Association of decreased T-cell-mediated natural cytotoxicity and interferon production in Down's syndrome

Hirschsprung's disease associated enterocolitis: A comprehensive review

Hirschsprung's disease (HSCR) is a congenital disorder characterized by failure of the neural crest cells to migrate and populate the distal bowel during gestation affecting different lengths of intestine leading to a distal functional obstruction. Surgical treatment is needed to correct HSCR once the diagnosis is confirmed by demonstrating the absence of ganglion cells or aganglionosis of the affected bowel segment. Hirschsprung's disease associated enterocolitis (HAEC) is an inflammatory complication associated with HSCR that can present either in the pre- or postoperative period and associated with increased morbidity and mortality. The pathogenesis of HAEC remains poorly understood, but intestinal dysmotility, dysbiosis and impaired mucosal defense and intestinal barrier function appear to play a significant role. There is no clear definition for HAEC, but the diagnosis is primarily clinical, and treatment is guided based on severity. Here, we aim to provide a comprehensive review of the clinical presentation, etiology, pathophysiology, and current therapeutic options for HAEC.

Hemophagocytic lymphohistocytosis in trisomy 21: successful treatment with interferon inhibition

BACKGROUND

Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening condition of immune dysregulation primarily driven by the cytokine interferon gamma. It can be either a genetic or acquired disorder associated with infection, malignancy, and rheumatologic disorders. Trisomy 21 can express a wide range of phenotypes which include immune dysregulation and shares inherent pathophysiology with a group of disorders termed interferonopathies. Knowledge of this overlap in seemingly unrelated conditions could provide a basis for future research, and most importantly, alternative therapeutic interventions in acute life threatening clinical scenarios. Herein, we describe two patients with trisomy 21 presenting with HLH that was refractory to conventional treatment. Both patients were successfully managed with novel interventions targeting the interferon pathway.

CASE PRESENTATION

We describe a 17-month-old male and 15-month-old female with trisomy 21 presenting with a myriad of signs and symptoms including fever, rash, cytopenias, and hyperferritinemia, both ultimately diagnosed with HLH. Each had relapsing, refractory HLH over time requiring several admissions to the hospital receiving conventional high dose corticosteroids and interleukin-1 inhibition therapy. Successful steroid-free remission was achieved after targeting interferon inhibition with emapalumab induction followed by long-term maintenance on baricitinib.

CONCLUSION

To our knowledge, these are the first reported cases of relapsed, refractory HLH in patients with trisomy 21 successfully treated with emapalumab and transitioned to a steroid-sparing regimen with oral baricitinib for maintenance therapy. Trisomy 21 autoimmunity and HLH are both thought to be driven by interferon gamma. Targeting therapy toward interferon signaling in both HLH and autoimmunity in trisomy 21 may have potential therapeutic benefits. Further investigation is needed to determine if trisomy 21 may predispose to the development of HLH given this common pathway.

Current understanding of Hirschsprung-associated enterocolitis: Pathogenesis, diagnosis and treatment

Hirschsprung-associated enterocolitis (HAEC) was described in 1886 by Harald Hirschsprung and is a potentially deadly complication of Hirschsprung Disease. HAEC is classically characterized by abdominal distension, fever, and diarrhea, although there can be a variety of other associated symptoms, including colicky abdominal pain, lethargy, and the passage of blood-stained stools. HAEC occurs both pre-operatively and post-operatively, is the presenting symptom of HSCR in up to 25% of infants and varies in overall incidence from 20 to 60%. This article reviews our current understanding of HAEC pathogenesis, diagnosis, and treatment with discussion of areas of ongoing research, controversy, and future investigation.

Immune Dysregulation in Children With Down Syndrome

Down syndrome (DS) is the most common genetic syndrome associated with immune defects. The extent of immune dysregulation in DS is substantial, spanning the innate and adaptive systems and including anomalies in: T and B cells, monocytes, neutrophil chemotaxis, circulating cytokines, and suboptimal antibody responses which all contribute to an increased risk of infections, poorer clinical outcomes and chronic inflammation in this vulnerable cohort. Other aspects of innate immunity may also be abnormal and contribute to the increased morbidity and warrant further interrogation such as: gamma delta T cell function, the inflammasome, Toll-like receptors and their pathways. Pharmacotherapies such as pavilizumab, pneumococcal and influenza immunizations, as well as potential immunoprophylactic agents such as pidotimod, azithromycin and Broncho-Vaxom may help alleviate the infectious consequences. Children with DS need to be managed with a heightened sense of awareness and urgency in the setting of sepsis and signs of chronic inflammation need regular screening and appropriate follow up.

Hirschsprung's disease associated with Down syndrome: a meta-analysis of incidence, functional outcomes and mortality

PURPOSE

Down syndrome (DS) is the most frequent chromosomal abnormality associated with Hirschsprung's disease (HD). It has often been suggested that this association results in poorer outcomes with regard to postoperative complications, continence and mortality. On the other hand, the results after surgical treatment of HD in patients with DS are reportedly similar to those in cases with HD alone. The objective of this study was to determine the incidence of DS in cohorts with HD, and to compare pre-/postoperative complications, functional outcome and mortality between cohorts with and without coexisting DS.

METHODS

A systematic literature-based search for relevant cohorts was conducted using multiple online databases. The number of DS cases in HD cohorts was recorded and data on pre-/postoperative complications, functional outcome and mortality were extracted. Pooled odds ratios with 95% confidence intervals were calculated using meta-analysis methodology.

RESULTS

Sixty-one articles met defined inclusion criteria, comprising data from 16,497 patients with HD. The overall incidence of DS among them was 7.32%. Vice versa, the incidence of HD in 29,418 patients with DS was 2.62%. There were no significant differences regarding the male-to-female ratio between cohorts with and without coexisting DS (4:1 vs. 3:1 respectively; P = 0.5376). The rate of additional comorbidities was significantly higher in HD associated with DS (P < 0.0001). Recto-sigmoid HD was in both cohorts the most common type of HD (P = 0.8231). Long-segment HD was significantly more frequent in HD with coexisting DS (P = 0.0267), while total colonic aganglionosis occurred significantly more often in HD without DS (P = 0.0003). There were no significant differences in preoperative constipation/obstruction (P = 0.5967), but the rate of preoperative enterocolitis was significantly higher in HD associated with DS (P = 0.0486). Postoperative complications such as recurrent enterocolitis (P = 0.0112) and soiling (P = 0.0002) were significantly more frequent in HD with coexisting DS. Although not statistically significant, fecal incontinence (P = 0.1014) and persistent constipation (P = 0.1670) occurred more often after surgical treatment of HD with DS. The mortality rate was significantly higher in HD associated with DS (P < 0.0001).

CONCLUSIONS

The association of HD with DS is well-recognized with an incidence of 7.32%. A large number of patients with DS continue to have persistent bowel dysfunction after surgical treatment of HD. Our data provide strong evidence that the coexistence of HD and DS is associated with higher rates of pre-/postoperative enterocolitis, poorer functional outcomes and increased mortality.

The pathogenesis of Hirschsprung's disease-associated enterocolitis

Hirschsprung's disease-associated enterocolitis (HAEC) remains the most life-threatening complication in Hirschsprung disease (HD) patients. The pathogenesis of HAEC has not been determined and many hypotheses regarding the etiology of HAEC have been proposed. These include a possible causal relationship between the abnormal enteric nervous system development in HD and the development of enterocolitis. Based on the complex genetic causes of HD that have been discovered and the resultant heterogeneous group of patients that exists, the causes of HAEC are likely multiple. New insights regarding the relationship of the role of the enteric nervous system and its interaction between intestinal barrier function, innate host immunity, and commensal microflora have been discovered, which may shed light on this perplexing problem. This review presents current known risk factors of HAEC and the proposed theories and supporting evidence for the potential etiologies of HAEC.

Hirschsprung-associated enterocolitis develops independently of NOD2 variants

BACKGROUD/PURPOSE: Hirschsprung-associated enterocolitis (HAEC) represents a cause for significant pre- and postoperative morbidity and mortality in Hirschsprung disease (HD). Although multiple studies on HAEC have been performed and several mechanisms have been presumed, the pathogenesis of this condition remains unclear. As changes in colonic mucosal defense are key factors suggested in both Crohn's disease (CD) and HAEC pathogenesis, the aim of the current study was to investigate genetic alterations in the most important susceptibility gene for Crohn's enterocolitis (NOD2) to see whether carriers of polymorphisms within the NOD2 gene are predisposed to the development of HAEC.

METHODS

Genotyping for the NOD2 variants in exon 4 (p.Arg702Trp [rs2066844]), exon 8 (p.Gly908Arg [rs2066845]), and exon 11 (p.1007fs [rs2066847]) was performed in 52 white children with HD (41 boys, 11 girls), 152 healthy controls, and 152 children with CD (onset of disease <17 years; mean, 11.8 years). Seventeen patients with HD (32.7%) were carriers of a RET germline mutation, 35 children (67.3%) had short segment disease, and 17 (32.7%) had long segment disease.

RESULTS

Ten children (19.2%) with HD were heterozygous carriers of at least one NOD2 variant vs 17 (11.2%) in the healthy control group and 69 (45.4%) in the CD cohort. Hirschsprung-associated enterocolitis was observed in 7 children (13.5%), with 4 having short segment HD and 3 with long segment HD; but none of them were carriers of NOD2 variants.

CONCLUSION

Our study shows that NOD2 variants described to be causatively associated with CD do not predispose to the development of HAEC. As data on the molecular basis of HAEC are limited, the distinct mechanisms involved in the pathogenesis of this complication remain unclear.

New insights into the pathogenesis of Hirschsprung's associated enterocolitis

The management of Hirschsprung's disease (HD) has made dramatic strides over the last 20 years. Research into the embryological development and migration of ganglion cell has enabled a greater understanding of the pathogenesis of the disease. Coupled with new techniques in surgery, such as laparoscopy-assisted pull-through and the transanal pull-through, this knowledge has led to improved outcomes for children with HD. However, although our appreciation of Hirschsprung's associated enterocolitis and its aetiology has increased, there are continued references in the literature to a multitude of theories of pathogenesis. The purpose of this review is to delineate the theories and demonstrate the evidence supporting or otherwise contradicting each other.

Immunology of Down syndrome: a review

Subjects with Down syndrome (DS) have a high mortality due to infections and a high risk of developing malignancies. These observations, together with the demonstration of a frequent occurrence of HBsAg carrier state and of autoantibodies, have prompted investigations of the immune function in DS. Thymic morphological and functional abnormalities have been demonstrated. Peripheral blood mononuclear cells of DS subjects have been shown to include a high number of T lymphocytes with low avidity for sheep erythrocytes and a very high percentage of cells with an NK phenotype. However, NK activity is low in DS. Production of some important cytokines, such as IL-2, is depressed, thus contributing to T-cell derangement. Abnormalities of the B-cell compartment were also demonstrated, with a tendency towards high IgG and low IgM serum levels. Controversial results have been obtained with regard to antigen-specific antibody response. Also phagocytes of DS subjects display some characteristic functional impairments, with low chemotactic ability and reduced production of oxygen radicals. Despite the clearly established and rather detailed evidence of immune derangements, therapeutic trials have been anecdotal and resulted in marginal effects. HBV vaccination is highly advisable in DS because of the high risk of becoming chronic HBV carriers once infected.

Enterocolitis complicating Hirschsprung's disease

Enterocolitis remains a relatively common complication of Hirschsprung's disease with significant morbidity and mortality. The etiology of Hirschsprung's enterocolitis (HEC) is multifactorial and remains poorly understood. Preventative measures and better treatment modalities will evolve out of a better understanding of the underlying pathophysiology. Prompt recognition of HEC allows early intervention and a potential reduction in disease severity and mortality. This review of HEC describes the epidemiology, clinical and pathological features and current best practice in management. Some of the areas of research into etiology and treatment are discussed.

Enhancement of natural killer cell activation and antibody-dependent cellular cytotoxicity by interferon-alpha and interleukin-12 in vaginal mucosae Sivmac251-infected Macaca fascicularis

We studied the innate immune system of Cynomolgus monkeys (Macaca fascicularis) experimentally infected via the vaginal mucosae with a virulent simian immunodeficiency virus isolate SIVmac251. Animals were evaluated for their natural killer (NK) cell activity, and for their antibody-dependent cellular cytotoxicity. NK cells from SIVmac251-infected macaques show impaired NK cell activity compared to cells from uninfected animals. Subsequent treatment of NK cells with interferon-a (IFN-alpha) or interleukin-12 (IL-12) alone partially restored the NK activity. However, either treatment of NK cells with both IFN-alpha and IL-12 completely reversed the impairment of cytotoxicity induced by simian immunodeficiency virus (SIV) infection. Incubation of NK cells from infected but not from uninfected monkeys with IFN-alpha and IL-12 for 8 days increased the percentage of CD16+/CD56+ cells twofold to five-fold and enhanced antibody-dependent cellular cytotoxicity (ADCC) activity. Thus IFN-alpha and IL-12 greatly enhance both the NK cell and ADCC activities of peripheral blood cells from SIVmac251-infected animals and increase the number of NK cells in longer term culture. The combined effect of IFN-alpha and IL-12 in enhancing NK cell activity may provide a novel therapeutic approach for the restoration of depressed NK cell activity observed in human immunodeficiency virus (HIV)-infected patients.

Sodium cromoglycate in the management of chronic or recurrent enterocolitis in patients with Hirschsprung's disease

BACKGROUND/PURPOSE

Chronic or recurring enterocolitis is a rare but perplexing complication of Hirschsprung's disease affecting especially patients with altered immune defense such as those with Down's syndrome. Sodium cromoglycate (SCG) is a nonabsorbable mast cell stabilizing agent that has been documented to be effective in the treatment of inflammatory bowel disease. The authors studied the effect of SCG in Hirschsprung patients with refractory chronic or recurrent enterocolitis.

METHODS

Eight patients (4 with Down's syndrome, 2 with other chromosomal aberrations, 2 otherwise healthy; age range from 4 to 22 years) with chronic (5 patients) or recurrent (>6 episodes/year, 3 patients) enterocolitis received 100 to 200 mg of SCG 4 times a day depending on the age of the patient. The chronic diarrhea or recurrent bouts of enterocolitis in the patients were refractory to dietary management and enteral antibiotics. Before the treatment all patients had ileocolonoscopy, the results of which showed macroscopic and histological chronic inflammation in all cases. No neuronal abnormalities were detected in biopsy results. None of the patients had colonic dilatation or increased anorectal resting pressures suggesting outlet obstruction.

RESULTS

The follow-up of the patients ranges from 8 months to 26 months. Three of the 5 patients with chronic enterocolitis responded favorably. In these 3 patients the median number of daily bowel movements decreased from 6 to 3, and none experienced bouts of abdominal distension. Diarrhea-related soiling decreased also significantly. Two of the 3 patients with recurrent enterocolitis have remained asymptomatic, and none has required antibiotics after the onset of SCG treatment; one patient had an episode of enterocolitis after 12 months treatment. Two patients with chronic enterocolitis did not respond to SCG. No side effects of SCG were encountered.

CONCLUSIONS

This preliminary and nonrandomized study suggests that SCG is an effective treatment modality for chronic or recurrent enterocolitis in patients with Hirschsprung's disease. Because SCG is not absorbed From the intestinal tract there are no systemic side effects.

Enterocolitis

Enterocolitis continues to be the major cause of morbidity and mortality in patients with Hirschsprung's disease. The exact etiology of Hirschsprung's-associated enterocolitis is not known. This review focuses on the clinical aspects, etiology, and therapy of Hirschsprung's-associated enterocolitis.

Allogeneic marrow grafts from donors with congenital chromosomal abnormalities in marrow cells

To determine whether siblings with chromosomal abnormalities in marrow cells which are associated with cellular defects (e.g. Down syndrome or heterozygosity for Fanconi syndrome) are suitable donors for allogeneic bone marrow transplants, we have reviewed the patient files at the Fred Hutchinson Cancer Research Center (FHCRC) and carried out a survey among member centres of the International Bone Marrow Transplant Registry (IBMTR). The 57 of 253 (23%) member centres which responded to the survey reported seven transplants from donors with the following conditions: Down syndrome (n = 2), suspected heterozygotes for Fanconi syndrome (n = 3), and 47,XXX syndrome (n = 2), among a total of 5,561 allogeneic transplants from HLA-identical siblings. Adding the three cases seen at the Fed Hutchinson Cancer Research Center among 2,927 HLA-identical sibling transplants during 1992 resulted in 10 transplants among 8,488 cases transplanted overall: four with Down syndrome, four suspected of being heterozygous for Fanconi syndrome, and two trisomy X. Three out of four grafts from siblings with Down syndrome had complications, including poor graft function (n = 2) and graft failure (n = 1). Two of four recipients of marrow from presumed Fanconi syndrome heterozygotes presented with poor graft function and a third recipient developed graft failure after initial evidence of engraftment. The two patients given marrow from siblings with 47,XXX syndrome engrafted uneventfully. The experience reported here shows a low frequency of encountering an HLA-identical sibling donor who has chromosomal abnormalities in marrow cells consistent with Down syndrome or heterozygosity for Fanconi syndrome, about one case among 1,000 transplants. The much higher than expected incidence of graft problems with marrow from such a donor would make it reasonable to look either for an alternative marrow donor or consider an autologous transplant, in case a sibling marrow donor with Down syndrome or heterozygosity for Fanconi syndrome is encountered, although a donor with trisomy X seems acceptable.

The influence of trisomy 21 on outcome in children with Hirschsprung's disease

The association of Hirschsprung's disease (HD) and trisomy 21 has been well recognised. Seventeen (13%) of 135 patients presenting with HD between 1975 and 1992 had trisomy 21. Nine (53%) presented in the neonatal period, with intestinal obstruction (5), enterocolitis (2), or perforation of the colon (2). Eight patients presented after the neonatal period, with constipation. Pathological involvement included rectosigmoid (12), long segment (4), and total colonic aganglionosis (1). Definitive surgery was performed in 14 patients. At the mean follow-up of 8 years (4 to 15 years), only one of the 13 patients has normal bowel function. Eight have persistent soiling, and two have reverted to permanent stomata. There were two deaths in the series; one resulted from enterocolitis complicating HD, and the other from congenital cardiac disease. These data suggest that long-term bowel function in children with HD and trisomy 21 is poor and should be taken into consideration when planning the management.

Intracellular calcium response is reduced in CD4+ lymphocytes in Alzheimer's disease and in older persons with Down's syndrome

Abnormalities in intracellular free calcium ([Ca2+]i) regulation are likely to play a role in brain aging and have been described in cells from patients with Alzheimer's disease (AD). [Ca2+]i acts as a second messenger in transmembrane signaling and regulates diverse functions in many cell types. Therefore, abnormalities in [Ca2+]i response may have far-ranging effects. Using flow cytometric assay for [Ca2+]i, we examined whether mitogen-induced increases in [Ca2+]i are abnormal in CD4+ T-lymphocytes from patients with familial AD (FAD), other AD, and Down's syndrome (DS) compared to age-matched controls. We observed that the peak [Ca2+]i responses were significantly decreased in CD4+ cells from 6 FAD patients (59% of control), 34 other AD patients (69% of age-matched control), and 6 older persons with DS (> 25 years old, 47% of control), after stimulation with 10 micrograms/ml anti-CD3 monoclonal antibody (mAb). The number of CD3 receptors on T lymphocytes of the AD patients was not decreased. In contrast, lymphocytes from subjects with FAD, other AD and older DS patients had no decrease in response to phytohemagglutinin (30 micrograms/ml). CD3 and related classes of membrane receptors are present on many cells of the central nervous system. Therefore, receptor signaling defects via this receptor in T lymphocytes of AD patients may be relevant to the central nervous system pathology seen in AD and DS.

Reduced natural killer cell activity in patients with dementia of the Alzheimer type

We examined the natural killer (NK) cell activity in 50 patients with dementia of the Alzheimer type (DAT) and 37 age-matched normal controls. The NK cell activity in DAT was significantly lower than in the normal controls. The NK cell activity induced by either interferon-alpha (IFN-alpha) or interleukin-2 (IL-2) in DAT was also significantly lower than in the normal controls. There were no significant differences in the level of serum IL-2 and IFN-alpha between the two groups. As regards NK cell subsets, two-color flow cytometric analysis showed no significant differences between the percentages of Leu-11+ Leu-7- cells, Leu-11+ Leu-7+ cells and Leu-11- Leu-7+ cells in the two groups. Our results suggest that NK cells in DAT may have functional abnormalities and may provide important clues to fundamental cellular and molecular aberrations in DAT.

Immunodeficiency and plasma zinc levels in children with Down's syndrome: a long-term follow-up of oral zinc supplementation

To evaluate the possible effect of zinc treatment on immune disorders in children with Down's syndrome (DS), 38 noninstitutionalized DS children were investigated. Twenty-four patients (63.2%) had plasmatic zinc levels lower than 0.70 microgram/dl ("hypozinkemic," LZn) and 14 patients (36.8%) had levels higher than 0.75 microgram/dl ("normozinkemic," NZn). No correlation was found between the zinc deficiency and recurrence and/or intensity of infections. The absolute numbers of peripheral lymphocytes, the percentages of B lymphocytes, total T cells, and serum IgG, IgA, and IgM levels did not differ between the DS children and the controls. Eight (21%) patients had CD4+ T cell counts below the lowest value for the controls. Seventeen (44%) DS patients had increased levels of CD8+ T cells. The mean percentage of Leu 7+ cells in DS subjects (22.8 +/- 12.9%) was significantly higher than that in controls (15.8 +/- 4.8%) (P less than 0.01). Notably, Ig levels and numbers of lymphocytes in each subset did not show any significant difference in NZn and LZn trisomic subjects. On the contrary the peripheral blood mononuclear cells (PBMCs) from LZn DS children showed a significantly lower proliferative response to phytohemagglutinin (PHA) (S.I. = 23.4 +/- 22.4) than that of PBMCs from NZn DS children (S.I. = 46.1 +/- 21.5, P less than 0.01). A significant increase in DNA synthesis was obtained after oral administration of zinc sulfate (20 mg/kg/day, for 2 months). The lymphocyte response to PHA appeared to be normal in all patients up to 6 months after the end of the zinc treatment and it became low in half of the patients 22 months after therapy.

The pathophysiology of Hirschsprung's-associated enterocolitis: importance of histologic correlates

To more clearly define the pathophysiology of Hirschsprung's-associated enterocolitis (HAEC), this study comprehensively evaluates the gastrointestinal tissue of a group of infants with clinical HAEC. A pathologic grading system that demonstrates a progressive sequence of histologic changes specific for HAEC is established. The grading system correlates closely with clinical enterocolitis and may prove to be a useful method for early detection of infants at risk for the development of clinical HAEC. A significant alteration of intestinal mucins with an increase in neutral mucins and a decrease in acidic-sulfomucins was identified in HAEC tissue specimens. Enterocyte-adherent organisms were present in 39% of HAEC tissue specimens. The pathogenesis of HAEC may result from an alteration in intestinal mucins that may allow for the subsequent adherence of enteropathogenic organisms to enterocytes. The enterocyte-adherent organisms have the potential to induce an enterocolitic process and may contribute to both the intestinal and systemic manifestations of HAEC.

Neopterin: biopterin ratios in Down's syndrome

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Immunological studies of patients with Down's syndrome. Measurements of autoantibodies and serum antibodies to dietary antigens in relation to zinc levels

Recurrent diarrhoea and weight loss in many adult patients with Down's syndrome (DS), initiated a search for malabsorption based on determination of serum IgG and IgA antibody levels to dietary antigens. The results were compared with measurements of autoantibodies and serum zinc levels. DS patients had increased IgG and IgA activities to gluten proteins, casein and ovalbumin compared with an age- and sex-matched group of other mentally retarded patients in the same institution. Intestinal biopsy was performed in six of the 38 patients; one had total and one partial villous atrophy. Serum zinc was significantly lower in DS patients (median 14.7 mumol/l, range 5.5-20 mumol/l) than in the controls (median 16.4 mumol/l, range 12.7-19.5 mumol/l). DS patients with increased IgA activity to gluten weighed less and had lower concentrations of zinc in serum than DS patients with normal IgA activity. Twenty-eight per cent of the DS patients had autoantibodies to the thyroid gland. Our results suggest intestinal malfunction in DS, perhaps related to a defect of immune regulation caused by reduced levels of zinc in serum.

Cell-mediated cytotoxicity in Down syndrome: impairment of allogeneic mixed lymphocyte reaction, NK and NK-like activities

Peripheral blood mononuclear cells (PBMC) from 16 non-institutionalized patients with Down syndrome (DS) were studied with various monoclonal antibodies and analysed for natural killer (NK), and NK-like activity. Lymphocyte proliferation and cytotoxic T-lymphocyte (CTL) cytotoxicity generated in mixed lymphocyte culture (MLC) were also evaluated in 11 DS patients. Phenotypic characterization of PBMC from DS subjects confirms our previous findings of high numbers of CD8+ lymphocytes and HNK-1+, and CD16+ cells. Lymphocyte proliferation and CTL cytotoxicity generated in MLC were low or absent in most patients. NK activity was low in almost all DS patients, while NK-like cytotoxicity generated in MLC was normal in the majority and did not correlate with NK activity from unstimulated PBMC.

Hirschsprung's disease. Identification of risk factors for enterocolitis

From 1975 to 1985, 80 infants and children were treated at a major pediatric hospital for Hirschsprung's disease, 19 (24%) of whom developed enterocolitis. In 9 neonates (18%) and 4 infants (29%) enterocolitis was present at diagnosis of Hirschsprung's disease, while 4 children acquired enterocolitis following a pull-through procedure. Significant risk factors for development of Hirschsprung's-associated enterocolitis (HAEC) were delay in diagnosis beyond 1 week of age and the presence of trisomy 21. HAEC did not occur more frequently in patients with long-segment aganglionosis, nor did an initial episode of HAEC confer a higher risk of recurrent enterocolitis. HAEC following a pull-through procedure was correlated with an anorectal stricture in three of four cases. Although neonates with HAEC had a low mortality rate (5%), their morbidity rate was 30% and their hospitalization was twice as long as neonates without enterocolitis.

The immunological profile of a new immunomodulatory agent, oxamisole

Oxamisole is a T-cell immunorestorative agent when administered by the oral (p.o.) route. It has little or no effect on the IgM or IgG responses to the T-dependent antigen, sheep erythrocytes (SRBC), in normal mice but augments antibody production in immunodeficient animals. Unlike the response to SRBC, the humoral immunocompetence of both normal and immunosuppressed animals sensitized with the T-independent antigen, trinitrophenyl-lipopolysaccharide (TNP-LPS) was unaffected by oxamisole. Oxamisole restored cellular immunocompetence, as evidenced by an increase in the in vitro proliferative response of normal murine splenocytes to T-cell mitogens, while decreasing B-cell mitogenic responses. This indicates that oxamisole may selectively restore T-cell function. However, oxamisole did not significantly modify the classical T-cell-mediated delayed hypersensitivity responses to either the protein antigen methylated bovine serum albumin or to the contact-sensitizing antigen oxazolone. When assayed in vitro, oxamisole enhanced macrophage chemotactic function but not phagocytic function, suggesting a potential stimulation of the reticuloendothelial system. In vivo studies failed to demonstrate any consistent significant activation of murine macrophage function following oral dosing with oxamisole.

PR 879-317A enhances in vitro immune activity of peripheral blood mononuclear cells from patients with Down syndrome

Down syndrome is associated with immune deficiencies which result in increased incidences of respiratory infections and lymphocytic leukemia. Peripheral blood mononuclear cells (PBMC) from patients with Down Syndrome were assayed in several in vitro assays following incubation in medium or various concentrations of PR 879-317A (2,3,5,6,7,8-hexahydro-2-phenyl-8,8-dimethoxyimidazo (1,2a) pyridine), a selective immunorestorative agent. PBMC of the patients, incubated in medium, exhibited significantly reduced activities in the natural killer (NK) cell, antibody-dependent cell-mediated cytotoxicity (ADCC), T-cell blastogenesis and leukocyte-inhibition factor (LIF) assays. Incubation in PR 879-317A significantly increased the NK and ADCC activities of PBMC from both patients and healthy subjects. However, the effect was much more pronounced on the patients' cells increasing their NK and ADCC activities to normal levels. Incubation in PR 879-317A augmented to normal levels the responses of patients' cells in various assessments of T-cell immunity including blastogenic responses to phytohemagglutinin and concanavalin A and production of LIF. In addition, the number of patients' cells forming spontaneous rosettes with sheep red blood cells was increased following incubation in PR 879-317A. In contrast this compound did not significantly modify the T-cell responses of cells from the healthy subjects suggesting that this compound does not affect normal T-cell function.

T-lymphocyte function in Alzheimer's disease

T-lymphocyte function in Alzheimer's disease (AS) was evaluated by means of delayed type hypersensitivity (DTH) and mitogen responsiveness using concanavalin A (Con A) and BCG vaccine as stimulators. DTH and the response to Con A was significantly lower in AD than in normal aging. The Con A response included one group in which the thymidine uptake was lower than the minimum normal response while another group was within the normal range. This subset could account for the inconsistency in previous reports of T-cell function in AD.