A new piece of the microbiota pie: Mining 'omics for DNA inversion states

In this issue of Cell Host & Microbe, Carasso et al. survey invertible DNA sites in Bacteroidales from patients with inflammatory bowel disease (IBD) and healthy control individuals. They identify complex functional interactions between Bacteroides fragilis, an invertible promoter, a capsular polysaccharide, a bacteriophage, and the human host. The establishment of 'omics approaches to characterizing genomic targets and functional roles is still required.

Impact of the Microbiota on Viral Infections

The mammalian gastrointestinal tract (GIT) hosts a diverse and highly active microbiota composed of bacteria, eukaryotes, archaea, and viruses. Studies of the GIT microbiota date back more than a century, although modern techniques, including mouse models, sequencing technology, and novel therapeutics in humans, have been foundational to our understanding of the roles of commensal microbes in health and disease. Here, we review the impacts of the GIT microbiota on viral infection, both within the GIT and systemically. GIT-associated microbes and their metabolites alter the course of viral infection through a variety of mechanisms, including direct interactions with virions, alteration of the GIT landscape, and extensive regulation of innate and adaptive immunity. Mechanistic understanding of the full breadth of interactions between the GIT microbiota and the host is still lacking in many ways but will be vital for the development of novel therapeutics for viral and nonviral diseases alike.

Horizontal Gene Transfer and CRISPR Targeting Drive Phage-Bacterial Host Interactions and Coevolution in "Pink Berry" Marine Microbial Aggregates

Bacteriophages (phages), which are viruses that infect bacteria, are the most abundant components of microbial communities and play roles in community dynamics and host evolution. However, the study of phage-host interactions is hindered by a paucity of model systems from natural environments. Here, we investigate phage-host interactions in the "pink berry" consortia, which are naturally occurring, low-diversity, macroscopic bacterial aggregates that are found in the Sippewissett Salt Marsh (Falmouth, MA, USA). We leverage metagenomic sequence data and a comparative genomics approach to identify eight compete phage genomes, infer their bacterial hosts from host-encoded clustered regularly interspaced short palindromic repeats (CRISPRs), and observe the potential evolutionary consequences of these interactions. Seven of the eight phages identified infect known pink berry symbionts, namely, Desulfofustis sp. PB-SRB1, Thiohalocapsa sp. PB-PSB1, and Rhodobacteraceae sp. A2, and they are largely divergent from known viruses. In contrast to the conserved bacterial community structure of pink berries, the distribution of these phages across aggregates is highly variable. Two phages persisted over a period of seven years with high sequence conservation, allowing us to identify gene gain and loss. Increased nucleotide variation in a conserved phage capsid gene that is commonly targeted by host CRISPR systems suggests that CRISPRs may drive phage evolution in pink berries. Finally, we identified a predicted phage lysin gene that was horizontally transferred to its bacterial host, potentially via a transposon intermediary. Taken together, our results demonstrate that pink berry consortia contain diverse and variable phages as well as provide evidence for phage-host coevolution via multiple mechanisms in a natural microbial system. IMPORTANCE Phages, which are viruses that infect bacteria, are important components of all microbial systems, in which they drive the turnover of organic matter by lysing host cells, facilitate horizontal gene transfer (HGT), and coevolve with their bacterial hosts. Bacteria resist phage infection, which is often costly or lethal, through a diversity of mechanisms. One of these mechanisms is CRISPR systems, which encode arrays of phage-derived sequences from past infections to block subsequent infection with related phages. Here, we investigate the bacteria and phage populations from a simple marine microbial community, known as "pink berries", found in salt marshes of Falmouth, Massachusetts, as a model of phage-host coevolution. We identify eight novel phages and characterize a case of putative CRISPR-driven phage evolution as well as an instance of HGT between a phage and its host, together suggesting that phages have large evolutionary impacts in a naturally occurring microbial community.

Horizontal gene transfer and CRISPR targeting drive phage-bacterial host interactions and coevolution in pink berry marine microbial aggregates

Bacteriophages (phages), viruses that infect bacteria, are the most abundant components of microbial communities and play roles in community dynamics and host evolution. The study of phage-host interactions, however, is made difficult by a paucity of model systems from natural environments and known and cultivable phage-host pairs. Here, we investigate phage-host interactions in the "pink berry" consortia, naturally-occurring, low-diversity, macroscopic aggregates of bacteria found in the Sippewissett Salt Marsh (Falmouth, MA, USA). We leverage metagenomic sequence data and a comparative genomics approach to identify eight compete phage genomes, infer their bacterial hosts from host-encoded clustered regularly interspaced short palindromic repeats (CRISPR), and observe the potential evolutionary consequences of these interactions. Seven of the eight phages identified infect the known pink berry symbionts Desulfofustis sp. PB-SRB1, Thiohalocapsa sp. PB-PSB1, and Rhodobacteraceae sp. A2, and belong to entirely novel viral taxa, except for one genome which represents the second member of the Knuthellervirus genus. We further observed increased nucleotide variation over a region of a conserved phage capsid gene that is commonly targeted by host CRISPR systems, suggesting that CRISPRs may drive phage evolution in pink berries. Finally, we identified a predicted phage lysin gene that was horizontally transferred to its bacterial host, potentially via a transposon intermediary, emphasizing the role of phages in bacterial evolution in pink berries. Taken together, our results demonstrate that pink berry consortia contain diverse and variable phages, and provide evidence for phage-host co-evolution via multiple mechanisms in a natural microbial system.

IMPORTANCE

Phages (viruses that infect bacteria) are important components of all microbial systems, where they drive the turnover of organic matter by lysing host cells, facilitate horizontal gene transfer (HGT), and co-evolve with their bacterial hosts. Bacteria resist phage infection, which is often costly or lethal, through a diversity of mechanisms. One of these mechanisms are CRISPR systems, which encode arrays of phage-derived sequences from past infections to block subsequent infection with related phages. Here, we investigate bacteria and phage populations from a simple marine microbial community known as "pink berries" found in salt marshes of Falmouth, Massachusetts, as a model of phage-host co-evolution. We identify eight novel phages, and characterize a case of putative CRISPR-driven phage evolution and an instance of HGT between phage and host, together suggesting that phages have large evolutionary impacts in a naturally-occuring microbial community.

Single-cell genomics for resolution of conserved bacterial genes and mobile genetic elements of the human intestinal microbiota using flow cytometry

As our understanding of the importance of the human microbiota in health and disease grows, so does our need to carefully resolve and delineate its genomic content. 16S rRNA gene-based analyses yield important insights into taxonomic composition, and metagenomics-based approaches reveal the functional potential of microbial communities. However, these methods generally fail to directly link genetic features, including bacterial genes and mobile genetic elements, to each other and to their source bacterial genomes. Further, they are inadequate to capture the microdiversity present within a genus, species, or strain of bacteria within these complex communities. Here, we present a method utilizing fluorescence-activated cell sorting for isolation of single bacterial cells, amplifying their genomes, screening them by 16S rRNA gene analysis, and selecting cells for genomic sequencing. We apply this method to both a cultured laboratory strain of Escherichia coli and human stool samples. Our analyses reveal the capacity of this method to provide nearly complete coverage of bacterial genomes when applied to isolates and partial genomes of bacterial species recovered from complex communities. Additionally, this method permits exploration and comparison of conserved and variable genomic features between individual cells. We generate assemblies of novel genomes within the Ruminococcaceae family and the Holdemanella genus by combining several 16S rRNA gene-matched single cells, and report novel prophages and conjugative transposons for both Bifidobacterium and Ruminococcaceae. Thus, we demonstrate an approach for flow cytometric separation and sequencing of single bacterial cells from the human microbiota, which yields a variety of critical insights into both the functional potential of individual microbes and the variation among those microbes. This method definitively links a variety of conserved and mobile genomic features, and can be extended to further resolve diverse elements present in the human microbiota.

Enteric viruses seize their immunomodulatory niche

Enteric eukaryotic viruses are increasingly recognized as non-pathogenic, immunomodulatory participants in the healthy intestinal microbiota. In this issue of Cell Host & Microbe, Dallari et al. (2021) use a single virus infection approach to reveal both generalized viral immune responses and numerous unique, virus-specific response profiles.

Infection with Bacteroides Phage BV01 Alters the Host Transcriptome and Bile Acid Metabolism in a Common Human Gut Microbe

Gut-associated phages are hypothesized to alter the abundance and activity of their bacterial hosts, contributing to human health and disease. Although temperate phages constitute a significant fraction of the gut virome, the effects of lysogenic infection are underexplored. We report that the temperate phage, Bacteroides phage BV01, broadly alters its host's transcriptome, the prominent human gut symbiont Bacteroides vulgatus. This alteration occurs through phage-induced repression of a tryptophan-rich sensory protein (TspO) and represses bile acid deconjugation. Because microbially modified bile acids are important signals for the mammalian host, this is a mechanism by which a phage may influence mammalian phenotypes. Furthermore, BV01 and its relatives in the proposed phage family Salyersviridae are ubiquitous in human gut metagenomes, infecting a broad range of Bacteroides hosts. These results demonstrate the complexity of phage-bacteria-mammal relationships and emphasize a need to better understand the role of temperate phages in the gut microbiome.

Allergenicity of bony and cartilaginous fish - molecular and immunological properties

Allergy to bony fish is common and probably increasing world-wide. The major heat-stable pan-fish allergen, parvalbumin (PV), has been identified and characterized for numerous fish species. In contrast, there are very few reports of allergic reactions to cartilaginous fish despite widespread consumption. The molecular basis for this seemingly low clinical cross-reactivity between these two fish groups has not been elucidated. PV consists of two distinct protein lineages, α and β. The α-lineage of this protein is predominant in muscle tissue of cartilaginous fish (Chondrichthyes), while β-PV is abundant in muscle tissue of bony fish (Osteichthyes). The low incidence of allergic reactions to ingested rays and sharks is likely due to the lack of molecular similarity, resulting in reduced immunological cross-reactivity between the two PV lineages. Structurally and physiologically, both protein lineages are very similar; however, the amino acid homology is very low with 47-54%. Furthermore, PV from ancient fish species such as the coelacanth demonstrates 62% sequence homology to leopard shark α-PV and 70% to carp β-PV. This indicates the extent of conservation of the PV isoforms lineages across millennia. This review highlights prevalence data on fish allergy and sensitization to fish, and details the molecular diversity of the two protein lineages of the major fish allergen PV among different fish groups, emphasizing the immunological and clinical differences in allergenicity.

Baked egg food challenges - clinical utility of skin test to baked egg and ovomucoid in children with egg allergy

BACKGROUND

Many children with IgE-mediated egg allergy can tolerate products containing extensively heated (baked) egg. Aside from food challenge, there are no tests which reliably predict tolerance to baked egg in egg-allergic individuals.

OBJECTIVES

To determine if skin prick test (SPT) to baked egg (muffin) and ovomucoid can predict the outcome of baked egg challenges in egg allergic patients.

METHODS

In this prospective study, children with a recent history of immediate allergic reactions to egg [and corroborative positive SPT or serum-specific IgE (ssIgE) to egg] or those with SPT/ssIgE > 95% PPV for egg allergy were invited to undergo an open standardized baked egg (muffin) challenge. SPT to egg white, ovomucoid, and fresh muffin were performed immediately prior to challenge.

RESULTS

One hundred and forty-three egg allergic children underwent baked egg challenge and of these, 90 (63%) tolerated 1 g of egg protein in a baked muffin. Of the 53 positive challenges, eight (15%) had respiratory and/or cardiovascular symptoms. The median SPT diameters in positive challenges compared with negative challenges were baked muffin - 6.0 mm/4.0 mm and ovomucoid 7.5 mm/5.0 mm respectively. Receiver operating characteristic (ROC) curves were generated for SPT to baked egg and ovomucoid. The area under the curve was 0.68 for baked egg, and 0.67 for ovomucoid. A muffin SPT of < 2 mm had a negative predictive value of 88% and an ovomucoid SPT ≥ 11 mm had a positive predictive value of 100%.

CONCLUSIONS AND CLINICAL RELEVANCE

A SPT of < 2 mm to muffin had a high negative predictive value to baked egg challenge. Ovomucoid SPT ≥ 11 mm was very likely to predict a reaction to baked egg. In these children, deferring the challenge would be appropriate.

Food allergy: is strict avoidance the only answer?

It is an immunological paradigm that avoidance of food allergen may reduce the risk or prevent immunological reactions and conversely that a greater exposure increases the magnitude of the immune response. Consequently, food allergen avoidance has been recommended to reduce the risk of sensitization in infants and to prevent clinical reactions in children with positive skin prick tests (SPT). In the latter setting, it is hoped that avoidance may either promote or at least not retard the development of tolerance. Animal studies, however, have demonstrated that tolerance to food allergens may be induced by either large (high zone tolerance) or small (low zone tolerance) doses, whereas doses in between may actually stimulate immune responses. In this review, we discuss whether strict allergen avoidance is always the most appropriate strategy for preventing or managing IgE-mediated food allergy.

Frequency analysis of air and skin temperature in neonates in servo-controlled incubators

OBJECTIVE

To test a new system designed for digital recording of skin and air temperature, thereby allowing analysis of cyclic changes in temperature in neonates in servo-controlled incubators.

METHODS

Analysis of cyclic changes of serial skin and air temperature in asymptomatic infants in servo-controlled incubators adjusting heat output to the patient's temperature.

RESULTS

In nine asymptomatic neonates ranging from 25 to 40 weeks of gestational age, analysis showed peaks of coherence (squared correlation) between skin and air temperature measurements at periods ranging between 1.5 and 3 h.

CONCLUSION

We have established a new system to study cyclic changes in skin and air temperature in neonates in servo-controlled incubators. The analysis of this pilot study suggests that the most important changes in skin and air temperature in asymptomatic neonates occur at a periodicity of 1.5 to 3 h, which is similar to that previously described for neonatal temperature. Additional data are required to determine whether this new system may be useful in neonatal care.

Osteomyelitis and pyogenic sacroiliitis: A difficult diagnosis

Pyogenic sacroiliitis is an uncommon infection often diagnosed late because of poor localization of symptoms and inadequate physical examination. We describe a 12-year-old girl whose osteomyelitis and pyogenic sacroiliitis was initially misdiagnosed and discuss examination, investigation and management of the condition. This case highlights the importance of thorough physical examination and the consideration of septic arthritis in an unusual joint.

Proposal for including what is valuable to ecosystems in environmental assessments

Assessment scientists and managers depend on social values to identify the goals that will be used to guide environmental assessments. These goals are commonly identified by examining the vested interests of the various social groups that are stakeholders in a region. However, knowledge about what people value represents only part of the information needed to identify comprehensive assessment goals for environmental systems that include both economic and ecological components and processes. All parties also need to understand what is valuable to ecosystems because that determines the ecological patterns and processes that prevail in the long run. The competition among alternate system designs for available energy determines the viability of the choices that people make for their environment. Ecosystems that prevail in competition use the process of self-organization to create system designs that maximize the use of ever-changing sources of available energy. The efficacy of ecosystem designs can be evaluated using the maximum empower principle, which states that ecosystems evolve toward designs that maximize empower (energy use per unit time). Energy is an accounting quantity that normalizes the different kinds of energy developed in a system so that they may be compared. The counter-intuitive and sometimes controversial results that come from energy analyses are illustrated by examining three environmental problems on the interface between ecology and economics. A process for identifying and using social and ecosystem values to guide environmental assessments is proposed using a conceptual energy systems model that shows how these processes might interact within a region. The probability of realizing a given change in system empower production is suggested as a decision criterion that can be used by managers to evaluate the efficacy of alternatives.

Limits of viability: dilemmas, decisions, and decision makers

Decision-making about treatments for neonates at the threshold of viability is a complex process that must involve physicians, other health-care professionals, and families. Parents and families bring personal, ideological, cultural, and religious beliefs into their relationship with health-care professionals that have the potential to conflict with professional perceptions of good medical care and the interests of the patient. Neonatologists often find themselves criticized for overtreatment of these extremely premature infants. Yet, from the perspective of the health-care provider, perceived obligations in the face of an uncertain outcome, parental wishes as well as perceptions about legal mandates are often cited as the reasons for the provision of such extraordinary care. Recent reductions in perinatal mortality for premature infants born at the cusp of viability, in conjunction with emerging data on the substantial short- and long-term morbidities experienced by infants born between 23-25 weeks' gestation, have engendered a serious debate about professional and parental obligations in the face of extreme uncertainty. The fundamental questions are who ought to be permitted, under the present circumstances of rapidly evolving technologies and innovative therapies, to decide the best interests of the child, and how to achieve consensus regarding treatment goals when the outcome is uncertain and there are divergent views with regard to the infant's best interests. As survival for these infants increases and morbidity remains a significant likelihood, physicians must be cognizant of the power of their technology to impose undesired burdens on these infants. A reasonable, and reasoned, approach for these vulnerable infants requires collaborative decision making incorporating professional recommendations, with an openness, trust and willingness to work with parents to ascertain the best interests of an individual infant. Understanding of and respect for the differing views of the moral obligations of perinatal specialists and families can aid neonatal professionals in resolving interdisciplinary and physician-family conflicts as well as facilitating resolution of neonatal ethical dilemmas.

Detection of substance P and its receptor in human fetal microglia

Substance P, the most abundant neurokinin in the CNS, is a major modulator of the immune system. We have examined the gene expression of substance P and its receptor in human fetal brain microglia. Using reverse transcription-polymerase chain reaction and Southern blotting assay, the four isoforms of preprotachykinin-A gene transcripts (alpha, beta, gamma and delta) were detected in the microglia. The human fetal microglia produced significantly higher levels of endogenous substance P protein (640-850 pg/10(6) cells) than did human peripheral blood monocyte-derived macrophages (25-50 pg/10(6) cells), as determined by an enzyme immunoassay. Using immunohistochemical staining with an anti-substance P antibody, cell membrane substance P immunoreactivity was observed. In addition, we identified the presence of messenger RNA for neurokinin-1 receptor, a primary receptor for substance P in human fetal microglia.From these data, we propose that substance P and its receptor are biologically involved in regulating the functions of microglia, and potentially play an important role in host defense of the central nervous system.

Immune response to infection with Mycobacterium ulcerans

Mycobacterium ulcerans is a slow-growing, acid-fast bacillus that causes chronic necrotizing skin ulcers known as Buruli ulcers. Previously reported information on immunity to this mycobacterium is limited. We examined immune responses to M. ulcerans and M. bovis BCG in patients with M. ulcerans disease and in 20 healthy control subjects (10 tuberculin test positive and 10 tuberculin test negative). Cell-mediated immunity was assessed by stimulating peripheral blood mononuclear cells (PBMC) with whole mycobacteria and then measuring PBMC proliferation and the production of gamma interferon (IFN-gamma). Humoral immunity was assessed by immunoblotting. PBMC from all subjects showed significantly greater proliferation and IFN-gamma production in response to stimulation with living mycobacteria compared with killed cells. However, PBMC from subjects with past or current M. ulcerans disease showed significantly reduced proliferation and production of IFN-gamma in response to stimulation with live M. ulcerans or M. bovis than PBMC from healthy, tuberculin test-positive subjects (P < 0.001) and showed results in these assays comparable to those of tuberculin test-negative subjects (P > 0.2). Serum from 9 of 11 patients with M. ulcerans disease, but no control subject, contained antibodies to M. ulcerans. The results indicate that patients with M. ulcerans infection mount an immune response to M. ulcerans as evidenced by antibody production, but they demonstrate profound systemic T-cell anergy to mycobacterial antigens. These findings may explain some of the distinct clinical and pathological features of M. ulcerans-induced disease.

Human alveolar macrophages induce functional inactivation in antigen-specific CD4 T cells

BACKGROUND

Alveolar macrophages (AMCs) are the most abundant phagocytic cells in the lung, but they present antigen poorly to T cells.

OBJECTIVES

The objectives of our studies were to more clearly define the mechanisms by which AMCs present antigen to T cells and to determine whether AMCs actively inhibit T-cell activation.

METHODS

We studied purified human CD4 T cells and compared the capacity of allogeneic AMCs and peripheral blood monocytes to induce T-cell proliferation and cytokine production.

RESULTS

We previously demonstrated that human AMCs fail to upregulate expression of B7-1 and B7-2 on stimulation with IFN-gamma. We now demonstrate that AMCs actively induce T-cell unresponsiveness (functional inactivation) in an antigen-specific manner and reduce the capacity of CD4 T cells to respond on secondary stimulation. The induction of unresponsiveness was reversed by the addition of CD28 costimulation or IL-2. However, interruption of Fas/Fas ligand interactions or of B7/CTLA-4 interactions did not prevent unresponsiveness, indicating that neither CTLA-4 triggering nor Fas-induced apoptosis was involved in the induction of T-cell unresponsiveness.

CONCLUSIONS

These studies indicate that AMCs actively tolerize CD4 T cells in an antigen-specific fashion. We propose that AMCs mediate a form of immune privilege in the lungs that effectively limits immune responses in the pulmonary compartment but has little effect on systemic immunity.

Measurement of cytokine secretion, intracellular protein expression, and mRNA in resting and stimulated peripheral blood mononuclear cells

Quantitation of cytokine production is a valuable adjunct to standard immunologic assays in defining several pathologic processes. Nevertheless, there is little agreement about which tissues should be assayed, which type of assay should be performed, and which stimulation protocol should be used. As these types of assays enter the clinical arena, there is need for standardization. There is also a need to maximize the amount of information which may be derived from a single sample. We compared secreted interleukin 4 (IL-4), IL-2, IL-6, tumor necrosis factor alpha (TNF-alpha), and gamma interferon proteins as measured by enzyme-linked immunosorbent assay with intracellular cytokine production (IL-2 and gamma interferon) as detected by flow cytometry and quantitative competitive PCR for IL-2, IL-4, TNF-alpha, and gamma interferon mRNA and cDNA. Results from unstimulated cells and cells stimulated with phorbol myristate acetate, phytohemagglutinin, and phorbol myristate acetate plus phytohemagglutin were compared. All three methodologies detected significant stimulation of cytokine production. The combination of phytohemagglutinin and phorbol myristate acetate was overall the most-potent stimulus.

Effect of neonatal test environment on recording transient-evoked otoacoustic emissions

OBJECTIVE

To examine the effect of test environment on recording transient-evoked otoacoustic emissions (TEOAE) in neonates.

METHODS

Thirty-two infants from the newborn nursery (NBN) who passed a screening auditory brainstem response (SABR) test and were at least 34 weeks' postconceptional age were studied. One ear of each newborn was tested using TEOAE in 5 different test environments: open bassinet in the NBN (E1), working isolet located in the NBN (E2), nonfunctioning isolet in the NBN (E3), nonfunctioning isolet in a quiet room off the NBN (E4), and open bassinet in a quiet room (E5). The number of high noise samples (HNS), the test duration (in seconds), the signal-to-noise ratio (SNR; in dB) measured at bandwidths centered at 1.6, 2.4, 3.2, and 4.0 kHz, and the percentage of neonates with a fail screening outcome based on a common pass-fail screening criteria were compared in the 5 test environments.

RESULTS

There were statistically significant differences in the number of HNS accumulated in the 5 test environments (F = 6.79). The use of a nonfunctioning isolet in both the NBN and within a room off the NBN (E3 and E4, respectively) resulted in significantly fewer HNS than when TEOAEs were recorded in the other 3 test environments (E1, E2, and E5). Mean test duration was significantly different among the 5 locations (F = 6. 53). Posthoc analyses revealed that test time in E3 and E4 was significantly shorter than in E1 and E2. The percentage of newborns with a fail (</=3 dB SNR at 2.4, 3.2, and 4.0 kHz) outcome was lowest in E3 (6.3%) and the same in E1 and E4 (12.5%). A high percentage of infants received a fail outcome when tested in both the working isolet and in the open bassinet in a room off the nursery (21.8% and 25%, respectively). SNR (in dB) for bandwidths centered at 1.6, 2.4, and 3.2 kHz was negatively correlated with the HNS in the working isolet. SNR (in dB) at 4.0 kHz was negatively correlated with the HNS when TEOAEs were recorded in the open bassinet in a room adjacent to the NBN. The number of HNS was correlated with overall test time in each environment.

CONCLUSIONS

Test environments typically used for newborn hearing screening can influence the recording of TEOAEs. Performing the TEOAE test with the neonate placed in a nonfunctioning isolet located in either the NBN or in a room off of the NBN resulted in the most desirable outcomes (shortest test times, fewest HNS, highest SNR (in dB), and fewest fail outcomes).

Multisite comparison of CD4 and CD8 T-lymphocyte counting by single- versus multiple-platform methodologies: evaluation of Beckman Coulter flow-count fluorospheres and the tetraONE system. The NIAID DAIDS New Technologies Evaluation Group

New analytic methods that permit absolute CD4 and CD8 T-cell determinations to be performed entirely on the flow cytometer have the potential for improving assay precision and accuracy. In a multisite trial, we compared two different single-platform assay methods with a predicate two-color assay in which the absolute lymphocyte count was derived by conventional hematology. A two-color method employing lymphocyte light scatter gating and Beckman Coulter Flow-Count fluorospheres for absolute counting produced within-laboratory precision equivalent to that of the two-color predicate method, as measured by coefficient of variation of replicate measurements. The fully automated Beckman Coulter tetraONE System four-color assay employing CD45 lymphocyte gating, automated analysis, and absolute counting by fluorospheres resulted in a small but significant improvement in the within-laboratory precision of CD4 and CD8 cell counts and percentages suggesting that the CD45 lymphocyte gating and automated analysis might have contributed to the improved performance. Both the two-color method employing Flow-Count fluorospheres and the four-color tetraONE System provided significant and substantial improvements in between-laboratory precision of absolute counts. In some laboratories, absolute counts obtained by the single-platform methods showed small but consistent differences relative to the predicate method. Comparison of each laboratory's absolute counts with the five-laboratory median value suggested that these differences resulted from a bias in the absolute lymphocyte count obtained from the hematology instrument in some laboratories. These results demonstrate the potential for single-platform assay methods to improve within-laboratory and between-laboratory precision of CD4 and CD8 T-cell determinations compared with conventional assay methods.

T-lymphocyte subsets in HIV-infected and high-risk HIV-uninfected adolescents: retention of naive T lymphocytes in HIV-infected adolescents. The Adolescent Medicine HIV/AIDS Research Network

BACKGROUND

The capacity of the immune system of adolescents to generate and repopulate naive and memory cell populations under conditions of normal homeostasis and human immunodeficiency virus (HIV) infection is largely unknown.

OBJECTIVE

To assess lymphocyte subsets in HIV-infected and high-risk HIV-negative adolescents.

DESIGN

The Reaching for Excellence in Adolescent Care and Health Project of the Adolescent Medicine HIV/AIDS Research Network recruits a cohort of HIV-infected and high-risk HIV-uninfected adolescents, aged 13 to 18 years 364 days, into a study of biomedical and behavioral features of HIV infection as seen in the context of full availability of primary care and HIV-related consultative services. Lymphocyte phenotypes were determined using standard 3-color flow cytometry.

SETTING

The Reaching for Excellence in Adolescent Care and Health Project is carried out at 16 clinical sites in 14 urban areas.

PARTICIPANTS

T-lymphocyte subsets are reported in 192 HIV-positive and 78 HIV-negative youths.

RESULTS

For HIV-positive subjects, the total CD4+ cell count and the percentage of CD4+ cells are decreased when compared with those of the HIV-negative controls (P<.001). The reduction in total CD4+ cells reflects a loss of naive, and memory, CD4+ cells compared with HIV-negative youths. Human immunodeficiency virus-infected adolescents, many of whom have been infected recently (ie, those with CD4+ cell counts > or =0.500 x 10(9)/L [500/microL]), have a significant increase in naive CD8+ cells compared with HIV-negative youths (P<.01). There also is a significant increase in memory CD8+ cells at all strata of total CD4+ cells compared with HIV-negative youths (P<.01). The increase in naive CD8+ cells in those subjects with CD4+ cell counts of 0.500 x 10(9)/L or greater is a unique finding in this cohort.

CONCLUSIONS

This study demonstrates high levels of naive CD8+ cells in response to HIV infection in adolescents with CD4+ cell counts of 0.500 X 10(9)/L or greater. The presence of high levels of naive CD8+ cells suggests functioning thymic tissue in some adolescents infected with HIV. Furthermore, the normal level of naive CD4+ cells in adolescents with CD4+ levels of 0.500 x 10(9)/L or greater provides additional support for the concept of a more robust immune system in HIV-infected adolescents compared with HIV-infected adults. These observations suggest that the immune system of HIV-infected adolescents may be capable of better responses to neoantigens and cytotoxic T-lymphocyte responses to HIV than the immune system of infected children or adults. Human immunodeficiency virus-infected adolescents may have an immune system that is capable of reconstitution following highly active antiretroviral therapy.

Rapid method for determining the rate of DNA synthesis and cellular proliferation

A new method has been developed for determination of DNA synthesis during cell proliferation. The method is based on the metabolism of [U-(13)C(6)]glucose to deoxyribose (DR) and then incorporation of [U-(13)C(5)]DR into newly synthesized DNA. Extracted cellular DNA is subjected to HCl hydrolysis (2 h at 100 degrees C), which converts DR into levulinic acid. The (13)C enrichment in DR is determined in the trimethylsilyl derivative of levulinate using gas chromatography-mass spectrometry. The method is rapid and sensitive. It can precisely determine (13)C enrichment below 1 at.% excess in as little as 4 ng DNA. We have used this method to determine the rate of cell proliferation in vitro and the level of DR in a given amount of DNA. The current approach has significant advantages over previously described methods and overcomes several difficulties related to the determination of DNA synthesis both in vivo and in vitro.

C-C chemokine profile of cord blood mononuclear cells: selective defect in RANTES production

Three C-C chemokines inhibit human immunodeficiency virus (HIV) entry into macrophages: macrophage inflammatory protein-1alpha (MIP-1alpha), MIP-1beta, and regulated-upon activation, normal T-cell expressed and secreted (RANTES). We studied the ability of placental cord blood mononuclear cells (CBMC) to secrete these C-C chemokines in comparison to adult blood mononuclear cells (ABMC). CBMC had diminished ability to secrete RANTES, as determined by enzyme-linked immunosorbent assay. Secretion of MIP-1alpha and MIP-1beta were similar in CBMC and ABMC. Whereas MIP-1alpha and MIP-1beta secretion were comparable in monocytes and lymphocytes, RANTES was secreted primarily by lymphocytes. Flow cytometric analysis of RANTES expression showed diminished intracellular RANTES expression in cord blood lymphocytes (CBL) compared to adult (peripheral) blood lymphocytes (ABL). A subset analysis of RANTES-producing CBL and ABL demonstrated that RANTES was produced predominantly by CD8+/CD45RO+ cells. CBL had a reduced proportion of CD8+/CD45RO+ cells compared with ABL, which may account for the diminished RANTES secretion by CBMC. These results may be relevant to the pathogenesis of perinatal HIV infection. (Blood. 2000;95:715-718)

Furosemide for symptomatic patent ductus arteriosus in indomethacin-treated infants

BACKGROUND

Inhibition of prostaglandin synthesis mediates closure of the ductus arteriosus and renal side effects after indomethacin administration. Because furosemide increases prostaglandin production, it could potentially help prevent indomethacin-related toxicity but also decrease ductal response to indomethacin.

OBJECTIVES

The primary objectives of this review were to assess (1) whether furosemide affects the incidence of failure of ductal closure after indomethacin and that of indomethacin-related toxicity and (2) the effect of furosemide on mid-term and long-term outcome. The secondary objective was to determine whether the effect of furosemide on renal function and water balance depends on prior extracellular volume (assessed by blood urea nitrogen [BUN]/creatinine ratio).

SEARCH STRATEGY

We searched electronic databases (Medline, Embase and Cochrane) and selected abstract books, without language restriction.

SELECTION CRITERIA

We selected studies with (1) random allocation to either indomethacin alone or indomethacin and furosemide and (2) analysis of either short-term risk-benefit ratio of furosemide, mid- or long-term outcome, or the relationship between extracellular volume at study entry and changes in renal function.

DATA COLLECTION AND ANALYSIS

We assessed studies for possible bias and for quality of assessment of ductal patency. We assessed categorical variables using relative risk and absolute risk reduction. We assessed the effects of furosemide on renal function and fluid balance by comparing changes from baseline in the treatment group with those in controls. Subsets were determined a priori based on BUN/creatinine ratio at study entry.

MAIN RESULTS

All 3 studies fulfilling the entry criteria had limitations, including possible or definite bias. There was substantial heterogeneity among studies. Furosemide administration did not significantly increase the risk of failure of ductal closure; however, sample size was insufficient to rule out even a 31% increase. In the subset with initial BUN/creatinine ratio > 20 mg/mg, 2 of 18 patients receiving furosemide could not complete a 3-dose course of indomethacin because of toxicity. Minimal or no information was available about any of the other main outcome variables. Furosemide increased urine output regardless of the initial BUN/creatinine ratio, leading to a 5% weight loss during a 3-dose course, an undesired effect in patients with initial BUN/creatinine ratio > 20 mg/mg. Furosemide increased creatinine clearance only in patients with initial BUN/creatinine ratio <20 mg/mg.

REVIEWER'S CONCLUSIONS

There is not enough evidence to support the administration of furosemide to premature infants treated with indomethacin for symptomatic patent ductus arteriosus. Furosemide appears to be contraindicated in the presence of dehydration in those infants.

Human immunodeficiency virus infection of human placental cord blood CD34+AC133+ stem cells and their progeny

The AC133 is a novel antigen selectively expressed on primitive CD34bright stem cells and is a valuable marker for the selection of long-term culture-initiating cells (LTC-ICs) and severe combined immunodeficiency (SCID)-repopulating cells. Human placental cord blood (HPCB) is a rich source of CD34+AC133+ cells. Since AC133 antibody is likely to be used as an alternative to CD34 for the selection of stem cells in transplant and gene therapy situations, we examined the susceptibility of HPCB-isolated CD34+AC133+ stem cells to infection with free and cell-associated HIV-1 in vitro. Freshly isolated HPCB CD34+AC133+ stem cells were not susceptible to HIV-1 infection as determined by PCR and reverse transcriptase assays. Inoculation with HIV-1 did not affect the viability and clonogenic ability of HPCB CD34+AC133+ cells. Although the highly purified HPCB CD34+AC133+ stem cells contained mRNA for CD4 and CXCR4 receptors, CD4 and CXCR4 proteins were not expressed on these cells. Similarly, CCR5 protein, the major macrophage-tropic HIV-1 coreceptor, was not expressed in freshly isolated HPCB CD34+AC133+ stem cells, although the transcript for CCR5 was identified in these cells. Expression of CD4, CXCR4, and CCR5 receptor proteins on the progeny derived from HPCB CD34+AC133+ stem cells was detected and correlated with susceptibility to HIV-1 infection in vitro. These findings suggest that freshly isolated HPCB CD34+AC133+ stem cells are not susceptible to HIV-1 infection and may not be a viral reservoir. These data have important implications for the use of AC133 antibody as a means of enriching for primitive hematopoietic stem cells from placental cord blood and in the design of stem cell or progenitor cell-based gene therapeutic strategies for perinatal HIV-1 infection.

Cutaneous lymphocyte-associated antigen expression in children with atopic dermatitis and non-atopic healthy children

Cutaneous lymphocyte-associated antigen (CLA) is a cell surface glycoprotein which has been implicated in the homing of lymphocytes to cutaneous sites. It is postulated to play an important role in T-cell migration to skin in atopic dermatitis; however, the expression of CLA in both normal children and children with atopic dermatitis has not been extensively studied. If CLA expression on T cells were important in the traffic of lymphocytes to atopic dermatitis skin lesions, it might be expected that the proportion of CLA+ T cells in unstimulated peripheral blood from children with atopic dermatitis would be elevated. We have examined the proportion of CLA+ T cells in children with atopic dermatitis and non-atopic age-matched controls. The proportion of CLA+ T cells in non-atopic children was highly associated with and increased with increasing age (r = 0.88, p < 0.001). There was no difference between the proportion of T cells expressing CLA in the unstimulated peripheral blood mononuclear cells from children with severe (p = 0.18) or with mild/moderate (p = 0.3) atopic dermatitis and age-matched non-atopic controls. Despite this, children with atopic dermatitis did show evidence of perturbation of CLA expression, as unlike the non-atopic children the proportion of CLA+ T cells in the atopic children did not correlate with age. These findings suggest that while CLA expression may play a role in atopic dermatitis, other as yet undefined surface markers are likely to principally determine the migration of T cells to skin in atopic dermatitis.

Decreased superoxide production, degranulation, tumor necrosis factor alpha secretion, and CD11b/CD18 receptor expression by adherent monocytes from preterm infants

Preterm infants have an increased incidence of infection, which is principally due to deficiencies in neonatal host defense mechanisms. Monocyte adherence is important in localizing cells at sites of infection and is associated with enhanced antimicrobial functions. We isolated cord blood monocytes from preterm and full-term infants to study their adhesion and immune functions, including superoxide (O2-) generation, degranulation, and cytokine secretion and their adhesion receptors. O2- production and degranulation were significantly diminished, by 28 and 37%, respectively, in adherent monocytes from preterm infants compared to full-term infants (P < 0. 05); however, these differences were not seen in freshly isolated cells. We also observed a significant decrease of 35% in tumor necrosis factor alpha secretion by lipopolysaccharide-stimulated adherent monocytes from preterm infants compared to full-term infants (P < 0.05); however, this difference was not observed in interleukin-1beta or interleukin-6 production by the monocytes. The cell surface expression of the CD11b/CD18 adhesion receptor subunits was significantly decreased (by 60 and 52%, respectively) in monocytes from preterm infants compared to full-term infants (P < 0. 01). The cascade of the immune response to infection involves monocyte upregulation and adherence via CD11b/CD18 receptors followed by cell activation and the release of cytokines and bactericidal products. We speculate that monocyte adherence factors may be important in the modulation of immune responses in preterm infants.

Pooled human immunoglobulin inhibits IL-4 but not IFN-gamma or TNF-alpha secretion following in vitro stimulation of mononuclear cells with Staphylococcal superantigen

Intravenous immunoglobulin preparations have been successfully used in many disorders, where immunomodulation rather than immunoglobulin replacement has been the goal of therapy. The exact mechanisms by which immunoglobulin exerts its immunomodulatory effects are unclear. Proposed mechanisms include modification of T cell activation and alteration to cytokine production. As intravenous immunoglobulin therapy has been used in a number of disorders where superantigens are proposed to play a role in the disease pathogenesis, we have examined the effect of in vitro human pooled immunoglobulin on cytokine production from peripheral blood mononuclear cells in response to activation with the Staphylococcal superantigen Staphylococcal enterotoxin B. The authors found inhibition of secretion of interleukin 4 (IL-4) (P<0.001) but not interferon gamma (IFN-gamma) (P=0.13) or tumour necrosis factor alpha (TNF-alpha) (P=0.66) by pooled immunoglobulin at concentrations (6 g/l) which approximate the rise in serum immunoglobulin following in vivo IVIG therapy. Mononuclear cell proliferation was also inhibited by addition of pooled immunoglobulin to superantigen stimulated cultures. These effects do not relate to specific anti-staphylococcal enterotoxin B antibodies in the immunoglobulin preparation. The authors show that pooled human immunoglobulin can differentially modulate the secretion of IL-4 and IFN-gamma in response to superantigen stimulation.

Furosemide in indomethacin-treated infants--systematic review and meta-analysis

This study was designed to assess: (1) whether furosemide modifies the incidence of failure to close a symptomatic patent ductus arteriosus (PDA) in response to indomethacin in premature infants, (2) whether furosemide decreases renal and hydromineral side effects of indomethacin, and (3) whether the effects of furosemide on renal function depend on initial extracellular volume [assessed by blood urea nitrogen (BUN)/creatinine ratio]. We did a systematic review and meta-analysis of all published controlled trials assessing either ductal closure or renal function after randomized allocation to treatment with indomethacin and furosemide versus indomethacin alone. All of the three studies meeting entry criteria were small and had methodological limitations. The number of patients was too small to rule out a 10% risk increase in failure of ductal closure. After the first dose of indomethacin, patients receiving furosemide had higher urine output, fractional excretion of sodium, and osmolar clearance than controls. Among patients with initial BUN/creatinine ratio <20, those on furosemide had a higher glomerular filtration rate (GFR) than controls. Among patients with initial BUN/creatinine of 20-30, those on furosemide had a lower GFR than controls. Thus, dehydration appears to be a contraindication for furosemide administration in premature infants treated with indomethacin for symptomatic PDA. The risk-benefit ratio of administering furosemide in well-hydrated patients treated with indomethacin for symptomatic PDA could only be assessed by a large randomized clinical trial.

Intracellular interferon-gamma (IFN-gamma) production in normal children and children with atopic dermatitis

A reduction in the in vitro production of IFN-gamma has been consistently described in atopic dermatitis (AD). Whether this reduction is due to a decrease in the population of peripheral blood mononuclear cells (PBMC) producing IFN-gamma or reduced IFN-gamma production per cell, or a combination of both is not clear. We have examined the intracellular production of IFN-gamma in children with AD and in healthy non-atopic controls. As Staphylococcus aureus colonization is a feature of childhood AD, and is postulated to contribute to the cutaneous inflammation in atopic dermatitis, S. aureus and Staphylococcal enterotoxin B (SEB) were used to activate PBMC. Stimulated PBMC from subjects with AD had significantly fewer IFN-gamma-containing cells in response to SEB (P < 0.001) and S. aureus (P < 0.01) than normal non-atopic children. In addition, SEB-stimulated PBMC from children with AD had less IFN-gamma per cell than normal non-atopic children (P < 0.01). Reduction in the proportion of cells containing IFN-gamma was seen in CD4+, CD8+ and natural killer (NK) cells in PBMC from children with AD. Our findings indicate that reduced production of IFN-gamma observed in childhood AD is due to both a decrease in the number of IFN-gamma-producing cells and a reduced amount of IFN-gamma production per cell. Furthermore, we found that this defect was not confined to CD4+ T cells, suggesting a more generalized defect in IFN-gamma production in childhood AD.

Interferon-gamma upregulates CCR5 expression in cord and adult blood mononuclear phagocytes

The C-C chemokine receptors CCR5 and CCR3 are fusion coreceptors for human immunodeficiency virus (HIV) entry into macrophages. The regulation of their expression influences infectivity by HIV. We report here that interferon-gamma (IFN-gamma) a cytokine that has bidirectional effects on HIV infection of macrophages, significantly upregulated CCR5 and CCR3 cell surface expression in human mononuclear phagocytes isolated from placental cord blood and adult peripheral blood. Monocytes treated with IFN-gamma showed increased chemotaxis to the CCR5 ligands macrophage inflammatory protein-1alpha (MIP-1alpha) and MIP-1beta, confirming the functional relevance of IFN-gamma-induced CCR5 expression. However, IFN-gamma suppressed HIV entry into macrophages. Interestingly, we demonstrated that IFN-gamma inhibited cell surface expression of CD4, the major receptor for HIV. This finding may explain the suppressive effect of IFN-gamma on HIV entry into macrophages, despite its enhancing effect on the expression of CCR5 and CCR3 by these cells. In addition, IFN-gamma-induced secretion of C-C chemokines (RANTES, MIP-1alpha, and MIP-1beta) by mononuclear phagocytes may also suppress HIV entry into macrophages. These data provide further evidence for cytokine-mediated regulation of CCR5 expression and are consistent with a novel paradigm in which cytokines regulate HIV infection and leukocyte migration by reciprocal and opposing effects on the expression of CD4 and chemokine receptors.

Production of antibodies to staphylococcal superantigens in atopic dermatitis

Staphylococcal superantigens (SAG) are implicated in the inflammation of atopic dermatitis. As SAG mediated diseases may be modified by specific antibodies, the antibody response to SAG in atopic dermatitis was investigated. Immunoglobulin (Ig) G to staphylococcal enterotoxin A (SEA), staphylococcal enterotoxin B (SEB), and toxic shock syndrome toxin 1 (TSST-1) were measured by sandwich enzyme linked immunosorbent assay (ELISA) in 74 children with atopic dermatitis and 111 controls. Controls had detectable IgG to SEA, SEB, and TSST-1, which increased with age. Atopic dermatitis subjects had an increased response to SEB at 6 months to 2 years (76% v 42%) and 2 to 7 years (79% v 57%), and equivalent responses to SEA and TSST-1, compared to controls. It is suggested that increased responses to SEB relate to increased colonisation and hence exposure to superantigen producing staphylococcus in atopic dermatitis, and that inflammation of atopic dermatitis is not caused by an inability to make antibody to SAG.

Enhanced IL-4 but normal interferon-gamma production in children with isolated IgE mediated food hypersensitivity

Atopic disorders such as atopic dermatitis and asthma have been characterised by an imbalance in interferon-gamma (INF-gamma) and IL-4. Whether similar imbalances are found in atopic disorders with different clinical manifestations, such as IgE mediated immediate food hypersensitivity, is not clear. We have examined the in vitro production of INF-gamma and IL-4 in peripheral blood mononuclear cells (PBMC) following phytohaemagglutinin stimulation from children with isolated immediate IgE mediated food hypersensitivity (egg, milk, "nut"), children with moderate and severe atopic dermatitis, and normal children. Children with immediate food reactions were excluded if they had a history or evidence of atopic dermatitis or asthma. PBMC from children with IgE mediated food hypersensitivity produced significantly more IL-4 (p = 0.013) but equivalent INF-gamma (p = 0.26) compared to PBMC from control children. In contrast, PBMC from children with atopic dermatitis produced significantly less INF-gamma (p < 0.001) and more IL-4 (p < 0.008) than PBMC from normal children. In addition, there was no difference in IL-4 (p = 0.74) but significantly less INF-gamma (p < 0.001) produced by PBMC from the children with atopic dermatitis than food hypersensitivity. We demonstrate that children with IgE mediated food hypersensitivity and no other manifestation of atopic disease have enhanced IL-4 production without the defect in INF-gamma production observed in childhood AD and asthma. We postulate that isolated IL-4 enhancement promotes the development of IgE mediated hypersensitivity disorders such as food allergy, whilst the combination of defective INF-gamma and enhanced IL-4 production promotes inflammatory atopic disorders such as AD and asthma.

Development and evaluation of a chromatographic procedure for partial purification of substance P with quantitation by an enzyme immunoassay

We have developed a simple chromatographic procedure for the partial purification of substance P (SP) from acidified plasma and serum samples. We have evaluated a sensitive antigen competition enzyme immunoassay (EIA) for the quantitation of SP. The chromatographic procedure has recovery efficiencies ranging from 94.8 to 125%. The immunoreactivity of unknown amounts of purified SP subjected to the preparative procedure yielded a coefficient of variance of 9.4%. The EIA yielded reproducible standard curves having an interassay (n = 8) correlation coefficient of 0.984. The evaluation of normal adult control serum yielded a mean value of 51 pg/ml (range, 35 to 61 pg/ml). The evaluation of 3.33 x concentrates of serum-derived partially purified SP provided uncorrected SP values of 117 to 201 pg/ml, which fell within the midpoint of the three-decalog standard curve. These studies indicate that both the preparative and quantitative procedures are required for the detection of SP in plasma or serum samples collected from patients with several clinical disorders.

Immune responses in mothers of term and preterm very-low-birth-weight infants

Differences in the levels of immune cell subsets present in peripheral blood have been demonstrated based on sociodemographic factors such as age and race. Postpartal women, who are recovering from the immune changes that are concomitant with pregnancy, have lymphocyte and monocyte values that differ from other populations. A subgroup of postpartal women, mothers who deliver preterm very-low-birth-weight (VLBW) (< or = 1,500 g) infants, may have further differences in values of immune cell subsets and in immune functioning either because of hormonal factors or lifestyle changes or because of the stress they experience after their infant's birth and for the first few months of infant caretaking. This study examined anxiety, depression, and immune cell phenotypes in 30 mothers of VLBW infants and in 30 mothers of healthy term infants over the first 4 postpartal months to determine if mothers of preterm VLBW infants differed from mothers of healthy term infants in psychological and immunologic parameters. Additionally, lymphocyte proliferation and natural killer cell functional assays were performed in a subset of mothers. Mothers of VLBW infants had increased anxiety and decreased lymphocyte proliferation compared to mothers of term infants. When lymphocyte and monocyte subsets were compared over time between the two groups of mothers differences were found in CD8, CD20, CD3-/CD56+, CD14, and HLA class II Ia on monocytes. Mothers with high-fat diets had lower percentages of some monocytes (CD14), lymphocytes (CD4+/CD45RA+), and natural killer cells (CD3-/CD57+) during the first 4 postpartal months.

Caregiving to very low birthweight infants: a model of stress and immune response

Mothers of preterm, very low birthweight (< or = 1500 g; VLBW) infants experience the stress of caring for small, fragile infants at the same time that they are recovering from the relative immunosuppression of pregnancy and when many health behaviour changes (e.g., nutrition) occur which also may influence immune status. The purpose of this study was to examine changes in anxiety and depression and in health behaviors, as well as lymphocyte proliferation and natural killer cell activity in mothers of preterm, VLBW infants compared to mothers of healthy term infants. Mothers of preterm VLBW infants have decreased in vitro lymphocyte response to mitogens compared to mothers of healthy term infants over time, and this difference could not be explained by anxiety, depression, or health behaviors. However, among mothers of VLBW infants, anxiety was related to decreased lymphocyte proliferation response at 1 month postpartum. There was no relationship between maternal depression and lymphocyte proliferative response in mothers of term infants. Natural killer cell activity did not differ between the two groups of mothers, nor was there a relationship between natural killer cell activity and maternal anxiety, depression, or health behaviors. Thus, lymphocyte proliferative response to mitogens may be an important biologic market of increased stress in mothers of VLBW infants in the first couple of months postpartum.

Lymphocyte, monocyte, and natural killer cell reference ranges in postpartal women

Normative values for immune-cell subsets in postpartal women, who are recovering from the relative immunosuppression of pregnancy, have not been established. Considerable differences in normative values for subsets of immune cells have been demonstrated based on sociodemographic factors, such as age and race. In order to make accurate clinical decisions about postpartal women, comparisons with normal reference ranges are necessary. Therefore, flow cytometric data for 51 healthy women at 4 months postpartum are presented and changes over the first 4 postpartal months are documented. The levels of some lymphocyte cell subsets, such as CD4+/CD45RA+ and Ia on lymphocytes, remained stable over time. The levels of other lymphocyte cell subsets, such as CD4+/CD29+, increased over the first 4 postpartal months, while those of other cell subsets, such as CD8 and CD11b, increased between delivery and 2 months postpartum and then dropped again by the fourth postpartal month. The levels of two natural killer cell subsets (CD3-/CD16+ and CD3-/CD57+) rose from delivery until 1 month postpartum and then plateaued. Comparisons were made with reference ranges of nonpostpartal groups provided in the literature and in a study of healthy women being conducted in the same laboratory, and postpartal women were found to have lower values of CD8, CD3-/CD16+, CD4+/CD45RA+, CD20, and CD11b than those reported in the literature.

Proliferation and production of interferon-gamma (IFN-gamma) and IL-4 in response to Staphylococcus aureus and staphylococcal superantigen in childhood atopic dermatitis

We have examined the cell-mediated immunity (CMI) to Staphylococcus aureus (S. aureus) and Staphylococcal enterotoxin B (SEB) in peripheral blood mononuclear cells (PBMC) from children with atopic dermatitis (AD) and from non-atopic child controls by measurement of proliferative responses and production of the cytokines IFN-gamma and IL-4. PBMC from children with AD showed significantly higher proliferative responses to both S. aureus (P < 0.01) and SEB (P < 0.05). Despite this enhanced proliferation, production of IFN-gamma in response to S. aureus (P < 0.001) and SEB (P < 0.01) from these PBMC was significantly diminished. In contrast, PBMC from children with AD were significantly more likely to produce IL-4 in response to S. aureus (P < 0.01). These findings demonstrate in vitro heightened CMI to S. aureus in children with AD, and implicate S. aureus as a potent inflammatory stimulant. Impaired IFN-gamma production to S. aureus in vivo may result in failure to eradicate S. aureus from skin. The organism's persistence on skin would contribute to inflammation by causing continued T cell activation and release of pro-inflammatory mediators.

Cytokines released by human peripheral blood mononuclear cells inhibit the production of early and late cytomegalovirus proteins

Cytomegalovirus-infected human fibroblasts are susceptible to lysis by natural killer cells and cytotoxic T cells. The purpose of this study was to determine whether non-lytic mechanisms might also contribute to the control of cytomegalovirus infection. The appearance of cytomegalovirus proteins in infected fibroblasts was determined by flow cytometry. Infected fibroblasts incubated with peripheral blood mononuclear cells for 3 days expressed less early and late proteins than fibroblasts incubated without peripheral blood mononuclear cells. Supernatants generated by the cocultivation of peripheral blood mononuclear cells with cytomegalovirus-infected fibroblasts inhibited the production of cytomegalovirus early and late proteins. The soluble factors in supernatants which contributed to the inhibitory effect were identified as interferons alpha, beta and gamma, and tumor necrosis factors alpha and beta. The ability of supernatants to inhibit the production of cytomegalovirus early protein was mimicked by combinations of corresponding recombinant cytokines. The inhibition of cytomegalovirus protein production by cytokines produced by peripheral blood mononuclear cells may contribute to early containment of cytomegalovirus infection.

Production of T-helper cell subsets and cytokines by lymphocytes from patients with chronic mucocutaneous candidiasis

Chronic mucocutaneous candidiasis (CMC) is a heterogeneous group of disorders characterized by recurrent and persistent superficial candidal infections. Cytokine-induced dysregulation of T-helper cell function has been described in other immune-deficient states but has not been studied in CMC patients. We studied T-helper cell subsets by flow cytometry and cytokine production by stimulated lymphocytes in six CMC patients, two healthy pediatric controls, and five healthy adult controls. Peripheral blood lymphocytes were stimulated in vitro with phytohemagglutinin or Candida albicans extract, and the production of interleukin-2R (IL-2R), IL-4, IL-10, and gamma interferon in the supernatants was measured by enzyme-linked immunosorbent assay. CMC patients had a decrease in the CD29+/CD29+ cell population compared with the numbers in controls (P < 0.02). The percentage of CD4+/CD45RA+ cells was greater in patients than in controls, but the difference was not significant. There was no difference in the production of IL-10 or gamma interferon by the patient lymphocytes. CMC patients produced more IL-4 than the controls (P < 0.001), whereas the controls tended to produce more IL-2R than the patients (P = 0.19). These findings support the concept that a decrease in CD4+/CD29+ T-helper inducer cells along with T-helper cell dysregulation may lead to defective memory responses to antigens in CMC patients and a decrease in cell-mediated immunity due to inhibition of TH1 cells by increased levels of IL-4.

New perspectives on inflammation in atopic dermatitis

Recent information implicates the stimulation of T cells by Staphylococcus aureus antigens and exotoxins as a likely factor in provoking the inflammatory response in atopic dermatitis. S. aureus secrets exotoxins called superantigens, which stimulate a large proportion of T cells. In addition, protein A, a component of the cell wall of S. aureus, is a potent B cell mitogen. This understanding provides a rationale for attempting to reduce the staphylococcal skin colonization of patients with severe atopic dermatitis and correlates with the clinical observation in a number of situations of marked improvement in atopic dermatitis following antibiotic treatment.