerin (50 micrograms/ml) and from the isolated T lymphocytes that had been primed with monocyte-macrophages in the presence or absence of phytohemagglutinin or methanol extraction residue of bacillus Calmette-Guerin. Subsequently, colony-simulating activity in various conditioned media was assayed using light-density (less than 1.070 g/ml), nonadherent normal human marrow cells. Live monocyte-macrophages synergized with and significantly (P less than 0.01) agumented the T lymphocyte-derived colony-stimulating activity elaboration; while killed monocytes-macrophages had no such effect. Similarly, actinomycin D and cycloheximide not only diminished monocyte-macrophage colony-stimulating activity elaboration but also reduced their synergistic interaction with T lymphocytes and their ability to augment the T lymphocyte-derived colony-stimulating activity elaboration. In contrast, mitomycin C failed to diminish both - monocyte-macrophages' ability to synergise with T lymphocytes and also to augment T lymphocyte-derived colony-stimulating activity. These data suggest that monocyte-macrophages require an intact transcriptional and translational processes, but not DNA synthesis for synergising with T lymphocytes or for augmenting T lymphocyte colony-stimulating activity elaboration.

The mechanism of lithium carbonate-induced augmentation of colony-stimulating activity elaboration in man

Lithium carbonate (Li) has been reported to elevate granulocyte counts in patients with certain neutropenic disorders and to improve chemotherapy-induced granulocytopenia. To investigate the mechanisms involved in the increase in myelopoiesis, the effect of Li on monocytemacrophage (M phi)- and T-lymphocyte (TL)-derived colony-stimulating activity (CSA) were studied in vitro. Li induced a dose-related increase in both M phi- and TL-derived CSA over that in non-Li-stimulated cell populations. However, the increase was significant (p less than 0.007) only at a higher concentration of Li (2 mEq/l). The results of co-incubating TL with M phi with or without Li indicated that Li significantly enhanced synergistic CSA production by the two cell populations (p less than 0.02). We further demonstrated the presence of a larger proportion of M phi with TL rosettes in the presence of Li (62%) than in its absence (21%). Further experiments with concanavalin A (Con-A)-inducible suppressor TL suggested that Li effectively blocks the suppressor TL-mediated suppression of CSA. These data suggest that Li enhances M phi and TL interaction which results in an augmented CSA elaboration. Further, Li would be more effective in those neutropenic disorders associated with enhanced suppressor TL activity. For an optimal effect, however, Li would require appropriately functioning M phi and non-suppressor subsets of TL and an intact stem cell pool.

T lymphocytes involved in inhibition of granulopoiesis in two neutropenic patients are of the cytotoxic/suppressor (T3+T8+) subset

T lymphocyte-mediated bone marrow failure is a recently recognized clinical disorder, but the T lymphocyte subsets responsible for mediating the inhibitory effect have not been identified. We obtained T lymphocytes from the bone marrow of two patients with T lymphocyte-mediated granulopoietic failure, exposed them to monoclonal antibodies (OKT3, OKT4, and OKT8) in cytotoxicity assays, then recombined the treated T cells with autologous T-depleted marrow cells in clonal assays for granulocyte/macrophage progenitors (CFU-GM). Treatment of T cells with OKT3 and OKT8 abrogated their granulopoietic inhibitory effect but treatment with OKT4 did not. Therefore, in these two patients, the lymphocytes that played a role in the inhibition of granulopoiesis were of the cytotoxic/suppressor subset.

Interaction of lactoferrin, monocytes, and T lymphocyte subsets in the regulation of steady-state granulopoiesis in vitro

Colony-stimulating activities (CSA) are potent granulopoietic stimulators in vitro. Using clonogenic assay techniques, we analyzed the degree to which mononuclear phagocytes and T lymphocytes cooperate in the positive (production/release of CSA) and feedback (inhibition of CSA production/release) regulation of granulopoiesis. We measured the effect of lactoferrin (a putative feedback regulator of CSA production) on CSA provision in three separate assay systems wherein granulocyte colony growth of marrow cells from 22 normal volunteers was stimulated by (a) endogenous CSA-producing cells in the marrow cells suspension, (b) autologous peripheral blood leukocytes in feeder layers, and (c) medium conditioned by peripheral blood leukocytes. The CSA-producing cell populations in each assay were varied by using cell separation techniques and exposure of isolated T lymphocytes to methylprednisolone or to monoclonal antibodies to surface antigens and complement. We noted that net CSA production increased more than twofold when a small number of unstimulated T lymphocytes were added to monocyte cultures. Lactoferrin's inhibitory effect was also T lymphocyte dependent. The T lymphocytes that interact with monocytes and lactoferrin to inhibit CSA production are similar to those that augment CSA production because their activities are neither genetically restricted not glucocorticoid sensitive, and both populations express HLA-DR (Ia-like) and T3 antigens but not T4 or T8 antigens. These findings are consistent with results of our studies on the mechanism of lactoferrin's inhibitory effect with indicate that mononuclear phagocytes produce both CSA and soluble factors that stimulate T lymphocytes to produce CSA, and that lactoferrin does not suppress monocyte CSA production, but does completely suppress production or release by monocytes of those factors that stimulate T lymphocytes to produce CSA. We conclude that mononuclear phagocytes and a subset of T lymphocytes exhibit important complex interactions in the regulation of granulopoiesis.

Histamine production during the anti-allograft response. Demonstration of a new lymphokine enhancing histamine synthesis

Histamine production is greatly increased during culture of allograft recipient spleen cells in the presence of immunizing cells (secondary mixed leukocyte cultures [MLC]) as compared to that found in primary MLC (i.e., without previous allograft). This phenomenon appears after 24 h of culture and reaches its maximum at 48 h. Optimal increased histamine production is observed when MLC is performed with spleen cells removed from mice during rejection. This increased production of histamine during secondary MLC results from the action of a lymphokine: the histamine-producing cell stimulating factor (HCSF). This factor is released by T lymphocytes. Its production requires specific stimulation of the recipient lymphocytes because increase in histamine production during secondary MLC can be only observed when recipient cells are cultured with stimulating cells bearing at least one homology at K or D loci with immunizing cells. HCSF acts on a cell which is present in bone marrow, spleen, blood, and peritoneal cells but absent in thymus or lymph node cells. This target cell is found in the less-dense layer of a discontinuous Ficoll-gradient of bone marrow cells. HCSF is heat stable, destroyed by trypsin treatment, and has a molecular weight between 50,000 and 100,000. It acts on its target cells by increasing histidine decarboxylase activity.

Monoclonal antibody assessments of T cell interactions in erythropoietin studies

The contemporary application of clonal assay techniques has greatly expanded our knowledge of the regulation of hematopoiesis. Our efforts have been directed toward the investigation of non-erythropoietin-mediated regulation of human erythropoiesis in the form of cell-to-cell interaction between mature T cells and erythroid progenitors. Our data indicate that three such progenitors, the early marrow erythrocyte precursor BFU-E, the more mature marrow erythrocyte precursor, CFU-E and the peripheral blood BFU-E, each exhibit totally different requirements for their colony expression in culture, with respect to the absence of erythropoietin and the presence of mature T cells or their products. The capacity of erythroid progenitors to withstand incubation in the absence of erythropoietin appears to be a characteristic of immature rather than mature erythroid progenitors. Furthermore, use of OKT3 antibody depletion techniques shows that peripheral blood-derived BFU-E appear to depend upon mature lymphocytes or T cell-conditioned medium for erythropoietin-stimulated differentiation while bone marrow BFU-E and CFU-E have no requirement for mature T cells to produce erythropoietin-dependent maturation. Our results, plus a vast array of data provided by other investigators in the field, are integrated into a proposed framework for further investigation of T cell induction of erythropoietin-dependent erythroid differentiation aimed at more specifically identifying the inducer cell subset(s) in that system.

Growth and differentiation in vitro of mast cells from mesenteric lymph nodes of Nippostrongylus brasiliensis-infected rats

Intestinal mastocytosis begins to develop in rats, depending on the strain, at 14 (outbred Sprague-Dawley, SD) or 16 (inbred Lewis, L) days after infection with the nematode Nippostrongylus brasiliensis (Nippo). We have investigated in vitro mastopoiesis from mesenteric lymph node (MLN) cells cultured at various intervals post-infection, using a modified Marbrook liquid system. Greater increases in mast cells (MC) were observed in cultures of SD-MLN removed on day 14 after Nippo infection (IMLN-14) than from MLN removed from uninfected animals (NMLN): seven- to twenty-fold versus up to two-fold at 2 weeks and forty- to two hundred-fold versus up to twenty-fold at 4 weeks, respectively (P < 0.002). In contrast, similar differential increases in MC and histamine compared to uninfected controls, were demonstrated in 2 week cultures of MLN from L strain rats removed 17 (IMLN-17) and 20 (IMLN-20) but not 14 days after Nippo infection (P < 0.001). the presence of phytohaemagglutinin (PHA) in vitro was associated with enhanced MC differentiation from both IMLN-17 and IMLN-20, while worm antigen (Ag) stimulated mastopoiesis from IMLN-17, but suppressed the response from IMLN-20 (P < 0.02). Conditioned media (CM) prepared from unstimulated or PHA-stimulated IMLN-32 (i.e. removed 32 days after Nippo infection) caused significant mastopoiesis from NMLN in vitro when compared to no CM or Ag-stimulated CM (P < 0.01). Either MC precursors or cells which help MC differentiation exist in increased numbers in MLN of Nippo-infected rats. Mitogenic or antigenic stimulation modulates in vitro mastopoiesis, either directly or through soluble factors derivable from MLN cells. These in vitro methods can be utilized to understand further mechanisms of intestinal mastocytosis in the rat.

X-ray-induced production of granulocyte-macrophage colony-stimulating factor (GM-CSF) by mouse spleen cells in culture

Spleen cells were collected from normal mice and cultured in a medium containing 20% calf serum. Addition of lipopolysaccharide (LPS) in the culture significantly increased the production of granulocyte-macrophage colony-stimulating factor (GM-CSF), and a maximum induction was attained in 5 days. Irradiation of the spleen cells with 300 to 3,000R X-rays also enhanced the production of GM-CSF, but there was a latent period of about 5 days before the factor appeared in the culture medium. The observed difference between LPS and X-rays in the timing of inducing GM-CSF production in the spleen cell culture was consistent with the difference in timing of the increase of spleen cell proliferation observed in animals after the administration of LPS or during recovery from damages by X-irradiation. It was observed furthermore that the X-ray-induced GM-CSF differed from the LPS-induced GM-CSF in its molecular properties; the X-ray-induced factor was represented by an acidic (pI = 3.0) 70,000-dalton species, while the LPS-induced factor was much smaller in size (M.W. 20,000) and less acidic (pI = 5.4). These results suggest that different mechanisms of GM-CSF production operate in the spleen in response to either LPS or X-rays.

The role of eosinophils in granulopoiesis. I. Eosinophilia in neutropenic patients

The role of eosinophils in granulopoiesis is unclear. In a variety of conditions, the level of eosinophils is inversely related to the level of neutrophils. The present report describes two patients with eosinophilia and neutropenia and examines the in vitro effects of eosinophils on the colony formation of their bone marrow in semisolid culture medium. The addition of autologous eosinophils to bone marrow cultures from these patients resulted in a decrease in the number of colonies; in contrast, antieosinophilic serum increased the number of colony-forming units. Indomethacin, an inhibitor of prostaglandin, was capable of reversing the effects of added eosinophils. The findings suggest that eosinophils have an inhibitory effect on in vitro granulopoiesis. The suppressive effects may be due to the high content of prostaglandin E found in eosinophils. A schematic diagram based on the current knowledge of the mechanism of granulopoiesis is presented.

Basophil production

Factors influencing basophil production from the bone marrow of ovalbumin (OA)-sensitized guinea pigs have been examined in vitro. Autologous co-cultures of marrow and spleen cells from OA-immune animals contained significantly higher numbers of basophils after 7 d of liquid culture in the presence of OA, compared with control co-cultures or with marrow cultures alone (P < 0.005). Basophils increased in co-culture as the number of spleen cells added to a fixed number of marrow cells was increased from 0.10 to 2.5 x 10(6)/ml; at each spleen cell concentration, the presence of OA significantly enhanced basophil production in vitro when compared with unstimulated co-cultures. There was no basophil production from spleen cell suspensions cultured in the absence of autologous marrow cells. Conditioned media (CM) prepared from OA-stimulated spleen cells of OA-treated animals (CM-OA) caused a specific stimulation of basophil production from normal guinea pig bone marrow cells in liquid cultures (P < 0.01). Phytohemagglutinin (PHA)- and pokeweed mitogen-stimulated CM (CM-PHA, CM-pokeweed mitogen) nonspecifically enhanced normal basophilopoiesis, causing dose-dependent increases in basophils and histamine in vitro. CM-OA and CM-PHA also preferentially stimulated formation of neutrophil-macrophage colony-forming units in semisolid methylcellulose cultures.CM-PHA prepared from T cell-enriched splenic cell suspensions contained basophil-stimulating activity, whereas T cell-depleted CM-PHA activity did not exceed control values (P < 0.01). Preliminary characterization of CM-PHA revealed that basophil-stimulating activity was predominantly heat stable and nondialyzable. These results demonstrate OA-specific, as well as mitogen-dependent T-cell regulation of guinea pig basophilopoiesis in vitro. The data are compatible with the existence of a specific "basophilopoietin" in CM derived from guinea pig splenic T cells.

Properties and separation of T lymphocyte growth stimulatory activity (TL-GSA) and of granulocyte-macrophage colony stimulatory activity (GM-CSA) produced separately from two human T lymphocyte subpopulations

We have previously identified two stimulatory activities affecting blood cell maturation in PHA-stimulated human lymphocytes conditioned medium (PHA-LyCM). One was granulocyte-macrophage colony stimulatory activity (GM-CSA), and the other was T lymphocyte growth stimulatory activity (TL-GSA) in suspension culture. In this paper we have shown that although both activities can be produced from purified non-adherent human T lymphocytes, they are produced from two distinct subpopulations. The production of these activities was greatly enhanced by T cell mitogens. Both protein factors were relatively heat stable (56 degrees, 30 minutes), were sensitive to trypsin treatment and were specific for primate blood cells. These two activities were fractionated by means of ammonium sulfate precipitation, Sephadex G-150 gel filtration, DEAE cellulose and Con A-Sepharose column chromatographies. MW of the major peak estimated from the elution volume of gel filtration in the presence of 0.5 M NaCl was 40,000 for GM-CSA and 13,000 for TL-GSA. Results from Con A-Sepharose column showed that while about 70% of TL-GSA was bound to Con A, less than 25% of GM-CSA was bound. These observations show that the majority of TL-GSA and GM-CSA were separable by these two conventional column chromatographic methods.

Neutropenia in three patients with rheumatic disorders. Suppression of granulopoiesis by control-sensitive thymus-dependent lymphocytes

A man with polymyalgia rheumatica (patient 1) and two patients (2 and 3) with Felty's syndrome had neutropenia at the time of diagnosis. Bone marrow samples in each patient were cellular but showed an "arrest" of granulocyte maturation at the myelocyte stage. Agar colony growth of marrow cells from each patient was subnormal but increased after removal of sheep erythrocytes rosette-forming cells (thymus-dependent [T] cells) from marrow cell suspensions before culture. Preincubation of marrow cells with cortisol also enhanced colony growth. Maximum enhancement with cortisol occurred at 1 mM (patient 1), 1 microM (patient 2), and 10 nM (patient 3). Cortisol failed to enhance colony growth after removal of T cells from marrow cell suspensions. Peripheral blood lymphocytes (PBL) and PBL-conditioned medium from all three patients inhibited colony growth of normal human marrow cells. Cortisol treatment of PBL or T depletion from PBL abrogated the inhibition in coculture and with conditioned medium. Prednisone therapy resulted in the disappearance of suppressor T-cell function concomitant with hematologic improvement in patients 2 and 3, but suppressor T cells persisted in patient 1, who did not respond to prednisone. We conclude that cortisol-sensitive T lymphocytes inhibited granulopoiesis in vitro probably by elaboration of a soluble factor or factors. Our results suggest (a) that neutropenia in these patients resulted, at least in part, from T-cell suppression of granulopoiesis, (b) that the effectiveness of prednisone therapy was a result of its inhibition of suppressor T cells, and (c) that responses to glucocorticoid therapy may be predicted in such patients with the agar culture technique and cortisol dose response in vitro.

Control factors of granulopoiesis in human serum

The role of serum factors in the modulation of production of colony-stimulating activity (CSA) has been investigated. A factor has been described, and partially characterized, in human serum that has the capacity to stimulate increased synthesis and release of CSA by human mononuclear cells (MNC). MNC RNA and protein synthesis are required to demonstrate this effect of serum, but DNA synthesis and mitotic division are not required. The factor in serum resulting in this effect is a heat-labile protein with a molecular weight slightly greater than that of CSA.

Splenomegaly, enhanced phagocytosis, and anemia are thymus-dependent responses to malaria

Immunologically competent mice and mice with defined immunological deficiencies were infected with Plasmodium yoelii. Splenomegaly, enhanced phagocytosis, and anemia were most marked in infected mice having intact thymic tissue. Whereas the spleens of infected nude mice increased minimally in size, the relative blood hemoglobin levels and the rates of carbon clearance in these mice were similar to those of noninfected, immunologically intact mice. Thymus-reconstituted nude mice and B-cell-deficient mice responded to infection in a manner similar to that of infected immunocompetent mice. These data demonstrate that the hallmarks of malaria, i.e., splenomegaly, enhanced phagocytosis, and anemia, are thymus-dependent responses to infection.

The polyclonal B cell activator dextran-sulphate induces formation of colony stimulating activity

The effect of dextran-sulphate (DS), a polyclonal activator known to stimulate immature murine B-cells, was assayed in a culture system allowing the growth of myeloid cells. It was known that DS induced the production of a myeloid colony stimulating factor (CSF) by cells from both spleen and bone marrow. Nylonwool purified mouse spleen cells, enriched for T cells, showed a dimished CSF production in response to DS, while CSF production in response to Con A was increased. Furthermore, DS induced CSF in both spleen and bone marrow cells from nude mice. Removal of macrophages did not affect CSF production. The CSF induced was non-dialysable and no small molecular weight or lipoprotein inhibitors could be demonstrated. The results suggest that DS activates cells other than T cells or macrophages (possibly B cells or null cells) to produce a myeloid stem cell stimulating substance. These results indicate that interactions between lymphoid and myeloid cells can take place during differentiation.

Human erythroid burst-forming unit: T-cell requirement for proliferation in vitro

Human mononuclear leukocytes were fractionated into populations of null, T and B cells by immunoabsorbent column chromatography followed by E-rosette formation and purification of T cells by differential centrifugation and osmotic lysis. The unfractionated and fractionated cell populations were first separately cultured for 14 days in plasma clots in the presence of two international units erythropoietin. Typical erythroid burst-forming unit (BFU-E)-derived colonies grew in the unfractionated cell cultures but not from T- or B-cell cultures. BFU-E colonies grew in null cell cultures but most of the colonies were small and variably hemoglobinized with less than three subcolonies. When intact T cells were added to null cells and cocultured, many typical large BFU-E colonies with more than 10 well homogenized subcolonies appeared. Increasing numbers of large BFU-E colonies in null cell cultures were induced by stepwise addition of T cells but not by the addition of B cells. A conditioned medium in which T cells had been induced to divide by tetanus toxoid substituted for intact T cells in this T-cell-dependent BFU-E colony formation observed in null cells. These findings demonstrate that the BFU-E, a committeded erythroid stem cell, resides in the null cell fraction of peripheral blood, but its proliferative capacity and differentiation in vitro requires a soluble product of T cells. Such experiments now permit a new approach to the assessment of various disorders of erythropoiesis. Erythroid hypoplasia in a particular case may be due to dysfunction of the committed precursor cell or to a failure of a helper effect induced by T cells.

Immune suppression of hematopoiesis

Recent evidence suggests that immune mechanisms can injure proliferating hematopoietic precursor cells in the bone marrow. These may involve either humoral antibody or cell-mediated cytotoxic mechanisms. Immune injury can result in a variety of bone marrow failure syndromes. Immunologically induced abnormalities or blood cell production may be restricted to a single series, such as erythrocyte or granulocyte precursors, or may involve several hematopoietic lines; clinical manifestations reflect the cell line or lines that are injured. Immune suppression of hematopoiesis has now been described in pure red cell aplasia, immune panleukopenia, systemic lupus erythematosus, atypical cases of aplastic anemia and miscellaneous other hematologic diseases.

Bacterial, serum and cellular modulation of granulopoietic activity

The interaction human peripheral blood lymphocytes, monocytes, gram-positive bacteria and human serum in the release of colony stimulating activity (CSA) has been studied. CSA was assayed by the soft agar technique using human and murine bone marrow cells. It has been demonstrated that gram-positive organisms and their products can stimulate release of CSA by mononuclear cells. Human serum is also effective in promoting release of CSA. Release is further modulated by interactions between lymphocytes and monocytes, and lymphocytes may serve to control the modulation. The serum component is sensitive to temperature inactivation suggesting that it may have a specific physiologic role in regulation. Bacterial products, on the other hand, are not subject to temperature inactivation and require the presence of human serum for activity to be expressed.