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FAM13A polymorphism is associated with a usual interstitial pneumonia pattern in patients with systemic sclerosis-associated interstitial lung disease.

OBJECTIVES: The MUC5B promoter single nucleotide polymorphism (SNP) rs35705950 has been associated with idiopathic pulmonary fibrosis (IPF) and RA-related interstitial lung disease (ILD), but not with SSc-ILD. We hypothesized that the MUC5B promoter polymorphism or other IPF susceptibility loci are associated with an increased risk for the uncommon SSc-usual interstitial pneumonia (UIP) endophenotype, rather than SSc-ILD in general. METHODS: We performed a cross-sectional study of SSc-ILD patients from four US Scleroderma Programs to investigate the frequency of MUC5B rs35705950 and 12 additional IPF susceptibility loci. SSc-ILD patients were stratified by high resolution chest CT (HRCT) imaging findings into UIP and non-UIP groups. Analysis of HRCTs performed by a thoracic radiologist blinded to participants' characteristics classified each scan as definite UIP, probable UIP, indeterminate or alternative diagnosis, according to American Thoracic Society criteria. RESULTS: Four-hundred and eighty-nine SSc-ILD patients were included; 80% were female and 75% were White. Twenty-three (4.7%) patients had a definite UIP pattern. The MUC5B SNP rs35705950 was not associated with a definite UIP pattern in SSc-ILD. In contrast, patients carrying two copies of the IPF risk gene FAM13A minor allele rs2609255 had significantly higher odds of a definite UIP pattern compared with the other patterns (odds ratio 3.40, 95% CI 1.19-9.70), and compared with an alternative diagnosis (odds ratio 3.65, 95% CI 1.25-10.65). CONCLUSION: We demonstrated a novel association between FAM13A and SSc-UIP. Contrary to IPF and RA-ILD, the MUC5B promoter polymorphism was not associated with a definite UIP pattern in SSc-ILD.

Humans

Virulence of bacteria-associated, Crithidia-associated, and axenic Entamoeba histolytica: experimental hamster liver infections with strains from patients and carriers.

Experimental infections of the hamster liver were carried out with five strains from patients with clinical amoebiasis and ten strains from asymptomatic carriers. Inocula of comparatively small size (12000-36000 amoebae) were injected under the liver capsule. 1. The virulence of the patient strains varied from 21-96% (see article) and declined sharply within 7-15 weeks after elimination of the associated bacterial flora. The virulence of the carrier strains varied from 0-100%, probably fluctuating with changes in the concomitant bacterial flora (Table 1). 2. The interrelation between size of inoculum, period of bacteria-free growth, and virulence was demonstrated with a Crithidia-associated patient strains (Table 2). 3. A patient strain showed a faster decrease of virulence during axenic than in Crithidia-associated cultivation (Table 3). 4. Two successive passages through hamster liver resulted in a marked increase of virulence of two bacteria-free strains, lasting for several months (Table 4). 5. A significant enhancement of virulence of Crithidia-associated and axenic amoebae by reassociation with a mixed bacterial flora during two weeks, followed by elimination of the bacteria, was demonstrated with two strains. The restored virulence was lost again within a few weeks (Table 5). 6. The virulence of an attenuated patient strain did not become manifest by adding large numbers of dead amoebae to the inoculum (Table 6). 7. The pathology of the different lesions caused in the hamster liver by the amoebae is described, including one of a granulomatous type, frequently found after inoculation with bacteria-free amoebae. 8. In an attempt to explain the occurrence of strains differing in pathogenicity an hypothesis is put forward based on the idea of selection of virulence and avirulent amoebae.

Amebiasis

Bioinformatic analysis reveals the potential association of ESRP1 with the splicing of cytoskeleton-associated genes in doxorubicin-resistant MCF7 breast cancer cells.

BACKGROUND: Breast cancer remains one of the most prevalent malignancies among women, with doxorubicin resistance posing a significant challenge that undermines treatment success and survival outcomes. Aberrant alternative splicing (AS), driven by dysregulation or mutations in splicing factors (SFs), is implicated in cancer initiation, progression, and drug resistance. This study aims to investigate the association of the epithelial cell-specific splicing factor ESRP1 with doxorubicin resistance in breast cancer, focusing on how ESRP1 deficiency correlates with AS changes that promote chemoresistance. METHODS: We analyzed RNA-sequencing (RNA-seq) data from doxorubicin-resistant (MCF7-DR) and parental (MCF7) breast cancer cell lines to identify enhanced alternative splicing events (ASEs) and changes in ESRP1 expression; we further leveraged The Cancer Genome Atlas (TCGA)-BRCA cohort to construct an SF-RASE correlation network for screening core SFs (including ESRP1). An integrative analysis combining crosslinking immunoprecipitation (CLIP-seq) data and The Cancer Genome Atlas (TCGA) database was performed to validate ESRP1 binding targets and assess the association between ESRP1-related splicing and cytoskeleton organization. RESULTS: We observed extensive AS changes and significantly downregulated ESRP1 expression in MCF7-DR cells. Integrative analysis identified 61 high-confidence ASEs that correlate with ESRP1 expression. Further bioinformatic integration suggests that ESRP1 expression is associated with the splicing patterns of SPTBN1, MAP2K7, FGFR3, and CYB561A3-four genes involved in cytoskeleton organization-though direct experimental verification to confirm a causal regulatory relationship between ESRP1 and the splicing of these genes is still pending. CONCLUSIONS: Our findings suggest that ESRP1 expression is closely associated with doxorubicin resistance in breast cancer cells, with concomitant alterations in key ASEs linked to cytoskeletal remodeling that correlate with ESRP1. Exploring the ESRP1-related splicing network may offer new strategies to overcome chemoresistance and improve patient outcomes. However, the small cell line sample size (n = 2 per group) constrains the robustness of ASE and SF-ASE correlation findings, and these results should be interpreted with caution and require further validation with larger sample cohorts.

Alternative splicing

Investigations on purine and pyrimidine bases stacking associations in aqueous solutions by the fluorescence quenching method. III. Intramolecular association of 9,9'-[1,3-propylene]-bis-2-aminopurine.

General equations relating fluorescence quantum yield and lifetime of a compound with its intramolecular stacking equilibrium and kinetics were derived. Intramolecular stacking association of 9,9'-[1,3-propylene]-bis-2-aminopurine in aqueous solution was examined within the range of temperatures from 0 to 90 degrees C. A two-state thermodynamic model of the association was verified. The stacking enthalpy and entropy can be taken, with a good approximation, as temperature-independent (deltaH equals - 2.0 kcal/mol, deltaS=-3.25 e.u.) although the function deltaG=-0.00886T2 + 8.847 T - 2876 describes more precisely the observed changes of stacking free enthalpy with temperature. The association rate constants were detemined. Activation energy of the reaction (2 kcal/mol) is the same as in the case of association between free 2-aminopurine molecules. It confirms a two-step mechanism of the process. The advantages and shortcomings of the fluorescence quenching method are discussed.

2-Aminopurine

Selenoprotein S associates with complexes governing membrane protein biogenesis and translation-associated processes.

Human selenoprotein S (selenos) is part of the integrated cellular stress response and linked to protein quality control and signaling pathways. Consequently, genetic polymorphisms of selenos are associated with increased risks for diabetes, dyslipidemia, and cardiovascular diseases. Determining the specific roles of selenos in these cellular pathways and diseases has been challenging, as selenos associates with a wide range of protein complexes. Thus, to map the cellular functions of selenos and uncover their interconnections, we used affinity purification and in vivo crosslinking to stabilize transient protein interactions, followed by proteomics to record the resulting selenos interactome. Through mapping of selenos protein partners, we found evidence that selenos associates with complexes responsible for the insertion of membrane proteins into the endoplasmic reticulum (ER) bilayer and their connected quality control components. Furthermore, selenos is also part of metabolic, trafficking, and mitochondrial pathways. Notably, proteins involved in translation preferentially associate with selenos when its C-terminal intrinsically disordered segment containing the redox-active motif is accessible. Together, these results identify the C-terminal redox loop of selenos as a central interaction hub connecting translation with ER membrane protein biogenesis and quality control.

Selenoproteins

Association of the folded chromosome with the cell envelope of Escherichia coli: nature of the membrane-associated DNA.

Membrane-associated folded chromosomes isolated from Escherichia coli in the presence of spermidine sedimented at about 5,800S. The folded chromosome and the membrane fragment were each stable in the absence of the other; a 1,700S folded chromosome was obtained after removal of the membrane by a Sarkosyl treatment, and a 4,000S membrane fragment remained after digestion of the chromosomal DNA with deoxyribonuclease I. The interaction between the folded chromosome and the membrane fragment was stable, and, even when the DNA was unfolded, both components remained associated and cosedimented. The large frictional effect of the unfolded DNA reduced the sedimentation rate of the complex to about 2,000S. Partial removal of this unfolded DNA with restriction endonucleases caused the membrane fragments and the remaining associated DNA to sediment faster, at about 3,500S. The DNA remaining associated with the membrane fragments after restriction endonuclease treatment, about 4.5% of the total DNA when EcoRI was used, was indistinguishable from the DNA released from the membranes by three criteria: (i) DNA size distribution in agarose gels after electrophoresis, (ii) reassociation kinetics, and (iii) thermal elution from hydroxylapatite. This finding, that random DNA sequences rather than specific ones were responsible for the majority of the DNA-membrane interactions, argues against the folded chromosome's being a static structure with specific DNA sequences interacting with the cell envelope.

Cell Wall

Morphology of experimental antibiotic-associated enterocolitis in the hamster: a model for human pseudomembranous colitis and antibiotic-associated diarrhoea.

The morphology of antibiotic-associated enterocolitis in the hamster is described and compared with human antibiotic-associated pseudomembranous colitis. It is shown to be a caecal disease with proliferative mucosal changes and in this respect unlike the human counterpart. The bacteriology and toxicology, however, are identical. In addition, mucosal changes are described in animals on antibiotics but without established enterocolitis. As a result we suggest that there may be a spectrum of human disease ranging from mild antibiotic-associated diarrhoea to established pseudomembranous colitis. Therefore, despite the morphological variation, the hamster remains a good model for investigating the pathogenesis of pseudomembranous colitis and antibiotic-associated enteropathy in general.

Animals

Genome-wide association study reveals candidate genes associated with body weight and wool traits in Ordos fine-wool sheep.

BACKGROUND: The Ordos fine-wool sheep is a high-quality fine-wool breed in China, renowned for its excellent wool quality, meat production, and adaptability to the arid and semi-arid regions of Inner Mongolia. Body weight and wool traits are important economic characteristics in sheep breeding. This study aimed to identify genetic loci associated with body weight (BW), wool length (WL), and wool fineness (WF) in Ordos fine-wool sheep. METHODS: A genome-wide association study (GWAS) was conducted in 388 Ordos fine-wool sheep genotyped using the GenoBaits® Ovine 40K SNP panel. Single nucleotide polymorphisms (SNPs) associated with BW, WL, and WF were identified, and candidate genes located near the SNPs reaching the suggestive threshold were subjected to functional annotation and enrichment analysis. RESULTS: A total of 22 SNPs were identified as potentially associated with BW, WL, and WF traits, corresponding to 27 annotated genes. Functional annotation highlighted six potential candidate genes, including LAMA2, ARHGAP18, IGFBP2, IGFBP5, CA10, and AXIN1, which may play important roles in regulating body weight and wool growth in sheep. CONCLUSIONS: The identified genes provide valuable candidate loci for BW, WL, and WF traits in Ordos fine-wool sheep. The results of this study provide preliminary references for further exploration of the genetic mechanisms of wool traits in Ordos fine-wool sheep and the development of molecular breeding markers.

GWAS

A Guide for Exploring Pleiotropic Associations in Genome-Wide Association Studies Using Summary Statistics.

Genome-wide association studies (GWAS) have shown that pleiotropy, whereby a single genetic variant or gene influences multiple traits, is common in complex human diseases. Detecting cross-phenotype associations from GWAS summary statistics remains challenging because of small effect sizes, extensive multiple testing, heterogeneous effects, and possible differences in effect direction across traits. Methods that jointly analyze multiple traits can improve the ability to detect pleiotropic signals while retaining the practical advantages of summary statistic-based analyses. Although a range of statistical approaches has been developed for this purpose, practical guidance on their application, assumptions, and interpretation remains limited. This tutorial reviews several widely used methods for pleiotropy detection from GWAS summary statistics, including ASSET, PLACO, GPA, CPBayes, and GCPBayes, and demonstrates their application using breast and thyroid cancer datasets. We also highlight the importance of accounting for effect heterogeneity, correlation, and biological group structure at the gene and pathway levels in the detection and interpretation of pleiotropic association signals.

Genome-Wide Association Study

Association of lipoprotein-associated phospholipase A2 with recurrence risk and its predictive value in large artery atherosclerotic stroke.

OBJECTIVE: To investigate the association of lipoprotein-associated phospholipase A2 (Lp-PLA2) with large artery atherosclerotic (LAA) stroke and its predictive value for recurrence. METHODS: We consecutively enrolled 412 acute LAA stroke patients. Using a cutoff of 200&#xa0;ng/mL, patients were divided into high and low Lp-PLA2 groups, and into recurrence and non&#x2011;recurrence groups based on 1&#x2011;year follow&#x2011;up. Baseline characteristics, lipid profiles, National Institutes of Health Stroke Scale (NIHSS) scores, and vascular stenosis degree were compared. Binary logistic regression and Receiver Operating Characteristic (ROC) analysis were used to identify independent risk factors and evaluate predictive value. RESULTS: The high Lp-PLA2 group had significantly higher low-density lipoprotein cholesterol (LDL-C), small dense low-density lipoprotein cholesterol (sdLDL-C), prevalence of severe stenosis (&#x2265;70%), and proportion of NIHSS&#xa0;>&#xa0;15 (all P&#xa0;<&#xa0;0.05). The recurrence group showed elevated Lp-PLA2, higher LDL&#x2011;C and sdLDL-C, more severe neurological deficits, and more severe stenosis (all P&#xa0;<&#xa0;0.001). Multivariable regression identified elevated Lp-PLA2 (per 10&#xa0;ng/mL: OR&#xa0;=&#xa0;1.139, 95% CI: 1.089-1.191), moderate (OR&#xa0;=&#xa0;3.145) and severe (OR&#xa0;=&#xa0;11.663) neurological deficits, and severe stenosis (OR&#xa0;=&#xa0;9.390) as independent risk factors for recurrence (all P&#xa0;<&#xa0;0.05). The Area Under the Curve (AUC) of Lp-PLA2 was 0.75 (95% CI: 0.69-0.82), with an optimal cutoff of 208.95&#xa0;ng/mL. CONCLUSION: Elevated Lp-PLA2 is associated with adverse lipid profiles, more severe neurological deficits, and greater vascular stenosis in LAA stroke patients, and independently predicts 1&#x2011;year recurrence. Lp-PLA2 shows moderate predictive value, supporting its potential for risk stratification.

Humans

Plasma proteome profiling identifies XPNPEP3 as a novel biomarker associated with metabolic dysfunction-associated steatotic liver disease in patients with type 2 diabetes mellitus.

OBJECTIVE: To identify plasma protein differences between type 2 diabetes mellitus (T2DM) patients with and without metabolic dysfunction-associated steatotic liver disease (MASLD), and to evaluate the diagnostic potential of X-prolyl aminopeptidase 3 (XPNPEP3) for identifying MASLD in T2DM patients. METHODS: Twenty T2DM inpatients were categorized into groups with and without MASLD and their plasma samples&#xa0;were analyzed using data-independent acquisition mass spectrometry, followed by bioinformatics analysis to identify differentially expressed proteins. The cohort was then expanded to 84 patients, and plasma XPNPEP3 levels were validated by enzyme-linked immunosorbent assay. Correlation between XPNPEP3 and clinical indicators were evaluated, and diagnostic performance was determined via receiver operating characteristic (ROC) analysis. Immunohistochemistry was employed to compare hepatic XPNPEP3 expression between the two groups. RESULTS: Proteomic analysis identified 176 differentially expressed proteins, with XPNPEP3 exhibiting the most significant down-regulation by fold change. In the validation cohort, plasma XPNPEP3 was significantly lower in T2DM+MASLD versus T2DM alone. XPNPEP3 levels were negatively correlated with diabetes duration, liver function markers, and triglyceride levels, and was identified as an independent factor inversely associated with MASLD in T2DM.ROC analysis demonstrated strong diagnostic performance for XPNPEP3, further enhanced when combined with BMI and diabetes duration.&#xa0; Immunohistochemistry confirmed reduced hepatic XPNPEP3 expression in T2DM+MASLD patients. CONCLUSIONS: Lower plasma XPNPEP3 is independently associated with MASLD in T2DM patients and demonstrates strong diagnostic potential, positioning XPNPEP3 as a promising biomarker for diagnosing MASLD in T2DM patients and a novel target for non-invasive diagnostic tool development.

Humans

A genome-wide association study identified 10 novel genomic loci associated with intrinsic capacity.

BACKGROUND: Intrinsic capacity (IC) is a multidimensional concept within the World Health Organization framework for healthy aging. It refers to the composite of an individual's physical and mental capacities that enable them to maintain well-being, functional ability, and engagement in valued activities throughout life. While substantial evidence supports the biological basis of IC and its subdomains, the extent to which genetic factors influence IC remains largely unexplored, with no studies currently available. METHODS: Using datasets from the UK Biobank (UKB; N&#x2009;=&#x2009;44 631) and the Canadian Longitudinal Study on Aging (CLSA; N&#x2009;=&#x2009;13 085), we implemented the restricted maximum likelihood method to estimate SNP-based heritability (h2snp), followed by a Genome-Wide Association Study (GWAS) to identify genetic variants associated with IC, and post-GWAS analyses to pinpoint biological implications. RESULTS: The h2snp for IC was estimated at 25.2% in UKB and 19.5% in CLSA. Our GWAS identified 38 independent SNPs for IC across 10 genomic loci and 4289 candidate SNPs, mapped to 197 genes. Post-GWAS analysis revealed the role of these genes in cellular processes such as cell proliferation, immune function, metabolism, and neurodegeneration, with high expression in muscle, heart, brain, adipose, and nerve tissues. Of the 52 traits tested, 23 showed significant genetic correlations with IC, and a higher genetic loading for IC was associated with higher IC scores. CONCLUSIONS: Overall, this study provides comprehensive evidence on the genetic architecture of IC, identifying novel genetic variants and biological pathways, advancing our current knowledge and laying the foundation for ongoing and future research on healthy aging.

Adult

Genetic predisposition to systemic inflammatory proteins is causally associated with inflammatory bowel disease: Insights from multi-omics association study and single-cell RNA-sequencing analysis.

Systemic inflammatory proteins have been reported to be related to inflammatory bowel disease (IBD) in previous observational research. However, their causal links remain obscure. Herein, we performed a Mendelian randomization (MR) analysis to analyze the causality between systemic inflammatory proteins and IBD. Genetic variants related to systemic inflammatory proteins were extracted from a meta-analysis of genome-wide association study (GWAS) data of 8293 European participants. Summary statistics of IBD diverse subtypes were obtained from the international IBD genetic consortium (IIBDGC). We conducted multi-omics method and MR study to detect the causal links through integrating GWAS and protein quantity trait loci (pQTL) data. Inverse variance weighted (IVW) approach was utilized as the dominated analysis method. Moreover, complementary approaches such as MR-Egger intercept test, Cochran Q test and leave-one-out analysis were utilized to validate pleiotropy and heterogeneity. Finally, single-cell RNA-sequencing analysis was performed to detect the expression of significant genes. For IBD, IVW estimates suggested that genetically predicted IL-10 and IL-13 were suggestively associated with an elevated risk of IBD (IL-10: OR: 1.12, 95% CI: 1.00-1.24, P&#x2005;=&#x2005;.04; IL-13: OR: 1.09, 95% CI: 1.01-1.18, P&#x2005;=&#x2005;.023), while CXCL10 was suggestively linked to a lower risk of IBD (CXCL10: OR: 0.90, 95% CI: 0.82-0.99, P&#x2005;=&#x2005;.037). For Crohn disease (CD), the IVW approach provided evidence to sustain that genetically determined IL-13 and CCL3 had a suggestive association with a higher risk of CD (IL-13: OR: 1.13, 95% CI: 1.02-1.26, P&#x2005;=&#x2005;.023; CCL3: OR: 1.22, 95% CI: 1.03-1.45, P&#x2005;=&#x2005;.018). Sensitivity analysis did not explore any heterogeneity and pleiotropy. Our findings supported the causal relationships between 4 specific inflammatory proteins (IL-10, IL-13, CXCL10, and CCL3) and the risk of IBD and CD, thereby providing promising biomarkers of various subtypes stratification and new insights for the prevention and therapeutic target of IBD.

Humans

Genome-wide association studies reveal genetic variants associated with antineoplastic monoterpenoid indole alkaloid accumulation in Catharanthus roseus.

Catharanthus roseus produces pharmacologically important monoterpenoid indole alkaloids (MIAs), yet their natural accumulation is low, limiting therapeutic exploitation. To dissect the genetic basis of natural variation in MIA accumulation, we integrated phenotypic, chemotypic, and genomic analyses of 93&#xa0;C. roseus accessions sampled from six locations across India, including New Delhi, Lucknow, Jodhpur, Bangalore, and two locations in Gujarat: Navsari and Bardoli. Morphological characterization showed limited differentiation among locations, whereas accessions from Gujarat tended to be taller compared to other locations and more frequently white-flowered. Quantitative HPLC profiling revealed substantial accession- and location-dependent variation in total indole alkaloid levels, with Gujarat accessions showing the highest accumulation, largely driven by vindoline and catharanthine. Genotyping-by-sequencing generated 10,801 high-quality variants comprising 10,087 SNPs and 714 InDels corresponding to an average density of 19.34 variants per Mbp of the genome, revealing three genetic subgroups with overall admixed ancestry and weak geographic stratification. Genome-wide association study (GWAS) using five benchmark models identified 47 variants potentially associated with catharanthine, vindoline, and vinblastine content. These putative candidate loci were located near genes implicated in hormone signaling, mitochondrial function, nitrogen metabolism, and RNA processing, suggesting complex regulatory control of MIA biosynthesis. Notably, two missense variants in a carboxylesterase-like gene were associated with vindoline accumulation, and highly significant intergenic SNP clusters suggested putative regulatory hotspots for vinblastine biosynthesis. These results provide GWAS-based insights into the genetic architecture of MIA metabolism in C. roseus and nominate candidate variants for precision breeding and metabolic engineering to enhance pharmaceutical alkaloid production.

Catharanthus roseus

Antigens of a human breast carcinoma cell line (BT 20). I. Synthesis of serum proteins, membrane-associated antigens, and oncofetal-associated antigens.

The synthesis of various products by a human mammary cell line (BT 20) was studied by incorporation of 14C-labeled amino acids, choline, glucosamine, or galactosamine into nondialyzable materials. These products had molecular weights ranging from less than 12,300 daltons to more than 200,000 daltons. They were analyzed by immunoelectrophoresis and double diffusion in agar. Among the synthesized products, the following proteins were identified: beta2-glycoprotein I, alpha2HS-glycoprotein, alpha2-lipoprotein, actin, beta2-microglobulin, carcinoembryonic antigen, three oncofetal-associated antigens, and various erythrocyte membrane-associated antigens (namely, glycophorin). Synthesis of milk proteins was not detectable. Only the protein moiety of the glycophorin molecule seemed to be synthesized. The beta2-microglobulin was synthesized in an unbound state as well as bound to a glycoprotein whose relationship with the transplantation or tumor antigens must be determined. The three oncofetal-associated antigens were also synthesized in vitro by human fetal tissues and neoplastic and dysplastic human mammary tissues.

Actins

Close association between Fc receptor and HLA-D-associated (Ia-like) determinants on human lymphoid cells.

The inhibitory effect of HLA antisera on Fc receptors of human lymphoid FcRFC and K cells was investigated. Antisera recognizing determinants of the HLA-A, -B, and -C series had no effect on FcRFC, while specific inhibition was observed with an antiserum reacting with determinants closely associated to HLA-DW2. This inhibitory effect was also demonstrated by the Fab' fragments. Specific inhibition of K cells was observed with all HLA antisera, but this effect was lost in the Fab' fragments. We concluded that the Fc receptor of FcRFC may be closely associated with products of the HLA-D region. This is analogous to the association between the Fc receptor and the Ia antigens on murine splenic B lymphocytes.

Binding Sites, Antibody

Human acute myelogenous leukemia antigens defined by simian antisera: evidence for leukemia-associated antigens distinct from immune response-associated alloantigens.

Leukemic blasts from a patient with acute myelogenous leukemia (AML) and peripheral blood T- and B-lymphocyte subpopulations from his genetically identical normal twin were analyzed with the use of the simian antiserum-defining AML antigens and a rabbit antiserum to immune response-associated (la)-like antigens. Blast cells from the patient consistently reacted with both reagents, whereas the B-lymphocyte populations from the patient's normal identical twin reacted only with the rabbit anti-la serum and in no instances reacted with the antiserum to AML cell antigens. Blast cells from the AML patient significantly stimulated the lymphocytes of his normal twin and his own remission leukocytes, whereas the cells from the normal twin failed to stimulate the cells of the patient. These results suggested the existence on AML cells of tumor-associated antigens that are distinct from various other well-characterized normal human alloantigens and differentiation antigens including B-cell antigens. Changes were reported in the expression of leukemia-associated antigens and Ia-like antigens on the cells of an AML patient undergoing chemotherapy as well as in the ability of the simian antisera to distinguish antigens specific for myeloid leukemias from lymphocytic types of leukemias.

Animals

Topographical distribution and association of tumor--associated antigens and their role in antigenicity in rat tumor cells.

The antigenicity of tumor-associated antigen (TAA) was compared between 3-methylcholanthrene-induced rat fibrosarcoma KMT-17 and Friend murine leukemia virus-infected KMT-17 (FV-KMT-17) cells. The antigenicity was classified into immunosensitivity and immunogenicity, and studied from the viewpoint of humoral immunity. The immunosensitivity to anti TAA antibodies increased by artificial infection of KMT-17 cells with Friend virus. The results suggested that an increase of lateral mobility of TAA on the cell surface contributes to the increase of immunosensitivity. Concerning the immunogenicity of TAA, an augmentation of anti-TAA antibody formation was demonstrated when FV-KMT-17 cells were used as the immunogen. In this case, a physical association between TAA and virus-associated antigen (VAA) was suggested to be very important to increase the immunogenicity of TAA.

Animals