Toll-like receptor-induced expression of epithelial cytokine receptors on haemopoietic progenitors is altered in allergic asthma.

BACKGROUND: Haemopoietic progenitor cells (HPC) migrate to sites of allergic inflammation where, upon stimulation with epithelial cytokines, they produce Th2 cytokines and differentiate into mature eosinophils and basophils. They also express Toll-like receptors (TLR) involved in antimicrobial responses. OBJECTIVE: The objective of this study was to compare TLR expression on peripheral blood HPC and TLR-induced responses, in particular changes in epithelial cytokine receptors, in healthy and asthmatic subjects at baseline and following allergen challenge. METHODS: Ten healthy and 11 allergic asthmatic subjects were studied. HPC-enriched cell populations were stimulated with TLR-2, TLR-4 or TLR-9 ligands. TLR expression by circulating HPC and interleukin (IL)-25 (IL-17RB), IL-33 (ST2) and thymic stromal lymphopoietin receptor (TSLPR) expression after TLR ligation were examined by flow cytometry at baseline and, in asthmatics, following allergen challenge. The effects of dexamethasone (Dex) on TLR-induced responses were also assessed. RESULTS: Asthmatics had significantly lower circulating HPC expressing TLR-2 and TLR-9 with a similar trend for TLR-4. TLR-4 stimulation of HPC yielded higher numbers of TSLPR+ cells in asthmatics compared with healthy subjects. A similar trend was seen for TLR-9 ligation, an effect further augmented by allergen inhalation. Allergen challenge also enhanced TLR-induced ST2 expression on HPC. Treatment with Dex in vitro increased TLR-4-induced TSLPR expression but had no effect on other epithelial cytokine receptors. CONCLUSIONS AND CLINICAL RELEVANCE: These data demonstrate an interaction between allergen and TLR ligand exposure in asthmatics. Allergen inhalation augments the TLR-induced inflammatory response by HPC, possibly leading to increased "in situ haemopoiesis" through up-regulation of TSLPR. These findings show that HPC may be a part of the pro-inflammatory cascade in pathogen-induced asthma exacerbation through their increased responsiveness to TLR stimulation.

T regulatory cell phenotypes in peripheral blood and bronchoalveolar lavage from non-asthmatic and asthmatic subjects.

BACKGROUND: An unresolved issue in T regulatory cells' cell biology is the lack of consensus on phenotypic markers that accurately define the natural Treg (nTreg) population. OBJECTIVES: To examine nTreg frequency and functional capacity in healthy controls and their frequency in asthmatic subjects using three different phenotypic strategies. We hypothesized that phenotypically different nTreg are quantitatively and functionally different. METHODS: Thirty-four healthy, non-asthmatic and 17 asthmatic subjects were studied. Three nTreg phenotypes were defined as follows: nTreg1 (CD4(+) CD25(+) Foxp3(+) ), nTreg2 (CD4(+) CD25(+) CD127(low) Foxp3(+) ), and nTreg3 (CD4(+) CD25(high) Foxp3(+) ). The flow cytometric determination of nTreg frequency in peripheral blood (PB) and bronchoalveolar lavage (BAL) was performed using fluorescently labelled antibodies. Peripheral blood nTreg functional capacity was assessed using a CFSE-based suppression assay. RESULTS: There was a significantly lower frequency of PB nTreg3 compared to nTreg2 and nTreg1 (P < 0.05). Both nTreg2 and nTreg3 had a significantly greater suppressive capacity than nTreg1 at T responder (Tresp) to nTreg ratios of 16 : 1 up to 1 : 1 (P < 0.01). Asthmatics exhibited a significantly lower PB nTreg3 and nTreg1 frequency than healthy controls (P < 0.05). There were no differences between healthy controls and asthmatic subjects when comparing BAL nTreg frequency. CONCLUSIONS AND CLINICAL RELEVANCE: Phenotypically different nTreg subsets are quantitatively and functionally different and are variably observed in asthma. The CD4(+) CD25(high) Foxp3(+) phenotype was the least frequent, but demonstrated the greatest suppression, and was significantly lower in PB of asthmatic subjects. Consequently, it is imperative that nTreg phenotypes be clearly defined and that the interpretation of their frequency and function be phenotype specific.

The Canadian healthy infant longitudinal development birth cohort study: biological samples and biobanking.

BACKGROUND: It is hypothesised that complex interactions between genetic and environmental factors give rise to allergy and asthma in childhood. The Canadian Healthy Infant Longitudinal Development (CHILD) study was designed to explore these factors. METHODS: CHILD is a longitudinal, general population birth cohort study following infants from mid-pregnancy to age 5 years. Over this time period, biological samples, questionnaires, clinical measures and environmental data are collected. RESULTS: A total of 3624 families have been recruited, and many thousands of samples and questionnaires have been collected, annotated, and archived. This report outlines the rationale and methodology for collecting and storing diverse biological samples from parents and children in this study, and the mechanisms for their release for analyses. CONCLUSIONS: The CHILD sample and data repository is a tremendous current and future resource and will provide a wealth of information not only informing studies of asthma and allergy, but also potentially in many other aspects of health relevant for Canadian infants and children.

T cell-mediated induction of thymic stromal lymphopoietin in differentiated human primary bronchial epithelial cells.

BACKGROUND: Inhaled peptide challenge has been shown to induce T cell-mediated, isolated late asthmatic reaction (LAR), characterized by recruitment of CD4(+) T cells and increased levels of thymus and activation-regulated chemokine (TARC; CCL17). Epithelial-derived thymic stromal lymphopoietin (TSLP) has been shown to modulate dendritic cell function to promote TH 2 responses via CCL17 production. OBJECTIVES: To elucidate the mechanisms involved in allergen-specific T cell-induced LAR and recruitment of CD4(+) T cells by examining the effects of T cell-derived factors on the induction of TSLP in primary bronchial epithelial cells (PBEC). METHODS: PBEC grown at air-liquid interface from healthy individuals and patients with asthma were stimulated with double-stranded RNA (dsRNA) or supernatants from activated allergen-specific T cells. TSLP was measured in PBEC culture supernatants. Neutralizing antibodies and signalling inhibitors were used to examine the mechanisms responsible for the induction of epithelial-derived TSLP. The functional activity of PBEC-derived TSLP was measured using a bioassay involving the induction of CCL17 production from monocyte-derived dendritic cells (moDC). RESULTS: Both dsRNA and allergen-specific T cells induced enhanced TSLP secretion from asthmatic PBEC compared to healthy PBEC. Activated PBEC culture supernatant induced TSLP-dependent CCL17 production from moDC in a manner related to clinical asthmatic status. IL-1ß, IL-6, and CXCL8, rather than TH 2 cytokines (IL-4/5/13), appeared to be the principle mediators of allergen-specific T cell-dependent induction of epithelial-derived TSLP, which was regulated by the MEK, MAPK, and NFκB pathways. CONCLUSION AND CLINICAL RELEVANCE: Our data reveal a novel effect of allergen-specific T cells as a positive regulator of TSLP production by epithelial cells, suggesting T cell-airway epithelium interactions that may lead to maintenance and amplification of allergic inflammation. TSLP is currently a candidate for therapeutic intervention in asthma, but the factors that drive TSLP expression (T cell-derived factors) may be equally relevant in the treatment of allergic inflammation.

Anti-cyclic citrullinated peptide antibody as a marker of erosive arthritis in patients with systemic lupus erythematosus: a systematic review and meta-analysis.

OBJECTIVE: Anti-cyclic citrullinated peptide (CCP) antibody is an established marker in the diagnosis and prognostication of rheumatoid arthritis (RA). Infrequently, systemic lupus erythematosus (SLE) patients also develop a deforming erosive arthritis, similar to that of RA. Our objective was to determine whether anti-CCP antibody is a useful marker of erosive disease in SLE patients presenting with arthritis. METHODS: Electronic databases EMBASE, MEDLINE and non-indexed MEDLINE citations were searched through April 11, 2014, using the outlined key terms. Studies meeting predefined inclusion and exclusion criteria were reviewed. Two reviewers independently assessed the quality of included articles using previously described criteria. The DerSimonian-Laird random effects model was used to calculate pooled sensitivity and specificity of anti-CCP antibody for erosive arthritis in SLE. RESULTS: Seven articles met inclusion and exclusion criteria. A total of 609 SLE patients with arthritis were identified, 70 of whom had erosive disease. Pooled sensitivity and specificity of anti-CCP antibody for erosive arthritis was 47.8% (95% CI, 26.2%-70.2%) and 91.8% (95% CI, 78.4%-97.2%), respectively. CONCLUSION: Our findings suggest that anti-CCP antibody is a highly specific marker for erosive arthritis in SLE. Longitudinal prospective studies are needed to determine if anti-CCP antibody can be used as a predictor of erosive disease.

The LINA cohort: indoor chemical exposure, circulating eosinophil/basophil (Eo/B) progenitors and early life skin manifestations.

BACKGROUND: Hematopoietic progenitor cells, especially those committed to the Eo/B lineage, are known to contribute to allergic inflammation. OBJECTIVE: The aim of the present study was to investigate whether environmental factors are associated with changes in numbers of circulating Eo/B progenitors at 1 year of age. METHODS: Peripheral blood from 60 1-year-old children enrolled in the LINA (Lifestyle and environmental factors and their Influence on Newborns Allergy risk) birth cohort was assessed for Eo/B progenitor cells (Eo/B CFU) using standardized and validated methylcellulose assays. Frozen peripheral blood mononuclear cells (PBMC) were cultured in the presence of IL-3, IL-5 or GM-CSF, and Eo/B CFUs enumerated. Clinical outcomes and exposure to environmental tobacco smoke (ETS) were documented by standardized questionnaires, and indoor volatile organic compound (VOC) concentrations were assessed by passive sampling. RESULTS: Children with skin manifestations (atopic dermatitis or cradle cap) within the first year of life had higher numbers of circulating IL-3-, IL-5- or GM-CSF-stimulated Eo/B CFUs (P < 0.05) at 1 year. In children with cradle cap, a positive correlation was found between Eo/B CFUs and exposure to ETS-related VOCs during pregnancy or at 1 year of age (P < 0.05). CONCLUSIONS AND CLINICAL RELEVANCE: This is the first demonstration that environmental exposures are positively associated with levels of circulating Eo/B progenitors. The recruitment and differentiation of Eo/B progenitors in response to environmental triggers may play a role in the development of skin manifestations during the first year of life.

Haemopoietic processes in allergic disease: eosinophil/basophil development.

Haemopoietic myeloid progenitors contribute to the ongoing recruitment of pro-inflammatory cells, such as eosinophils and basophils (Eo/B), to target tissue sites in allergic diseases. It is apparent that the development of allergic inflammation is critically dependent on the ability of the bone marrow to support the proliferation, differentiation and mobilization of haemopoietic progenitors. The haemopoietic inductive microenvironment in the bone marrow is crucial for providing signals necessary for maintenance of progenitor populations at varying stages of lineage commitment and permitting these cells to circulate in the bloodstream. Progenitors demonstrate responsiveness to specific cytokines, which varies with stage of differentiation. Pro-inflammatory signals, Th2 cytokines in particular, generated following allergen challenge, can impact on haemopoietic progenitor differentiation and mobilization, leading to accelerated Eo/B production. Allergen inhalation by allergic asthmatics induces a time-dependent change in cytokine levels within the bone marrow compartment, influencing differentiation of Eo/B progenitors, as evidenced by the relationship between increased bone marrow IL-5 levels and Eo/B production. It is proposed that inhaled allergen induces trafficking of IL-5-producing T lymphocytes to the bone marrow, further promoting eosinophilopoiesis through IL-5R signalling. In this manner, Th2 lymphocyte trafficking from the airway may regulate events occurring in the bone marrow. Negative regulators of Eo/B differentiation, including Th1 cytokines, may prove to be important for restoring homeostasis. Eo/B progenitors are also altered in cord blood of infants at risk of atopy and asthma, offering a potential biomarker for, and raising the possibility that Eo/B progenitors are directly involved in the development of allergic disease. For example, changes in the expression of haemopoietic cytokine receptors on cord blood progenitor cells are associated with maternal allergic sensitization, atopic risk and its development, suggesting that haemopoietic processes underlying the allergic phenotype may begin to evolve in the perinatal period.

A multifunctional cell surface developmental stage-specific antigen in the cockroach embryo: involvement in pathfinding by CNS pioneer axons.

mAb DSS-8 binds to a 164-kD developmental stage-specific cell surface antigen in the nervous system of the cockroach, Periplaneta americana. The antigen is localized to different subsets of cells at various stages of development. The spatial and temporal distributions of DSS-8 binding were determined and are consistent with this antigen playing multiple roles in the development of the nervous system. Direct identification of some of these functions was made by perturbation experiments in which pioneer axon growth occurs in embryos that are cultured in vitro in the presence of mAb DSS-8 or its Fab fragment. Under these conditions the pioneer axons of the median fiber tract grow but follow altered pathways. In a smaller percentage of the ganglia, the immunoreagents additionally produce defasciculation of a subset of DSS-8 labeled axons. Therefore, direct roles for the DSS-8 antigen in both the guidance of pioneer axons and selective fasciculation have been demonstrated.

A role for proteoglycans in the guidance of a subset of pioneer axons in cultured embryos of the cockroach.

Several molecules involved in the development of the nervous system have specific binding sites for the glycosaminoglycan (GAG) side chains of proteoglycans. Exogenous GAGs should bind to these sites, competitively inhibit interactions with proteoglycans, and perturb development. GAGs added to the culture medium perturb the in situ growth of pioneer axons in cultured cockroach embryos by producing axon defasciculation and growth in incorrect directions. The specificity of this phenomenon is evident from the following observations: Of all the GAGs tested only heparin and heparan sulfate produced perturbation; of the six axon tracts being pioneered during the culture period only two of them are perturbed by the GAGs; and similar perturbations are produced when embryos are cultured in the presence of heparinase II and heparitinase.

Allergic rhinitis management pocket reference 2008.

Allergic rhinitis is a major chronic respiratory disease because of its prevalence, impacts on quality of life and work/school performance, economic burden, and links with asthma. Family doctors (also known as 'primary care physicians' or 'general practitioners') play a major role in the management of allergic rhinitis as they make the diagnosis, start the treatment, give the relevant information, and monitor most of the patients. Disease management that follows evidence-based practice guidelines yields better patient results, but such guidelines are often complicated and may recommend the use of resources not available in the family practice setting. A joint expert panel of the World Organization of Family Doctors (Wonca), the International Primary Care Airways Group (IPAG) and the International Primary Care Respiratory Group (IPCRG), offers support to family doctors worldwide by distilling the globally accepted, evidence-based recommendations from the Allergic Rhinitis and its Impact on Asthma (ARIA) initiative into this brief reference guide. This guide provides tools intended to supplement a thorough history taking and the clinician's professional judgment in order to provide the best possible care for patients with allergic rhinitis. A diagnostic Questionnaire specifically focuses the physician's attention on key symptoms and markers of the disease. When questionnaire responses suggest a diagnosis of allergic rhinitis, a Diagnosis Guide and a simple flowchart then lead the clinician through a series of investigations commonly available in primary care to support the diagnosis. In addition, key aspects of differential diagnosis are illuminated. According to ARIA, allergic rhinitis may be classified as Intermittent or Persistent, and as Mild or Moderate/Severe. The classification of rhinitis determines the treatment necessary, as set out in an ARIA flowchart included in this guide. The guide also includes information about the strength of evidence for efficacy of certain rhinitis treatments, a brief discussion of pediatric aspects, and a glossary of allergic rhinitis medications to assist the clinician in making medication choices for each individual patient. Finally, many patients with allergic rhinitis also have concomitant asthma, and this must be checked. The World Organization of Family Doctors has been delegated by WHO as the group that will be taking primary responsibility for education about chronic respiratory diseases among primary care physicians globally. This document will be a major resource in this educational program.

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.

Allergen-induced increases in IL-5 receptor alpha-subunit expression on bone marrow-derived CD34+ cells from asthmatic subjects. A novel marker of progenitor cell commitment towards eosinophilic differentiation.

We have proposed previously that hemopoietic myeloid progenitors contribute to the ongoing recruitment of proinflammatory cells, namely eosinophils, to sites of allergen challenge in allergic diseases such as asthma. In this study, we investigated the involvement of bone marrow-derived progenitors in the development of allergen-induced pulmonary inflammation in mild asthmatic subjects. By flow cytometry, we enumerated the level of expression of CD34, a hemopoietic progenitor cell marker, on bone marrow aspirates taken before and 24 h after allergen challenge. In addition, the coexpression of the alpha-subunits of IL-3 receptor (IL-3R) and IL-5 receptor (IL-5R) on CD34+ cells was investigated. After allergen-challenge, although no significant change in total BM CD34+ cell numbers was observed, a significant increase in the proportion of CD34+ cells expressing IL-5R alpha, but not IL-3R alpha, was detected in the 24-h post-allergen, compared with the pre-allergen bone marrow. This was associated with a significant blood and sputum eosinophilia and increased methacholine airway responsiveness, 24 h post-allergen. Using simultaneous in situ hybridization and immunocytochemistry, we colocalized the expression of messenger RNA for membrane-bound IL-5R alpha to CD34+ cells. In summary, our data suggest that increased expression of IL-5R alpha on CD34+ cells favors eosinophilopoiesis and may thus contribute to the subsequent development of blood and tissue eosinophilia, a hallmark of allergic inflammation.

Eosinophils in chronically inflamed human upper airway tissues express transforming growth factor beta 1 gene (TGF beta 1).

Transforming growth factor beta (TGF beta) is a multifunctional protein which has been suggested to play a central role in the pathogenesis of chronic inflammation and fibrosis. Nasal polyposis is a condition affecting the upper airways characterized by the presence of chronic inflammation and varying degrees of fibrosis. To examine the potential role of TGF beta in the pathogenesis of this condition, we investigated gene expression and cytokine production in nasal polyp tissues as well as in the normal nasal mucosa. By Northern blot analysis using a porcine TGF beta 1 cDNA probe, we detected TGF beta 1-specific mRNA in nasal polyp tissues, as well as in the tissue from a patient with allergic rhinitis, but not in the normal nasal mucosa. By the combination of tissue section staining with chromotrope 2R with in situ hybridization using the same TGF beta 1 probe, we found that approximately 50% of the eosinophils infiltrating the polyp tissue express the TGF beta 1 gene. In addition, immunohistochemical localization of TGF beta 1 was detected associated with extracellular matrix as well as in cells in the stroma. These results suggest that in nasal polyposis where eosinophils are the most prevalent inflammatory cell, TGF beta 1 synthesized by these cells may contribute to the structural abnormalities such as stromal fibrosis and basement membrane thickening which characterize this disease.

Systemic aspects of allergic disease: the role of the bone marrow.

In recent years, there has been an increasing appreciation of the important contribution of bone-marrow-related, hemopoietic mechanisms to allergic diseases. Eosinophil/basophil-progenitor levels fluctuate in the peripheral blood during allergen exposure and the cells home to peripheral tissue, where they differentiate. It is becoming apparent that several cytokines, particularly IL-5, have multiple effects on progenitors and allergic inflammation. Within the past few years, studies of the therapeutic implications of this bone marrow contribution to atopy have been initiated; the effects of corticosteroids, leukotriene-receptor blockers, antagonism of IL-5 and modulation of differentiation by retinoic acid on progenitors will be reviewed.

Prenatal and early-life predictors of atopy and allergic disease in Canadian children: results of the Family Atherosclerosis Monitoring In earLY life (FAMILY) Study.

Prenatal and early-life environmental exposures play a key role in the development of atopy and allergic disease. The Family Atherosclerosis Monitoring In earLY life Study is a general, population-based Canadian birth cohort that prospectively evaluated prenatal and early-life traits and their association with atopy and/or allergic disease. The study population included 901 babies, 857 mothers and 530 fathers. Prenatal and postnatal risk factors were evaluated through questionnaires collected during the antenatal period and at 1 year. The end points of atopy and allergic diseases in infants were evaluated through questionnaires and skin prick testing. Key outcomes included atopy (24.5%), food allergy (17.5%), cow's milk allergy (4.8%), wheezing (18.6%) and eczema (16%). The association between infant antibiotic exposure [odds ratio (OR): 2.04, 95% confidence interval (CI): 1.45-2.88] and increased atopy was noted in the multivariate analysis, whereas prenatal maternal exposure to dogs (OR: 0.60, 95% CI: 0.42-0.84) and acetaminophen (OR: 0.68, 95% CI: 0.51-0.92) was associated with decreased atopy. This population-based birth cohort in Canada demonstrated high rates of atopy, food allergy, wheezing and eczema. Several previously reported and some novel prenatal and postnatal exposures were associated with atopy and allergic diseases at 1 year of age.

Basophil production III: relation of histamine to guinea pig basophil growth in vitro.

Histamine has been measured by an isotopic enzyme conversion assay in guinea pig bone marrow cultures under conditions which stimulate basophilopoiesis. A high degree of correlation was observed between histamine values and basophil counts in suspension cultures. Cultures of normal marrow with splenic conditioned medium (CM) prepared from spleen cells of ovalbumin (OA)-treated animals or coculture of marrow cells from these animals with autologous spleen cells demonstrated rises in histamine values which paralleled basophil counts, with a mean calculated histamine of 0.3 pg/basophil. Addition to marrow cells from OA-treated animals of autologous splenic T-lymphocytes or culture of normal marrow in the presence of CM derived from PHA-stimulated splenic T-lymphocytes caused in vitro increases in histamine significantly greater than when T-lymphocyte depleted spleen cells or CM derived from the latter were used, respectively (P less than 0.02). The presence of OA in marrow-spleen cultures significantly enhanced basophilopoiesis when whole or T-enriched, but not T-depleted, spleen fractions were used (P less than 0.02). The magnitude of in vitro increases in histamine over one week was 10-30 nanograms, accompanied by appropriate increases in basophils in CM-stimulated normal marrow cultures. From these data it can be concluded that histamine is an independent criterion of basophilopoiesis in vitro. An entirely new population of histamine-synthesizing cells appears to arise over 1 week in vitro under conditions of antigen or T-cell product stimulation.

Clonal origin of human basophil/mast cells from circulating multipotent hemopoietic progenitors.

The origin of the human basophil/mast cell lineage from a pluripotent hematopoietic stem cell has been surmised but never demonstrated. By examining individual hemopoietic colonies in methylcellulose under inverted microscopy and using histochemical stains in conjunction with single-colony histamine assays, we have previously identified basophil/mast cell progenitors in human peripheral blood. We now report that a large proportion of normal human peripheral blood mixed granuloerythropoietic (GEMM) colonies contain histamine, in contrast to a significantly lower frequency of histamine positivity among normal neutrophil-macrophage, eosinophil, erythroid, macrophage, or megakaryocyte colonies. Morphological observations confirmed the presence of basophil/mast cells in the majority of GEMM colonies. In our work, the clonal derivation of basophils/mast cells from circulating multipotent (CFU-GEMM) hemopoietic stem cells was formally demonstrated, using combined histamine and G6PD isoenzyme analysis of single colonies grown in methylcellulose from a normal G6PD heterozygote.

Reciprocal regulation of human basophil and eosinophil differentiation by separate T-cell-derived factors.

Basophil and eosinophil progenitors are present in human hemopoietic tissues, including cord blood. In the present studies, cord blood cultures demonstrating differentiation of basophils or eosinophils have been maintained for prolonged periods in the presence of conditioned medium from a human T-cell leukemia line (Mo-CM). Peak basophil counts and histamine levels were followed almost invariably by a second peak of eosinophils in vitro. Morphologic examination revealed the consistent presence of cells with mixed basophil-eosinophil granulation. Both basophil and eosinophil growth-stimulating activities were found in Mo-CM, were heat stable and nondialyzable, and could be partially separated from each other by a multistep procedure that included ion-exchange chromatography on DEAE-cellulose. Mixing experiments using separated basophil- and eosinophil-stimulating activities revealed that suppression of basophil growth was accompanied by reciprocal enhancement of eosinophil growth, a finding that could be confirmed on analysis of morphology of single colonies from cord blood progenitors in methylcellulose. These studies point to the existence of regulatory growth factors in Mo-CM that stimulate and/or inhibit the growth and differentiation of human basophils and eosinophils from a common, committed progenitor cell.