UMLS:C0029713 - FACTA Search

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Query: UMLS:C0029713 (immaturity)
4,335 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

It is now generally accepted that maturational immaturity of lung defense system(s) exists in the young infant and child which, together with other maturational deficiencies of immunologic systems, contribute to their undue susceptibility to infections, many of which are associated with pulmonary infections. The alveolar macrophage (AM), of central importance to lung defense, has been studied extensively in the neonatal rabbit by our group and in the human, by others. Collectively, the results indicate small numbers of morphologically and functionally immature AMs prior to birth followed by a dramatic increase within the first 24 hr. This increase coincides with the large release from type II cells of surfactant, which not only may be involved in the functional maturation of developing AMs but also, if present in large quantities, may lead to decreased activity of these cells. There is also an age-related increase in chemotactic and microbicidal activity of AMs during maturation. Deficiencies in bone marrow pools, complement and cytokines (IFN-gamma, TNF-alpha) as well as IgG isotype switching are known to occur in the neonate which may contribute to increased susceptibility to infection and which are amenable to immune interventions.
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PMID:Developmental aspects of pulmonary defenses in children. 754 59

Loxoribine is a potent new immunostimulant with a relatively broad spectrum of immunobiological activities. Both loxoribine and its analogues function as agonists of immune responses in a variety of species, including humans. They upregulate the activity of B cells, T cells, NK cells, macrophages, and LAK cells. Induction of enhanced cytokine secretion has been found to involve IFN-alpha/beta, IFN-gamma, TNF-alpha, TNF-beta, IL-1, IL-6, and the 40 kDa chain of IL-12. Evaluation of in vivo activity has been undertaken only for antibody production, NK cell-mediated cytotoxicity, induction of certain cytokines, and LAK cell-mediated cytotoxicity; all four types of activity are markedly upregulated by loxoribine in vivo. Augmentation of antibody production has been observed for protein, recombinant protein, and synthetic peptide antigens, among others. Because loxoribine and its analogues transmit a T-helper-like signal to antibody-producing B cells, it is a highly effective adjuvant even for synthetic peptides that lack T-cell epitopes, effectively replacing the function of T-helper cells in this milieu. It thus provides an alternative, T-cell-independent vaccination strategy if it becomes desirable to avoid untoward T-cell-mediated effects, or in patients with functional or absolute T-cell deficiency. There are a number of features unique to loxoribine that are highly advantageous under specific circumstances: (1) T cell independence; (2) loxoribine augments antibody responses from an intracellular location (rather than at the surface membrane), independently of protein kinase C involvement; this may be particularly relevant for patients with membrane receptor/signal transduction defects; (3) adjuvanticity of loxoribine is essentially free of cytokine dependency; this may be of particular value for organ transplantation patients whose cytokine-dependent immunity is pharmacologically suppressed; (4) loxoribine bypasses functional immunological immaturity, rendering it particularly useful for vaccines in infants. In preclinical safety studies, the drug has exhibited a relatively benign profile. Phase I clinical studies to date have produced no toxicity higher than grade 1. The drug appears to be quite stable, and compares very favorably in direct evaluations with a number of other immunostimulators. A number of clinical trials have been planned for the future.
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PMID:A new approach to vaccine adjuvants. Immunopotentiation by intracellular T-helper-like signals transmitted by loxoribine. 755 Dec 37

Respiratory infections are the major cause of disease in childhood in the industrialized areas of the world. This essentially depends on two factors: immunological immaturity and immunological naivety. In most cases a virus has been considered the causative agent in respiratory infection. A defect in immune responses has been described in children with recurrent respiratory infections and in particular a decrease in CD4/CD8 T lymphocyte ratio or in IL-2 and IFN-gamma production. Our results show that Natural Killer (NK) cell activity is defective in children with recurrent respiratory infections. That is particularly noteworthy since NK cells play an important role in host defense against viral infections. At present it is difficult to understand whether the NK defect is a primary defect or it is secondary to viral infections. Further studies will help to clarify whether NK decreased activity depends on a cell damage directly caused by virus or it depends on the decreased levels of cytokines.
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PMID:[Reduced natural killer function in children with recurrent respiratory tract infections]. 848 16

Interleukin-12 (IL-12) is a critical cytokine regulating natural killer (NK) and T-cell function. We hypothesized that the impaired ability of cord blood (CB) to produce normal adult levels of IL-12 in response to stimulation may contribute to the immaturity of CB immunity. Furthermore, exogenous IL-12 may compensate for the immaturity in CB cellular immunity and have the potential for immunotherapy post cord blood transplantation. We compared the expression and production of IL-12 from activated cord versus adult mononuclear cells (MNC), regulatory mechanisms associated with IL-12 expression in CB MNC, and the effects of IL-12 on induction of CB interferon (IFN)-gamma production, NK, and lymphokine-activated killer (LAK) cytotoxicity. Northern analysis and enzyme-linked immunosorbent assay were performed in lipopolysaccharide (LPS)-stimulated CB and adult peripheral blood (APB) MNC. IL-12 mRNA expression was induced within 6 hours with LPS (10 micrograms/ml) and reached peak levels at 12 hours in both CB and APB MNC. However, IL-12 mRNA expression and protein accumulation in CB MNC were 35.8% +/- 4.84% (12 hours, n = 11, P < .05), and 17.6% +/- 1.7% (24, 72, 96 hours, n = 9, P < .05) respectively, when compared with APB MNC. Nuclear run-on assays showed no differences between CB and APB MNC in both the basal levels of transcription and the degree of transcriptional activation. However, the half-life of IL-12 p40 mRNA was approximately threefold lower in activated CB MNC than in activated APB MNC (CB: 114 +/- 3.0 minutes v APB: 353 +/- 7.8 minutes, n = 3, P < .05). Exogenous IL-12 (10 U/mL) induced a significant increase of IFN-gamma from both CB and APB MNC (24 hours, 72 hours, P < .05, n = 3). The stimulated CB IFN-gamma level reached comparable levels produced by unstimulated APB. IL-12 treatment also significantly enhanced CB NK cytotoxicity against K562 and NB-100 cell lines to the comparable levels of APB (P < .05, n = 4). CB MNC was more responsive to IL-12 stimulation with respect to IFN-gamma production, NK, and LAK cytotoxicity when compared with APB. The present study suggests that IL-12 mRNA and protein expression is decreased in activated CB. This discrepancy in IL-12 production is secondary, at least in part, to the altered posttranscriptional regulation. The impaired, ability of CB MNC to produce IL-12 in response to stimulation may contribute to the decrease in IFN-gamma production and NK cytotoxicity. However, IL-12 enhanced IFN-gamma and NK activity in CB MNC up to the comparable levels of APB MNC. These findings suggest that reduced expression and production of IL-12 from activated CB may contribute to the immaturity in CB cellular immunity and contribute, in part, to decreased graft-versus-host disease following CB stem cell transplantation.
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PMID:Decreased interleukin-12 (IL-12) from activated cord versus adult peripheral blood mononuclear cells and upregulation of interferon-gamma, natural killer, and lymphokine-activated killer activity by IL-12 in cord blood mononuclear cells. 870 53

Severe viral infection in newborns has been attributed to immaturity of the immune system including a defect in natural killer cytotoxicity (NKC) and decreased production of cytokines that are important for natural killer (NK) function. We investigated the induction of interferon (IFN)-gamma and activation of NK activity in adult and cord blood mononuclear cells (BMC) after IL-12 treatment. The levels of mRNA in these BMC were measured by Northern blot and reverse transcription-polymerase chain reactions using primers specific for IFN-gamma. The levels of IFN-gamma protein were measured by ELISA. In the absence of IL-12, only adult BMC spontaneously produced low levels of IFN-gamma. After IL-12 treatment, induction of IFN-gamma expression was detected as early as 4 h in both cord and adult BMC. Both cord and adult cells showed similar levels of IFN-gamma mRNA and protein expression in response to IL-12 at a concentration as low as 10 U/mL. In contrast, upon phorbol ester and ionomycin treatment, adult BMC produced more IFN-gamma mRNA than cord BMC. In a 51Cr release assay with human immunodeficiency-infected H9 cells as indicators, both cord and adult cells responded to IL-12 induction of NKC. Our findings demonstrate that cord BMC are capable of responding to IL-12 stimulation, competent in synthesizing IFN-gamma, and able to mount NKC. Thus, it appears that the deficiency in IFN-gamma production or NKC in cord cells is not due to an inherent defect in IL-12 response of the cord cells.
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PMID:Interleukin-12 induces interferon-gamma expression and natural killer cytotoxicity in cord blood mononuclear cells. 882 1

The newborn immune system differs quantitatively and functionally from that of adults. Development of the immune system has important implications for childhood diseases. The immaturity of the immune system in the first years of life may contribute to failure of tolerance induction and in the development of allergic disease. T cell function is diminished, especially the capacity to produce cytokines; production of interferon (IFN)-gamma, and IL-4 is strongly reduced. IFN-gamma has been found to be even lower in cord blood of newborns with a family history of atopy. Differences in other cell types (natural killer cells, antigen-presenting cells, and B cells) could also play a role in the development of allergic disease. Current data suggest that irregularities in IgE synthesis, helper T cell subsets (Th1, Th2, CD45RA, and CD45RO), cytokines (IL-4, IFN-gamma), and possibly other cell types may play a role in the development of allergy in childhood. Moreover, the role of cell surface molecules, like co-stimulatory molecules (CD28, CD40L), activation markers (CD25), and adhesion molecules (LFA-1/ICAM-1, VLA-4/ VCAM-1) is also discussed. These variables are modulated by genetic (relevant loci are identified on chromosome 5q, 11q, and 14) and environmental forces (allergen exposure, viral infections, and smoke). The low sensitivity of current predictive factors for the development of allergic diseases, such as cord blood IgE levels, improves in combination with family history and by measurement of in vitro responses of lymphocytes and skin reactivity to allergens. New therapeutic approaches are being considered on the basis of our current understanding of the immunopathology of allergic disease, for instance cytokine therapy and vaccination with tolerizing doses of allergen or peptides.
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PMID:Development of immune functions related to allergic mechanisms in young children. 886 70

The physiologically low or absent IgG2 responses of infants have been attributed to T or B cell functional immaturity. We have analyzed the capacity of adult and neonatal T lymphocytes to secrete IgG2 switch factor (IgG2-SF) and the capacity of neonatal B cells to respond to such factors. The IgG2-SF capacity was assessed on CD40-activated naive B cells, measuring IgG2 by ELISA in supernatants of cultures performed in the presence of IL-10. T cells secreted IgG2-SF together with IL-2 and IFN-gamma, after activation with a combination of anti-CD2, anti-CD28 and phorbol myristate acetate (Th1-like activation). In contrast, activation with anti-CD3 and anti-CD28, which yielded IL-4 and IL-10 but neither IL-2 nor IFN-gamma (Th2-like activation), did not result in the secretion of IgG2-SF. The supernatant of activated neonatal T cells contained IgG2-SF. Neonates' B cells produced almost as much IgG2 as did naive adult B cells. The effect of IgG2-SF was further demonstrated by its ability to induce 3-15% of CD40-activated naive B cells to express cytoplasmic IgG2 regardless of the presence of IL-10. This study demonstrates that: (i) IgG2 switch can be T cell dependent in humans, (ii) IgG2-SF is produced with Th1-like cytokines and (iii) low IgG2 responses in infants do not result from either an inability of T cells to produce IgG2-SF or an inability of B cells to undergo IgG2 switch in vitro.
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PMID:Delayed IgG2 humoral response in infants is not due to intrinsic T or B cell defects. 892 28

The early development of symptoms and the rapid progression of disease in some vertically infected infants are thought to reflect in part the immaturity of their immune systems. We examined the relationship between HIV-specific CTL activity and the profile of cytokine production induced by mAb to CD3 and HIV envelope (env) peptides P18 and T1 in PBMC derived from 0.6- to 3.6-yr-old children with perinatal HIV infection. Cellular immunity against HIV was demonstrated only during early stages of disease, whereas the responses were either undetectable or at background levels in HIV-infected children with rapidly progressing disease and in uninfected children of HIV+ and HIV- mothers. Levels of IL-2 mRNA in anti-CD3 mAb- and env peptide-induced PBMC varied and were increased in the infected children with high frequencies of HIV-specific CTL precursors. Analysis of IFN-gamma and IL-4 production by CD4+ T cell clones obtained from cultures stimulated with anti-CD3 mAb or the env peptides showed an increased proportion of Th2 and Th0 clones in HIV-infected children with lower HIV-specific CTL activity, whereas children with high CTL activity had increased numbers of Th1 clones. The results of these studies suggest that decreases in CTL activity to the virus might be associated with the induction of a type 2 cytokine response. These findings underline the role of cytokines in the generation of HIV-specific CTL responses and may be important for the development of immunomodulatory and vaccine strategies to interrupt vertical transmission of HIV.
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PMID:Diminished HIV-specific CTL activity is associated with lower type 1 and enhanced type 2 responses to HIV-specific peptides during perinatal HIV infection. 919 Sep 58

Interleukin 12 (IL-12) is a pleiotropic cytokine and mediates several biological activities on human T and natural killer (NK) cells, including induction of IFN-gamma production, enhancement of cell-mediated cytotoxicity and comitogenic effects on resting T-cells. The major cellular sources producing IL-12 are antigen-stimulated monocytes, macrophages, and B-cells isolated from peripheral blood mononuclear cells (PBMC). Our laboratory has investigated the regulation of IL-12 gene expression in both cord blood and adult PBMC, and the effects of IL-12 on induction of IFN-gamma production, NK, and lymphokine-activated killer (LAK) cytotoxicity. IL-12 mRNA expression and protein production in LPS-stimulated cord blood MNC were 3-4 fold decreased when compared with adult PBMC. There were no differences between cord blood and adult PBMC in both basal levels of transcription or the degree of transcriptional activation of the IL-12 gene. Additionally, the half-life of IL-12 p40 mRNA was 3-fold lower in activated cord blood compared to adult PBMC. Exogenous IL-12 induced a significant increase of IFN-gamma from both cord and adult PBMC. Cord MNC has significantly reduced levels of NK activity, and IL-12 significantly enhanced cord blood NK cytotoxicity up to similar levels in adult PBMC. IL-12 also significantly enhanced cord blood NK and LAK activities against a broad range of neuroblastoma, leukemia, and lymphoma cell lines. Lower doses of IL-12 and IL-15 concomitantly generated either synergistic or additive effects on cord blood NK and LAK cytotoxicities. In light of the important biological functions of IL-12, reduced expression and production of IL-12 from activated cord blood may contribute to the immaturity of cord blood cellular immunity and contribute, in part, to decreased severe graft vs. host disease following unrelated cord blood stem cell transplantation. IL-12 enhancement of IFN-gamma, NK, and LAK activity in activated cord blood MNC up to comparable levels in adult PBMC suggests that exogenous IL-12 stimulation can compensate for the immaturity in cord blood cellular immunity. These characteristics of IL-12 biological activity strongly suggest its potential usefulness in future cancer immunotherapy.
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PMID:The regulation and biological activity of interleukin 12. 964 57

Haematopoiesis and immune functions in cord blood (CB) are developmentally immature when compared with adult peripheral blood (APB). The defects in CB immune function and cytokine production may both contribute to the immaturity of CB immunity. We have studied the mechanisms associated with the dysregulation of myeloid lineage cytokines, GM-CSF and M-CSF, and lymphokines, IL-12, and IL-15 in activated CB when compared with APB MNC. Furthermore, we have studied the effects of IL-12 and IL-15 on induction of IFN-gamma and TNF-alpha production, NK, and LAK activities in CB and APB. GM-CSF, M-CSF, IL-12 and IL-15 protein and mRNA are decreased in activated CB MNC. These discrepancies are secondary, at least in part, to the altered post-transcriptional regulation. The impaired ability of CB to produce IL-12 and IL-15 in response to stimulation may contribute to the decrease in IFN-gamma, TNF-alpha production, NK and LAK activities. Furthermore, combination of low dose IL-12 and IL-15 may augment cytotoxic activities and minimize toxicity. These findings suggest that reduced cytokine expression from activated CB may contribute to the impaired CB cellular immunity and exogenous lymphokines may compensate for the immaturity in CB.
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PMID:Dysregulation of lymphokine production in the neonate and its impact on neonatal cell mediated immunity. 971 74

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