Cell-type-specific and disease-associated expression quantitative trait loci in the human lung

Common genetic variants confer substantial risk for chronic lung diseases, including pulmonary fibrosis. Defining the genetic control of gene expression in a cell-type-specific and context-dependent manner is critical for understanding the mechanisms through which genetic variation influences complex traits and disease pathobiology. To this end, we performed single-cell RNA sequencing of lung tissue from 66 individuals with pulmonary fibrosis and 48 unaffected donors. Using a pseudobulk approach, we mapped expression quantitative trait loci (eQTLs) across 38 cell types, observing both shared and cell-type-specific regulatory effects. Furthermore, we identified disease interaction eQTLs and demonstrated that this class of associations is more likely to be cell-type-specific and linked to cellular dysregulation in pulmonary fibrosis. Finally, we connected lung disease risk variants to their regulatory targets in disease-relevant cell types. These results indicate that cellular context determines the impact of genetic variation on gene expression and implicates context-specific eQTLs as key regulators of lung homeostasis and disease.

Cell type-specific and disease-associated eQTL in the human lung

Common genetic variants confer substantial risk for chronic lung diseases, including pulmonary fibrosis (PF). Defining the genetic control of gene expression in a cell-type-specific and context-dependent manner is critical for understanding the mechanisms through which genetic variation influences complex traits and disease pathobiology. To this end, we performed single-cell RNA-sequencing of lung tissue from 67 PF and 49 unaffected donors. Employing a pseudo-bulk approach, we mapped expression quantitative trait loci (eQTL) across 38 cell types, observing both shared and cell type-specific regulatory effects. Further, we identified disease-interaction eQTL and demonstrated that this class of associations is more likely to be cell-type specific and linked to cellular dysregulation in PF. Finally, we connected PF risk variants to their regulatory targets in disease-relevant cell types. These results indicate that cellular context determines the impact of genetic variation on gene expression, and implicates context-specific eQTL as key regulators of lung homeostasis and disease.

Increased Development of Th1, Th17, and Th1.17 Cells Under T1 Polarizing Conditions in Juvenile Idiopathic Arthritis

In juvenile idiopathic arthritis (JIA) inflammatory T cells and their produced cytokines are drug targets and play a role in disease pathogenesis. Despite their clinical importance, the sources and types of inflammatory T cells involved remain unclear. T cells respond to polarizing factors to initiate types of immunity to fight infections, which include immunity types 1 (T1), 2 (T2), and 3 (T17). Polarizing factors drive CD4⁺ T cells towards T helper (Th) cell subtypes and CD8⁺ T cells towards cytotoxic T cell (Tc) subtypes. T1 and T17 polarization are associated with autoimmunity and production of the cytokines IFNγ and IL-17 respectively. We show that JIA and child healthy control (HC) peripheral blood mononuclear cells are remarkably similar, with the same frequencies of CD4⁺ and CD8⁺ naïve and memory T cell subsets, T cell proliferation, and CD4⁺ and CD8⁺ T cell subsets upon T1, T2, and T17 polarization. Yet, under T1 polarizing conditions JIA cells produced increased IFNγ and inappropriately produced IL-17. Under T17 polarizing conditions JIA T cells produced increased IL-17. Gene expression of IFNγ, IL-17, Tbet, and RORγT by quantitative PCR and RNA sequencing revealed activation of immune responses and inappropriate activation of IL-17 signaling pathways in JIA polarized T1 cells. The polarized JIA T1 cells were comprised of Th and Tc cells, with Th cells producing IFNγ (Th1), IL-17 (Th17), and both IFNγ-IL-17 (Th1.17) and Tc cells producing IFNγ (Tc1). The JIA polarized CD4⁺ T1 cells expressed both Tbet and RORγT, with higher expression of the transcription factors associated with higher frequency of IL-17 producing cells. T1 polarized naïve CD4⁺ cells from JIA also produced more IFNγ and more IL-17 than HC. We show that in JIA T1 polarization inappropriately generates Th1, Th17, and Th1.17 cells. Our data provides a tool for studying the development of heterogeneous inflammatory T cells in JIA under T1 polarizing conditions and for identifying pathogenic immune cells that are important as drug targets and diagnostic markers.

WIN site inhibition disrupts a subset of WDR5 function

WDR5 nucleates the assembly of histone-modifying complexes and acts outside this context in a range of chromatin-centric processes. WDR5 is also a prominent target for pharmacological inhibition in cancer. Small-molecule degraders of WDR5 have been described, but most drug discovery efforts center on blocking the WIN site of WDR5, an arginine binding cavity that engages MLL/SET enzymes that deposit histone H3 lysine 4 methylation (H3K4me). Therapeutic application of WIN site inhibitors is complicated by the disparate functions of WDR5, but is generally guided by two assumptions-that WIN site inhibitors disable all functions of WDR5, and that changes in H3K4me drive the transcriptional response of cancer cells to WIN site blockade. Here, we test these assumptions by comparing the impact of WIN site inhibition versus WDR5 degradation on H3K4me and transcriptional processes. We show that WIN site inhibition disables only a specific subset of WDR5 activity, and that H3K4me changes induced by WDR5 depletion do not explain accompanying transcriptional responses. These data recast WIN site inhibitors as selective loss-of-function agents, contradict H3K4me as a relevant mechanism of action for WDR5 inhibitors, and indicate distinct clinical applications of WIN site inhibitors and WDR5 degraders.

Multiple interactions of the oncoprotein transcription factor MYC with the SWI/SNF chromatin remodeler

The SNF5 subunit of the SWI/SNF chromatin remodeling complex has been shown to act as a tumor suppressor through multiple mechanisms, including impairing the ability of the oncoprotein transcription factor MYC to bind chromatin. Beyond SNF5, however, it is unknown to what extent MYC can access additional SWI/SNF subunits or how these interactions affect the ability of MYC to drive transcription, particularly in SNF5-null cancers. Here, we report that MYC interacts with multiple SWI/SNF components independent of SNF5. We show that MYC binds the pan-SWI/SNF subunit BAF155 through the BAF155 SWIRM domain, an interaction that is inhibited by the presence of SNF5. In SNF5-null cells, MYC binds with remaining SWI/SNF components to essential genes, although for a purpose that is distinct from chromatin remodeling. Analysis of MYC-SWI/SNF target genes in SNF5-null cells reveals that they are associated with core biological functions of MYC linked to protein synthesis. These data reveal that MYC can bind SWI/SNF in an SNF5-independent manner and that SNF5 modulates access of MYC to core SWI/SNF complexes. This work provides a framework in which to interrogate the influence of SWI/SNF on MYC function in cancers in which SWI/SNF or MYC are altered.

Coordinated interactions between endothelial cells and macrophages in the islet microenvironment promote β cell regeneration

Endogenous β cell regeneration could alleviate diabetes, but proliferative stimuli within the islet microenvironment are incompletely understood. We previously found that β cell recovery following hypervascularization-induced β cell loss involves interactions with endothelial cells (ECs) and macrophages (MΦs). Here we show that proliferative ECs modulate MΦ infiltration and phenotype during β cell loss, and recruited MΦs are essential for β cell recovery. Furthermore, VEGFR2 inactivation in quiescent ECs accelerates islet vascular regression during β cell recovery and leads to increased β cell proliferation without changes in MΦ phenotype or number. Transcriptome analysis of β cells, ECs, and MΦs reveals that β cell proliferation coincides with elevated expression of extracellular matrix remodeling molecules and growth factors likely driving activation of proliferative signaling pathways in β cells. Collectively, these findings suggest a new β cell regeneration paradigm whereby coordinated interactions between intra-islet MΦs, ECs, and extracellular matrix mediate β cell self-renewal.

Combinatorial Transcriptional Profiling of Mouse and Human Enteric Neurons Identifies Shared and Disparate Subtypes In Situ

BACKGROUND & AIMS

The enteric nervous system (ENS) coordinates essential intestinal functions through the concerted action of diverse enteric neurons (ENs). However, integrated molecular knowledge of EN subtypes is lacking. To compare human and mouse ENs, we transcriptionally profiled healthy ENS from adult humans and mice. We aimed to identify transcripts marking discrete neuron subtypes and visualize conserved EN subtypes for humans and mice in multiple bowel regions.

METHODS

Human myenteric ganglia and adjacent smooth muscle were isolated by laser-capture microdissection for RNA sequencing. Ganglia-specific transcriptional profiles were identified by computationally subtracting muscle gene signatures. Nuclei from mouse myenteric neurons were isolated and subjected to single-nucleus RNA sequencing, totaling more than 4 billion reads and 25,208 neurons. Neuronal subtypes were defined using mouse single-nucleus RNA sequencing data. Comparative informatics between human and mouse data sets identified shared EN subtype markers, which were visualized in situ using hybridization chain reaction.

RESULTS

Several EN subtypes in the duodenum, ileum, and colon are conserved between humans and mice based on orthologous gene expression. However, some EN subtype-specific genes from mice are expressed in completely distinct morphologically defined subtypes in humans. In mice, we identified several neuronal subtypes that stably express gene modules across all intestinal segments, with graded, regional expression of 1 or more marker genes.

CONCLUSIONS

Our combined transcriptional profiling of human myenteric ganglia and mouse EN provides a rich foundation for developing novel intestinal therapeutics. There is congruency among some EN subtypes, but we note multiple species differences that should be carefully considered when relating findings from mouse ENS research to human gastrointestinal studies.

WDR5 is a conserved regulator of protein synthesis gene expression

WDR5 is a highly-conserved nuclear protein that performs multiple scaffolding functions in the context of chromatin. WDR5 is also a promising target for pharmacological inhibition in cancer, with small molecule inhibitors of an arginine-binding pocket of WDR5 (the 'WIN' site) showing efficacy against a range of cancer cell lines in vitro. Efforts to understand WDR5, or establish the mechanism of action of WIN site inhibitors, however, are stymied by its many functions in the nucleus, and a lack of knowledge of the conserved gene networks-if any-that are under its control. Here, we have performed comparative genomic analyses to identify the conserved sites of WDR5 binding to chromatin, and the conserved genes regulated by WDR5, across a diverse panel of cancer cell lines. We show that a specific cohort of protein synthesis genes (PSGs) are invariantly bound by WDR5, demonstrate that the WIN site anchors WDR5 to chromatin at these sites, and establish that PSGs are bona fide, acute, and persistent targets of WIN site blockade. Together, these data reveal that WDR5 plays a predominant transcriptional role in biomass accumulation and provide further evidence that WIN site inhibitors act to repress gene networks linked to protein synthesis homeostasis.

The LRRC8 volume-regulated anion channel inhibitor, DCPIB, inhibits mitochondrial respiration independently of the channel

There has been a resurgence of interest in the volume-regulated anion channel (VRAC) since the recent cloning of the LRRC8A-E gene family that encodes VRAC. The channel is a heteromer comprised of LRRC8A and at least one other family member; disruption of LRRC8A expression abolishes VRAC activity. The best-in-class VRAC inhibitor, DCPIB, suffers from off-target activity toward several different channels and transporters. Considering that some anion channel inhibitors also suppress mitochondrial respiration, we systematically explored whether DCPIB inhibits respiration in wild type (WT) and LRRC8A-knockout HAP-1 and HEK-293 cells. Knockout of LRRC8A had no apparent effects on cell morphology, proliferation rate, mitochondrial content, or expression of several mitochondrial genes in HAP-1 cells. Addition of 10 µM DCPIB, a concentration typically used to inhibit VRAC, suppressed basal and ATP-linked respiration in part through uncoupling the inner mitochondrial membrane (IMM) proton gradient and membrane potential. Additionally, DCPIB inhibits the activity of complex I, II, and III of the electron transport chain (ETC). Surprisingly, the effects of DCPIB on mitochondrial function are also observed in HAP-1 and HEK-293 cells which lack LRRC8A expression. Finally, we demonstrate that DCPIB activates ATP-inhibitable potassium channels comprised of heterologously expressed Kir6.2 and SUR1 subunits. These data indicate that DCPIB suppresses mitochondrial respiration and ATP production by dissipating the mitochondrial membrane potential and inhibiting complexes I-III of the ETC. They further justify the need for the development of sharper pharmacological tools for evaluating the integrative physiology and therapeutic potential of VRAC in human diseases.

Novel kidney dissociation protocol and image-based flow cytometry facilitate improved analysis of injured proximal tubules

Flow cytometry studies on injured kidney tubules are complicated by the low yield of nucleated single cells. Furthermore, cell-specific responses such as cell cycle dynamics in vivo have conventionally relied on indirect immunohistochemistry and proximal tubule markers that may be downregulated in injury. Here, we report a new tissue dissociation protocol for the kidney with an early fixation step that greatly enhances the yield of single cells. Genetic labeling of the proximal tubule with either mT/mG "tomato" or R26Fucci2aR (Fucci) cell cycle reporter mice allows us to follow proximal tubule-specific changes in cell cycle after renal injury. Image-based flow cytometry (FlowSight) enables gating of the cell cycle and concurrent visualization of the cells with bright field and fluorescence. We used the Fucci mouse in conjunction with FlowSight to identify a discrete polyploid population in proximal tubules after aristolochic acid injury. The tissue dissociation protocol in conjunction with genetic labeling and image-based flow cytometry is a tool that can improve our understanding of any discrete cell population after injury.

Ectonucleoside Triphosphate Diphosphohydrolase-3 Antibody Targets Adult Human Pancreatic β Cells for In Vitro and In Vivo Analysis

Identification of cell-surface markers specific to human pancreatic β cells would allow in vivo analysis and imaging. Here we introduce a biomarker, ectonucleoside triphosphate diphosphohydrolase-3 (NTPDase3), that is expressed on the cell surface of essentially all adult human β cells, including those from individuals with type 1 or type 2 diabetes. NTPDase3 is expressed dynamically during postnatal human pancreas development, appearing first in acinar cells at birth, but several months later its expression declines in acinar cells while concurrently emerging in islet β cells. Given its specificity and membrane localization, we utilized an NTPDase3 antibody for purification of live human β cells as confirmed by transcriptional profiling, and, in addition, for in vivo imaging of transplanted human β cells. Thus, NTPDase3 is a cell-surface biomarker of adult human β cells, and the antibody directed to this protein should be a useful new reagent for β cell sorting, in vivo imaging, and targeting.

Alternative splicing of ALCAM enables tunable regulation of cell-cell adhesion through differential proteolysis

While many adhesion receptors are known to influence tumor progression, the mechanisms by which they dynamically regulate cell-cell adhesion remain elusive. We previously identified Activated Leukocyte Cell Adhesion Molecule (ALCAM) as a clinically relevant driver of metastasis and hypothesized that a tunable mechanism of ectodomain shedding regulates its contribution to dissemination. To test this hypothesis, we examined an under-explored ALCAM splice variant (ALCAM-Iso2) and demonstrated that loss of the membrane-proximal region of ALCAM (exon 13) increased metastasis four-fold. Mechanistic studies identified a novel MMP14-dependent membrane distal cleavage site in ALCAM-Iso2, which mediated a ten-fold increase in shedding, thereby decreasing cellular cohesion. Importantly, the loss of cohesion is not limited to the cell capable of shedding because the released extracellular domain diminished cohesion of non-shedding cells through disruption of ALCAM-ALCAM interactions. ALCAM-Iso2-dominated expression in bladder cancer tissue, compared to normal bladder, further emphasizes that ALCAM alternative splicing may contribute to clinical disease progression. The requirement for both the loss of exon 13 and the gain of metalloprotease activity suggests that ALCAM shedding and concomitant regulation of tumor cell adhesion is a locally tunable process.

Obesity Alters B Cell and Macrophage Populations in Brown Adipose Tissue

OBJECTIVE

The prevalence of obesity continues to rise, and it is understood that regulation of white adipose tissue (WAT) function is important to systemic metabolic homeostasis. Immune cells play a central role in the maintenance of WAT, and their compositions change in number and inflammatory phenotype with the progression of obesity. Because of its energy-burning capabilities, brown adipose tissue (BAT) has become a focus of obesity research. Although novel studies have focused on the function of brown adipocytes in thermogenesis, the tissue as a whole has not been immunologically characterized.

METHODS

BAT immune cell populations were analyzed by flow cytometry and immunohistochemistry in mice with diet-induced obesity (3, 8, or 16 weeks of diet) and in aged mice (1, 6-7, and 10-15 months).

RESULTS

The data confirmed the presence of macrophages and eosinophils, as previously reported, and showed that 20% to 30% of the immune cells in BAT were B cells. The number of B cells and eosinophils increased with diet-induced obesity, whereas macrophages decreased. There was no change in number of any immune cell quantified with age.

CONCLUSIONS

These studies reveal a novel finding of B220 + B cells in BAT and show that BAT immune cell populations change in response to diet-induced obesity.

Abstract A16: Smad4 pathways modulate induction of the chemokine Ccl20 and repress inflammation-induced carcinogenesis in mouse colon

Inflammation regulates many aspects of gut homeostasis but is also a key component of colon cancer progression. While TGFβ signaling is known to regulate inflammatory responses within immune cells, we have uncovered a novel regulatory pathway in which TGFβ and BMP signaling suppress responses to inflammatory stimuli within the colonic epithelium. Using mice with conditional deletion of Smad4 in intestinal epithelium, we found that CCL20 expression was increased with Smad4 loss. Similarly, in murine immortalized colonocytes and human colon cancer cell lines, blocking TGFβ and/or BMP receptors increased CCL20 expression. CCL20 is upregulated in response to inflammatory signals such as TNF and IL-1β. CCL20 is also upregulated in colon cancer but the mechanism is not understood. We found that pre-treatment of colonocytes or colon cancer cells with TGFβ1 and BMP2 completely suppressed TNF- or IL-1β-induced CCL20 expression at the level of gene transcription. By chromatin immunoprecipitation, we found that TGFβ1/BMP2 treatment impaired binding of NFκB and phospho-STAT3 to the CCL20 promoter. To understand the significance of this regulation in chronic inflammation, we subjected Smad4 deleted and control mice to three rounds of dextran sodium sulfate (DSS)-mediated damage to the distal colon. We found that loss of Smad4 in mouse colonic epithelium was sufficient to induce tumorigenesis following damage-induced inflammation. Following DSS-mediated damage, Smad4-null epithelium developed invasive colorectal adenocarcinoma within two months of DSS treatment while Smad4+ control mice never develop tumors following DSS exposure. The Smad4 null tumors were histologically similar to those of human colitis-associated colon cancers. Prior to tumor formation, we saw an increase in CD8+ cells in Smad4-deleted colons, suggesting that tumor progression involves bidirectional crosstalk between the epithelium and immune cells and that this crosstalk is regulated in part by Smad4-mediated signaling within the epithelium. SMAD4, TGFβ receptors, or BMP receptors are often mutated in colon cancer. This loss of TGFβ and/or BMP signaling likely facilitates epithelial-immune cell crosstalk in colitis-associated colon cancers.

Citation Format: Anna L. Means, Tanner J. Freeman, Connie J. Weaver, Chanjuan Shi, Mary K. Washington, Bronson C. Wessinger, Tasia Brown, David K. Flaherty, Kevin P. Weller, Robert J. Coffey, Keith T. Wilson, Robert D. Beauchamp. Smad4 pathways modulate induction of the chemokine Ccl20 and repress inflammation-induced carcinogenesis in mouse colon. [abstract]. In: Proceedings of the AACR Special Conference on Colorectal Cancer: From Initiation to Outcomes; 2016 Sep 17-20; Tampa, FL. Philadelphia (PA): AACR; Cancer Res 2017;77(3 Suppl):Abstract nr A16.

Distributions of Cells and Neurons across the Cortical Sheet in Old World Macaques

According to previous research, cell and neuron densities vary across neocortex in a similar manner across primate taxa. Here, we provide a more extensive examination of this effect in macaque monkeys. We separated neocortex from the underlying white matter in 4 macaque monkey hemispheres (1 Macaca nemestrina, 2 Macaca radiata, and 1 Macaca mulatta), manually flattened the neocortex, and divided it into smaller tissue pieces for analysis. The number of cells and neurons were determined for each piece across the cortical sheet using flow cytometry. Primary visual cortex had the most densely packed neurons and primary motor cortex had the least densely packed neurons. With respect to differences in brain size between cases, there was little variability in the total cell and neuron numbers within specific areas, and overall trends were similar to what has been previously described in Old World baboons and other primates. The average hemispheric total cell number per hemisphere ranged from 2.9 to 3.7 billion, while the average total neuron number ranged from 1.3 to 1.7 billion neurons. The visual cortex neuron densities were predictably higher, ranging from 18.2 to 34.7 million neurons/cm2 in macaques, in comparison to a range of 9.3-17.7 million neurons/cm2 across cortex as a whole. The results support other evidence that neuron surface densities vary across the cortical sheet in a predictable pattern within and across primate taxa.

Multiparameter analysis of stimulated human peripheral blood mononuclear cells: A comparison of mass and fluorescence cytometry

Mass and fluorescence cytometry are quantitative single cell flow cytometry approaches that are powerful tools for characterizing diverse tissues and cellular systems. Here mass cytometry was directly compared with fluorescence cytometry by studying phenotypes of healthy human peripheral blood mononuclear cells (PBMC) in the context of superantigen stimulation. One mass cytometry panel and five fluorescence cytometry panels were used to measure 20 well-established lymphocyte markers of memory and activation. Comparable frequencies of both common and rare cell subpopulations were observed with fluorescence and mass cytometry using biaxial gating. The unsupervised high-dimensional analysis tool viSNE was then used to analyze data sets generated from both mass and fluorescence cytometry. viSNE analysis effectively characterized PBMC using eight features per cell and identified similar frequencies of activated CD4+ T cells with both technologies. These results suggest combinations of unsupervised analysis programs and extended multiparameter cytometry will be indispensable tools for detecting perturbations in protein expression in both health and disease.

Obesity induced by a high-fat diet is associated with increased immune cell entry into the central nervous system

Obesity is associated with chronic low-grade inflammation in peripheral tissues caused, in part, by the recruitment of inflammatory monocytes into adipose tissue. Studies in rodent models have also shown increased inflammation in the central nervous system (CNS) during obesity. The goal of this study was to determine whether obesity is associated with recruitment of peripheral immune cells into the CNS. To do this we used a bone marrow chimerism model to track the entry of green-fluorescent protein (GFP) labeled peripheral immune cells into the CNS. Flow cytometry was used to quantify the number of GFP(+) immune cells recruited into the CNS of mice fed a high-fat diet compared to standard chow fed controls. High-fat feeding resulted in obesity associated with a 30% increase in the number of GFP(+) cells in the CNS compared to control mice. Greater than 80% of the GFP(+) cells recruited to the CNS were also CD45(+) CD11b(+) indicating that the GFP(+) cells displayed characteristics of microglia/macrophages. Immunohistochemistry further confirmed the increase in GFP(+) cells in the CNS of the high-fat fed group and also indicated that 93% of the recruited cells were found in the parenchyma and had a stellate morphology. These findings indicate that peripheral immune cells can be recruited to the CNS in obesity and may contribute to the inflammatory response.

Use of flow cytometry for high-throughput cell population estimates in brain tissue

The large size of primate brains is an impediment to obtaining high-resolution cell number maps of the cortex in humans and non-human primates. We present a rapid, flow cytometry-based cell counting method that can be used to estimate cell numbers from homogenized brain tissue samples comprising the entire cortical sheet. The new method, called the flow fractionator, is based on the isotropic fractionator (IF) method (Herculano-Houzel and Lent, 2005), but substitutes flow cytometry analysis for manual, microscope analysis using a Neubauer counting chamber. We show that our flow cytometry-based method for total cell estimation in homogenized brain tissue provides comparable data to that obtained using a counting chamber on a microscope. The advantages of the flow fractionator over existing methods are improved precision of cell number estimates and improved speed of analysis.

CBA/J mice generate protective immunity to soluble Ag85 but fail to respond efficiently to Ag85 during natural Mycobacterium tuberculosis infection

In CBA/J mice, susceptibility to Mycobacterium tuberculosis (M.tb) is associated with low interferon-gamma (IFN-γ) responses to antigens (Antigen 85 (Ag85) and early secreted antigenic target-6 (ESAT-6)) that have been defined as immunodominant. Here, we asked whether the failure of CBA/J mice to recognize Ag85 is a consequence of M.tb infection or whether CBA/J mice have a general defect in generating specific T-cell responses to this protein antigen. We compared CBA/J mice during primary M.tb infection, Ag85 vaccination followed by M.tb challenge, or M.tb memory immune mice for their capacity to generate Ag85-specific IFN-γ responses and to control M.tb infection. CBA/J mice did not respond efficiently to Ag85 in the context of natural infection or re-infection. In contrast, CBA/J mice could generate Ag85-specific IFN-γ responses and protective immunity when this antigen was delivered as a soluble protein. Our data indicate that although M.tb infection of CBA/J mice does not drive an Ag85 response, these mice can fully and protectively respond to Ag85 if it is delivered as a vaccine. The data from this experimental model suggest that the Ag85-containing vaccines in clinical trials should protect M.tb susceptible humans.

Helicobacter pylori induction of eosinophil migration is mediated by the cag pathogenicity island via microbial-epithelial interactions

The host immune response directed against Helicobacter pylori is ineffective in eliminating the organism and strains harboring the cag pathogenicity island augment disease risk. Because eosinophils are a prominent component of H. pylori-induced gastritis, we investigated microbial and host mechanisms through which H. pylori regulates eosinophil migration. Our results indicate that H. pylori increases production of the chemokines CCL2, CCL5, and granulocyte-macrophage colony-stimulating factor by gastric epithelial cells and that these molecules induce eosinophil migration. These events are mediated by the cag pathogenicity island and by mitogen-activated protein kinases, suggesting that eosinophil migration orchestrated by H. pylori is regulated by a virulence-related locus.

A rapid and reliable method of counting neurons and other cells in brain tissue: a comparison of flow cytometry and manual counting methods

It is of critical importance to understand the numbers and distributions of neurons and non-neurons in the cerebral cortex because cell numbers are reduced with normal aging and by diseases of the CNS. The isotropic fractionator method provides a faster way of estimating numbers of total cells and neurons in whole brains and dissected brain parts. Several comparative studies have illustrated the accuracy and utility of the isotropic fractionator method, yet it is a relatively new methodology, and there is opportunity to adjust procedures to optimize its efficiency and minimize error. In the present study, we use 142 samples from a dissected baboon cortical hemisphere to evaluate if isotropic fractionator counts using a Neubauer counting chamber and fluorescence microscopy could be accurately reproduced using flow cytometry methods. We find greater repeatability in flow cytometry counts, and no evidence of constant or proportional bias when comparing microscopy to flow cytometry counts. We conclude that cell number estimation using a flow cytometer is more efficient and more precise than comparable counts using a Neubauer chamber on a fluorescence microscope. This method for higher throughput, precise estimation of cell numbers has the potential to rapidly advance research in post-mortem human brains and vastly improve our understanding of cortical and subcortical structures in normal, injured, aged, and diseased brains.

Interleukin-10 promotes Mycobacterium tuberculosis disease progression in CBA/J mice

IL-10 is a potent immunomodulatory cytokine that affects innate and acquired immune responses. The immunological consequences of IL-10 production during pulmonary tuberculosis (TB) are currently unknown, although IL-10 has been implicated in reactivation TB in humans and with TB disease in mice. Using Mycobacterium tuberculosis-susceptible CBA/J mice, we show that blocking the action of IL-10 in vivo during chronic infection stabilized the pulmonary bacterial load and improved survival. Furthermore, this beneficial outcome was highly associated with the recruitment of T cells to the lungs and enhanced T cell IFN-gamma production. Our results indicate that IL-10 promotes TB disease progression. These findings have important diagnostic and/or therapeutic implications for the prevention of reactivation TB in humans.

Age dependent increase in early resistance of mice to Mycobacterium tuberculosis is associated with an increase in CD8 T cells that are capable of antigen independent IFN-gamma production

The lungs of naïve 18-month-old mice contain an abundant resident population of CD8 T cells that express typical markers of memory, express elevated levels of Th1 cytokine receptors on their surface, and are capable of non-specific IFN-gamma production in response to a Th1 cytokine cocktail. In this study we characterize this population of CD8 T cells in the lungs and spleens of mice with increasing age. In general, the proportion of CD8 T cells expressing markers of memory and Th1 cytokine receptors increased with age. The enhanced ability of CD8 T cells to produce IFN-gamma in an antigen independent manner followed this pattern as well, beginning to increase between 6 and 12 months of age. Interestingly, the phenotypic and functional age-related changes in CD8 T cells were also associated with a progressive age-related increase in early resistance to Mycobacterium tuberculosis. Taken together, these data suggest that as mice age a population of memory CD8 T cells, that are capable of contributing to innate immune responses to M. tuberculosis, gradually emerges and could be relevant for developing strategies to enhance immunity in the elderly.

Exposure to Mycobacterium avium can modulate established immunity against Mycobacterium tuberculosis infection generated by Mycobacterium bovis BCG vaccination

Mycobacterium bovis bacille Calmette Guerin (BCG), the current vaccine against infection with Mycobacterium tuberculosis, offers a variable, protective efficacy in man. It has been suggested that exposure to environmental mycobacteria can interfere with the generation of BCG-specific immunity. We hypothesized that exposure to environmental mycobacteria following BCG vaccination would interfere with established BCG immunity and reduce protective efficacy, thus modeling the guidelines for BCG vaccination within the first year of life. Mice were vaccinated with BCG and subsequently given repeated oral doses of live Mycobacterium avium to model exposure to environmental mycobacteria. The protective efficacy of BCG with and without subsequent exposure to M. avium was determined following an aerogenic challenge with M. tuberculosis. Exposure of BCG-vaccinated mice to M. avium led to a persistent increase in the number of activated T cells within the brachial lymph nodes but similar T cell activation profiles in the lungs following infection with M. tuberculosis. The capacity of BCG-vaccinated mice to reduce the bacterial load following infection with M. tuberculosis was impaired in mice that had been exposed to M. avium. Our data suggest that exposure to environmental mycobacteria can negatively impact the protection afforded by BCG. These findings are relevant for the development of a vaccine administered in regions with elevated levels of environmental mycobacteria.

Th1 cytokines facilitate CD8-T-cell-mediated early resistance to infection with Mycobacterium tuberculosis in old mice

Numerous immunological defects begin to emerge as an individual ages, the consequence of which is heightened susceptibility to infectious diseases. Despite this decline in immune function, old mice display an early transient resistance to Mycobacterium tuberculosis infection in the lung, which is dependent on CD8 T cells and gamma interferon (IFN-gamma) production. In this study, we investigated the mechanism of resistance by examining the CD8-T-cell phenotype and function in old naïve and M. tuberculosis-infected mice. Pulmonary CD8 T cells from naïve old mice expressed cell surface markers of memory in addition to receptors for several Th1 cytokines. Stimulation of lung cells from naïve old mice with a combination of Th1 cytokines (interleukin-2 [IL-2], IL-12, and IL-18) resulted in nonspecific production of IFN-gamma by memory CD8 T cells. Following aerosol infection with M. tuberculosis, the lungs of old mice contained significantly more IL-12, IL-18, and IFN-gamma than the lungs of young mice contained. Together, these data demonstrate that the increased and early production of Th1 cytokines in the lungs of M. tuberculosis-infected old mice, in combination with CD8 T cells that can nonspecifically produce IFN-gamma, leads to transient control of M. tuberculosis growth in the lungs of old mice. Further characterization of this mechanism should provide essential information regarding the aging immune system and should contribute to the development of novel strategies to decrease the morbidity and mortality of the aging population associated with infectious diseases.

Aging and lymphocyte subsets in the spleen and peripheral blood of the Sprague-Dawley rat

This study was undertaken to determine the effects of aging on lymphocyte subsets in the peripheral blood and spleens of Sprague-Dawley rats. Rats aged 3,13 and 26 months were used in the study. Analyses of dual labeled lymphocytes from the 26 month animals show decreases in the numbers of lymphocytes due to decreased cellularity (spleen) or reduced lymphocyte percentages within the total white blood cell population (peripheral blood). In the spleens and blood of the oldest rats, there were reduced numbers of Total T, T helper/amplifier (Th/a), virgin Th and natural killer (NK) cells. Other changes were observed in the spleen but not peripheral blood. The numbers of T cytotoxic/suppressor cells (Tc/s) B cells, "autoimmune" B cells and NK cells were reduced in the spleen but remained within normal limits in peripheral blood. The data show aging exerts different effects on the peripheral blood and splenic compartments of the immune system. These differences may have teleological significance in relation to immune responses to xenobiotics and neoplastic cells.

A new mask filter cartridge used to determine applicator inhalation exposure to an alachlor herbicide (Lasso) during normal spraying operations

A filter cartridge with a low air-flow resistance was designed for use on a modified half-face respirator worn during the application of alachlor (Lasso) herbicide. The filter trapped large concentrations of alachlor while retaining the ability to trap small respirable droplets. Moreover, alachlor could be recovered from the disassembled cartridge and analyzed by conventional methods. The test cartridges were used in combination with conventional personal air samplers to determine whether the filters trapped more alachlor when compared with personal samplers and to determine accurately the amount of alachlor reaching the breathing zone. Farmers sprayed alachlor in the form of alachlor (N = 7) or alachlor mixed with other herbicides or surfactant (N = 15). An average of 4 x 10(-2) mg or 2 x 10(-4) mg/kg of applied alachlor reached the respirator filters. This concentration was 10-fold higher than the alachlor recovered from the personal samplers. The new filter cartridge is better for determining the amount of alachlor reaching the breathing zone, and there is a low potential for significant inhalation exposure to alachlor during normal spraying operations.

The effect of continuous corticosterone administration on lymphocyte subpopulations in the peripheral blood of the Fischer 344 rat as determined by two color flow cytometric analyses

This study was undertaken to determine the effects of continuous corticosterone administration on lymphocyte subsets in the peripheral blood of Fischer 344 rats. Pellets which released corticosterone over a 21 day period (0.07 mg/day, 0.48 mg/day and 4.8 mg/day) were implanted subcutaneously in male rats. Control rats received pellets containing only the excipient carrier. Rats in the test and control groups were sacrificed at 7, 14 and 21 days. Lymphocyte subsets were enumerated by dual color flow cytometry and the data expressed in absolute numbers/mm3. Effects were observed only in the animals treated with the highest dose which was 70,000 times the normal plasma level. The spleen, thymus and lymph nodes were examined for histopathological changes. At the seven day sacrifice there was a statistically significant decrease in total white blood cells and selective decrements in lymphocytes with reductions in the absolute numbers of the T helper/amplifier, T cytotoxic/suppressor and B cells. Only numbers of natural killer cells were within normal limits. Histopathological data from animals treated with the high dose corticosterone for seven days demonstrated decreased thymic weights and a loss of thymic lymphocytes. At 14 and 21 days, the numbers of lymphocytes returned to the normal range, but the numbers of total T cells remained decreased. Also, thymic weights were reduced but not histological abnormalities were observed in the thymus. The data suggest that corticosterone induced a persistent decrease in total T cells, but only a transient effect on total lymphocytes.

The effect of Lasso herbicide on human immune function as measured by in vitro assays

Using in vitro assays, this study was undertaken to determine whether the components of Lasso herbicide formulation had an effect on the human immune system. Mononuclear cells from human peripheral blood were exposed to analytical alachlor, alachlor conjugated to human serum albumin or Lasso formulation over a concentration range from .01 microM-1.0 microM. The effects of the test materials on the following immunological functions were determined: lymphocyte proliferation induced by mitogen or antigen; antibody synthesis of IgG and IgM isotypes in pokeweed stimulated mononuclear cell cultures; cytotoxic T cell proliferation; lysis of target cells by natural killer cells and lymphokine activated killer cells. The data demonstrated that the test compounds had no significant, dose related effect on the function of immunocompetent cells. Hence, the data suggest that the components of the Lasso formulation have no effect on the human immune system.

In vitro immunologic studies on a population of workers exposed to phthalic and tetrachlorophthalic anhydride

In vitro radioallergosorbent tests have not been useful in identification of subjects with symptomatic allergic responses to acid anhydrides. By using phthalic anhydride or tetrachlorophthalic anhydride conjugated to human serum albumin, a study was undertaken to determine whether histamine release from basophils or lymphocyte transformation correlated with clinical symptoms, circulating anhydride specific IgE, and skin test reactivity. The data demonstrate that only histamine release from basophils correlated with symptoms and skin test reactivity. We conclude that in vitro histamine assays can be used in the identification of subjects with allergic responses to anhydrides.

Isolation and characterization of a new Cytophaga species implicated in a work-related lung disease

A yellow-pigmented, gram-negative, gliding bacterium isolated from an industrial water spray air humidification system was implicated as a causative agent in several occurrences of lung disease with hypersensitivity pneumonitis-like symptoms. The bacterium, designated WF-164, lacked microcysts or fruiting bodies and had a DNA base composition of 34.8 mol% of guanine plus cytosine. Gliding, flexing, nonflagellated cells measuring 0.3 by 3.5 to 8.9 micron were observed by using light and electron microscopy. Tests to determine utilization of selected carbohydrates revealed an amylolitic, chitinoclastic, noncellulytic bacterium. A number of additional biochemical and physiological tests were performed. DNA homology studies detected a 77.8% similarity to Cytophaga aquatilis (ATCC 29551). Comparisons of cellular fatty acid and carbohydrate contents of isolate WF-164 with a Flexibacter sp., several Cytophaga spp., and Flavobacterium reference strains revealed similar patterns to that of C. aquatilis. On the basis of these characteristics, isolate WF-164 was identified as a new Cytophaga sp.

A Cytophaga species endotoxin as a putative agent of occupation-related lung disease

A previous study suggested that a biologically active bacterial endotoxin was a putative agent of lung disease in a textile-producing facility. The endotoxin was isolated from the biomass growing in a chilled-water spray air humidification system. The bacterial flora of the air humidification system were isolated and taxonomically identified to the genus level. By using indirect immunofluorescence assays, a serologically reactive Cytophaga species was identified. A serologically reactive, biologically active (Limulus assay) endotoxin was purified from phenol extracts of the Cytophaga species. The endotoxin contained sugars, hexosamines, and lipids identical to those found in the humidifier biomass endotoxin. All subjects with biopsy-proven and suspected lung disease had antibodies directed toward the purified Cytophaga endotoxin. The data suggest that the Cytophaga endotoxin is the putative agent of lung disease in the textile facility.

Bacterial endotoxin isolated from a water spray air humidification system as a putative agent of occupation-related lung disease

Outbreaks of hypersensitivity pneumonitis or humidifier fever were attributed to the inhalation of organic material aerosolized by a chilled-water spray humidification system. The purpose of this study was to isolate and characterize the serologically detectable antigen(s) present in extracts obtained from the humidification system. By using bicarbonate or phenol-water extractions or both, the antigen was isolated and characterized, using colorimetry, gas-liquid chromatography, reverse-phase high-performance liquid chromatography, and X-ray fluorescence. Carbohydrates, hexosamines, phosphorus, and even-numbered saturated and unsaturated fatty acids were constituents of the serologically detectable antigen. When tested in in vivo and in vitro assays, the antigen had demonstrable endotoxin activity. All subjects with biopsy-proven lung disease and a majority of subjects suspected of having lung disease had antibodies directed toward the purified endotoxin. The data strongly suggest that an aerosolized bacterial endotoxin is a putative agent inducing lung disease.

Importance of anti-lung antibody in farmer's lung disease

The presence of anti-lung antibody was evaluated in 20 patients with farmer's lung disease. Antibody was found in 14. In patients with disease of less than five years' duration, there was no evidence of any significant differences in vital capacity, total lung capacity, diffusion capacity, and PaO2 between those with and without anti-lung antibody. However, in patients with disease of longer than five years' duration, the diffusion capacity was lower in the anti-lung antibody-positive group (p less than 0.05). The prevalence of abnormalities of vital capacity and diffusion capacity and fibrosis on chest roentgenograms was higher in those who had anti-lung antibody and disease of more than five years' duration. The study suggests that anti-lung antibody is present before permanent measurable physiologic abnormality occurs and may potentiate the pulmonary damage during subsequent episodes.

Immunological studies on Alternaria sensitivity. Use of crossed radioimmunoelectrophoresis, precipitins and enzyme-linked immunosorbent assay

Characterization of the immunological response to Alternaria in sensitive subjects is not complete. We used crossed radioimmunoelectrophoresis (CRIE) to identify antigens in Alternaria extracts reacting with IgE antibody in five patients with Alternaria-sensitive asthma, four with Alternaria-induced rhinitis, three non-allergic asthmatics, and three normal controls. All five Alternaria-asthma patients and three of four Alternaria-rhinitis patients showed IgE binding to a third antigen. These results suggest an analogy of Alternaria antigens with that found in ragweed pollen extracts, i.e. that IgE antibody is directed against more than one antigen. Using the enzyme-linked immunosorbent assay (ELISA), we found a significant difference (P less than 0.05, unpaired Student's t-test) in IgG binding between Alternaria-sensitive asthmatics and normal controls. There was no apparent difference in IgG binding between untreated Alternaria-sensitive asthmatics and those receiving high-dose immunotherapy.

Immunological responses to training in conditioned runners

1. We measured the concentrations of leucocyte subpopulations, immunoglobulins and complement in six well-conditioned runners before and after a typical 8-mile (12.8 km) training run at 70-75% of VO2 max. 2. Before running all components were within the normal range. Exercise failed to produce a significant rise in neutrophils. There was also no change in immunoglobulins or complement concentrations immediately or 24 h after exercise. Lymphocyte subpopulations were also unchanged except for a progressive rise in antibody-dependent cytotoxic effector cells (K-lymphocytes). 3. These results suggest chronic exercise training has no apparent adverse effect on circulating cellular or humoral immune components in healthy subjects. An increase in K-lymphocytes may provide added host defence capacity during periods of stress, although the mechanism of increase is unexplained.

HLA antigen frequencies and natural history in Alternaria-sensitive and perennial nonallergic asthmatics

The frequency of HLA-A, -B, and -C loci antigens in random populations of Alternaria-sensitive (N = 100) and perennial nonallergic asthmatics (N = 87) were compared with age- (+/- 5 yr) and sex-matched controls from the same geographic region. There was no association between HLA antigens as measured by frequency analyses and Alternaria-sensitive or perennial nonallergic asthma. Moreover there was no association between HLA antigens and the age of onset of asthma, associated allergic disorders, various environmental factors provoking asthma, total serum IgE levels, and Alternaria-specific IgE antibody.

Serum IgE levels in toxoplasmosis

Elevated levels of serum IgE are found in many helminthic parasitic diseases. The authors have previously demonstrated that giardiasis, amoebiasis and Chagas' disease were not associated with hyperimmunoglobulinaemia E. To determine the influence of toxoplasma gondii on IgE levels of clinically symptomatic patients, a controlled study was performed. There was no difference found between the serum IgE values from Brazilian patients with toxoplasmosis and those from matched healthy Brazilian controls. This again confirms that protozoan parasitic infections do not increase serum IgE levels.

Serologically detectable HLA-A, B, and C loci antigens in farmer's lung disease

The frequency of serologically detectable (SD) HLA-A, B, and C loci antigens in subjects with farmer's lung disease (N = 100) was compared with that of age- and sex-matched normal normal farmers with no precipitating antibodies to extracts of thermophilic actinomycetes. A subset of the farming population with antibodies to the thermophilic actinomycetes and no evidence of clinical disease (N = 55) was also agae- and sex-matched to the farmer's lung disease population. No significant associations between any of the SD HLA antigens tested and farmer's lung disease were found in the study. The data demonstrated that there was no association between SD HLA antigens and farmer's lung disease in random populations.

Serum IgE levels in amoebiasis

Elevated levels of serum immunoglobulin E (IgE) are found in many parasitic diseases. In order to determine the influence of Entamoeba histolytica on IgE levels of clinically symptomatic patients with intestinal amoebiasis, a controlled study was performed. There was no difference between the serum IgE values from Brazilian patients with amoebiasis and those from age-, race- and sex-matched normal Brazilian controls. Based also on our previous similar studies on giardiasis and Chagas' disease, we conclude that protozoan infections do not elevate serum IgE levels.

Absence of inhibitory effect of leprosy sera upon normal E rosetting

Inhibitory serum factors in certain infectious diseases (leprosy, tuberculosis, histoplasmosis) and malignant conditions (Hodgkin's disease, primary intracranial neoplasms) are said to be partially responsible for decreased cell-mediated immunity (CMI) and consequent anergy. The immunologic derangement in leprosy is not yet completely understood. In order to determine the effect of sera from patients with leprosy upon the rosetting capacity of normal T. lymphocytes, sera from untreated lepromatous (L) and tuberculoid (T) patients were studied. Control sera were obtained from normal volunteers and from patients with other dermatologic conditions (contact dermatitis and leg ulcer). The data indicated that test sera did not inhibit either spontaneous E rosette formation or active rosetting of normal lymphocytes.

Antibody-dependent cellular cytotoxicity of mononuclear cells from asthmatics tested in three in vitro assays

Using the chicken red blood cell assay, the human Chang liver cell assay, and a lymphoblastoid cell assay, mononuclear cells from asthmatics and normals were tested for antibody-dependent cellular cytotoxicity (ADCC) capacity. Mononuclear cell preparations from perennial nonallergic asthmatics with a history of asthma associated with viral infections had a reduced ADCC capacity in the chicken red blood cell assay, an increased ADCC capacity in the Chang liver cell assay, and normal ADCC capacity in the lymphoblastoid cell assay. The data also suggested that perennial nonallergic asthmatics had increased percentages of surface IgG-negative lymphocytes in the peripheral blood when compared to normals.

Response to corticosteroids in the hypereosinophilic syndrome. Association with increased serum IgE levels

Severe blood eosinophilia (16,500/cu mm and 6,500/cu mm) accompanied by involvement of the lungs, pleura, heart, pericardium, liver, gastrointestinal tract, peripheral nerves, or skin developed in two patients with bronchial asthma. Associated with the eosinophilia were elevated serum IgE levels (1,400 IU/ml and 10,500 IU/ml), depressed serum C4 complement levels (13 mg/100 ml and 6 mg/100 ml), and high titers of rheumatoid factor (1:2560 and 1:640). Symptoms improved after treatment with prednisone and the eosinophil counts and serum IgE and C4 complement levels returned to normal.

Serum IgE levels in Chagas' disease

Elevated levels of serum immunoglobulin E are found in many parasitic diseases caused by helminths. We have previously demonstrated that giardiasis was not associated with hyperimmunoglobulinaemia E. In order to determine the influence of Trypanosoma cruzi on IgE levels of clinically symptomatic patients, a controlled study was performed. There was no difference between the serum IgE values from Brazilian patients with Chagas' disease and those from matched healthy Brazilian controls. We suggest that protozoan parasitic infections do not increase serum IgE levels.

HLA antigen frequencies in allergic bronchopulmonary aspergillosis

The frequency of HLA antigens in twenty-two Caucasian patients with allergic broncho-pulmonary aspergillosis (ABPA) and sixty-nine unrelated Caucasian controls was determined. The results indicated that there was no increased frequency of a specific HLA antigen in patients with ABPA. Moreover, studies in thirteen families of ABPA patients also demonstrated that, within families, there was no consistent association between a specific haplotype and asthma, allergies or hay fever.

Serum IgE levels in giardiasis

Raised levels of serum immunoglobulin E are found in many parasitic diseases. In order to determine the influence of Giardia lamblia on IgE levels of clinically symptomatic patients, a controlled study was performed. There was no difference between the serum IgE values from Brazilian patients with giardiasis and those from normal Brazilian controls, although in both groups there were many individuals with values higher than the normal range reported from the northern hemisphere.

Frequency of W4 and W6 antigens in perennial, nonallergic asthmatics

The frequency of W4 and W6 antigens was determined in 39 perennial, nonallergic asthmatics and 53 normal controls. The data indicated that the frequency of asthmatics homozygous for W4 or W6 was not different from the unrelated control population. Hence, our data dispute the hypothesis that intrinsic asthma is an autosomal-recessive disease associated with the W6 antigen.

Correlation of exposure to various respiratory pathogens with farmer's lung disease

Complement-fixing antibodies (CFA) to a panel of microorganisms commonly associated with respiratory disease were measured in a number of agricultural populations. The panel included Mycoplasma pneumoniae, influenza viruses A and B, parainfluenza virus types 1, 2, and 3, adenovirus, and respiratory syncytial virus. The agricultural populations were grouped according to a clinical history of farmer's lung disease (FLD) and the presence of antibodies to the thermophilic actinomycetes (TA). Farmers with precipitating antibody activity to one or more of the TA (groups I and II) demonstrated a greater frequency of CFA to M. pneumoniae and parainfluenza virus types 1, 2, and 3 than those groups without antibody to the TA, but the level of CFA was not higher in the positive subjects. Immunoglobulin levels were also elevated in groups I and II when compared to the control groups. Unlike IgG and IgM, IgA was elevated only in the farmers who had a clinical history of FLD (group I) but not in farmers without a clinical history. The results suggest that farmers who develop FLD are exposed to a wider variety of pathogens than are other farmers, but do not respond in an accelerated manner.

Lymphopenia in acute nitrofurantoin pleuropulmonary reactions

Each of 5 patients with acute nitrofurantoin pleuropulmonary reactions had profound lymphopenia and 4 had eosinophilia developing early in the clinical course after the drug was withdrawn. The 2 patients tested had only one third of the normal numbers of E rosettes (T lymphocytes) in the peripheral blood during recovery. Lymphoblastic transformation tests with purified nitrofurantoin were done in 3 patients and all of them were negative; responses to phytohemagglutinin, concanavalin A, and pokeweed were decreased but still normal. The diagnosis of various nitrofurantoin hypersensitivity reactions relies on clinical data. The mechanisms of these reactions presently remain unclear.