Oxytocin Receptor Gene Research Articles

Environmental and Genetic Contributions to Attachment in Late Adolescence and Young Adulthood.

Adverse childhood experiences (ACEs) have been linked with attachment insecurity and psychopathology. However, some individuals remain securely attached and resilient following ACEs. Researchers have examined polymorphisms in the oxytocin receptor gene (OXTR), particularly rs53576, as a source of resilience, though examination of the biological mechanism by which rs53576 buffers the relation that would otherwise exist between ACEs and attachment insecurity is absent. The aim of the current study was to examine how ACEs interact with individual genetic and immune vulnerability to shape attachment security in older adolescents and young adults (n = 201). Moderated mediational models were tested in which ACEs acted as independent variables, attachment security acted as a dependent variable, inflammation (i.e., IL-6) was tested as a mediator, and rs53576 (i.e., AA, AG, GG genotypes) was tested as a moderator. Results indicated that physical abuse was significantly associated with decreased attachment security, with moderation by rs53576. A significant main effect of rs53576 on IL-6 was also noted. A similar pattern of results was evident across other ACEs and suggests that the effects of ACEs on attachment are buffered by the GG genotype. Association between GG and lower IL-6 suggests inflammation plays some role, though more research is needed.

R150S mutation in the human oxytocin receptor: Gain-of-function effects and implication in autism spectrum disorder

This study investigates the rs547238576 (R150S) missense variant in the oxytocin receptor (OXTR) gene, previously observed through screening of rare variants in Japanese individuals with autism spectrum disorders (ASD). Contrary to the anticipated loss-of-function, R150S exhibits gain-of-function effects, enhancing oxytocin (OXT) sensitivity, ligand-binding affinity, and OXT-induced Ca2+ mobilization in vitro. This suggests R150S may alter OXT signaling, potentially contributing to the excitatory/inhibitory imbalance seen in ASD and other psychiatric disorders. Our findings underscore the significance of genetic variations in OXTR on functional activity and highlight the necessity for population-specific genetic study and in vitro analysis to elucidate genetic susceptibilities to neuropsychiatric conditions.

Epistatic interactions between oxytocin- and dopamine-related genes and trust.

Trust is an essential human trait. Although research suggests that the interplay between oxytocinergic and dopaminergic systems affects trust formation, little research has focused on epistatic (i.e., gene by gene) interaction effects of oxytocin- and dopamine-related genes on trust. Using a sample of 348 adults (114 men), we aimed to investigate the associations between genetic variants in oxytocin- and dopamine-related genes and the general, neighborhood, and institutional trust with consideration of sex differences. Three-way interaction between oxytocin-related gene genotypes, dopamine-related genotypes, and sex was found for the oxytocin receptor gene (OXTR)rs1042778 and the Catechol-O-Methyltransferase gene (COMT) rs4680 genotypes (p = 0.02) and for OXTR rs2254298 and the dopamine D2 receptor gene (DRD2) rs1800497 genotypes (p = 0.01). Further sex-stratified analyses revealed that the interaction between OXTR rs1042778 and COMT rs4680 genotypes was associated with neighborhood trust among men (p = 0.0007). Also, the interaction between OXTR rs2254298 and DRD2 rs1800497 genotypes was associated with institutional trust among men (p = 0.005). Post-hoc analyses found that men with OXTR rs1042778 TG/TT and COMT rs4680 GG genotypes reported higher neighborhood trust than those with GG + AG/AA (B = 13.49, SE = 4.68, p = 0.02), TG/TT + AG/AA (B = 23.00, SE = 5.99, p = 0.001), and GG + GG (B = 18.53, SE = 5.25, p = 0.003). Similarly, men with OXTR rs2254298 AG/AA and DRD2 rs1800497 CC genotypes showed higher institutional trust than those with AG/AA + TT/TC (B = 15.67, SE = 5.30, p = 0.02). We could not find any interacting associations among women. While we note that our sample size and candidate gene approach have a potential risk of chance findings, our study provides an important foundation toward further exploration of sex-specific epistatic interaction effects of oxytocin- and dopamine-related genes on trust, indicating the importance of both systems in trust formation.

The oxytocinergic system and racial ingroup bias in empathic neural activity

Studies have indicated that the human brain exhibits a more robust neural empathic response towards individuals of the same racial ingroup than those of the outgroup. However, the impact of the oxytocinergic system on the dynamic connectivity between brain regions involved in racial ingroup bias in empathy (RIBE) and its implications for real-life social interaction intention remains unclear. To address this gap, we employed functional magnetic resonance imaging (fMRI) to investigate RIBE-modulated neural activities and the influence of the oxytocinergic system at both neural and behavioral levels. Participants homozygous for the A/A and G/G genotypes of the oxytocin receptor gene (OXTR) rs53576 polymorphism underwent scanning while making judgments about painful versus non-painful stimuli in same-race versus other-race scenarios following either oxytocin (OT) or placebo treatment. The results revealed greater activity in the anterior cingulate cortex (ACC) and anterior insula (AI) in response to same-race compared to other-race models in the G/G group but not in the A/A group. RIBE also modulated the connections between bilateral AI and the ACC, and the effect of OT on this modulatory effect was moderated by genotype rs53576 and interpersonal trust. Moreover, more extensive changes in AI-ACC connections were associated with higher levels of revenge intention in the low interpersonal trust group. Overall, our findings suggest a pivotal role of the oxytocinergic system in the RIBE-modulated neural activities and revenge intention in human interactions with the modulatory effect of interpersonal trust.This article is part of the Special Issue on “Empathic Pain”.

Study of the association between oxytocin receptor gene polymorphism, childhood adversity and negative symptoms of schizophrenia

Is known that the neurohormone oxytocin plays an important role in the pathogenesis of mental illness, and also models the relationship between stress factors, especially those acting in the early stages of development, and the development of mental disorders. Based on these data, we investigated the effects of the interaction of the environmental factor, which was considered the adversity of childhood (ND) and the oxytocin receptor (OXTR) genotypes in the polymorphic sites rs4686302 and rs7632287, on the severity of negative symptoms of schizophrenia. The study involved 592 patients with schizophrenia (headings F20. according to ICD-10). Information about the presence of ND was obtained from case histories and patient interviews. Analysis of covariance (GML) was used for statistical data processing; in post-hoc pairwise comparison, Tukey’s test was used. A significant effect of the interaction between ND and OXTR gene polymorphism rs7632287(G/A) on the severity of negative symptoms in patients with schizophrenia was revealed. In patients without ND, polymorphisms did not have a significant effect on the studied phenotype. Thus, our study showed for the first time that the rs7632287(G/A) polymorphism and ND have a mutual effect on the severity of negative symptoms of schizophrenia.

Effects of human-animal interaction on salivary and urinary oxytocin in children and dogs

Oxytocin pathways are hypothesized to play important roles in human-animal interactions and may contribute to some benefits of these interspecific social relationships. We explored the effects of naturalistic interactions between children and dogs on oxytocin release in both species, as well as associations between methylation of the oxytocin receptor gene (OXTRm), social behavior, and oxytocin response in this context. Children (N = 55) participated in a within-subjects design involving a) interaction with their pet dog, b) interaction with an unfamiliar dog, and c) a nonsocial control condition (solitary play). We used immunoassays to measure salivary and urinary oxytocin in both the children and dogs, behavioral coding to characterize dog-child interactions, and bisulfite sequencing to quantify methylation of the oxytocin receptor gene (N = 32 children). Child salivary oxytocin decreased moderately across time in all conditions, but the extent of this effect varied between conditions, with greater oxytocin output during interactions with dogs than the control condition. In the pet dog condition, children’s salivary oxytocin response was positively associated with the duration of visual co-orientation between the child and dog. Child urinary oxytocin did not deviate substantially from baseline in any condition. Children with higher levels of OXTRm had greater oxytocin output during interactions with their pet dogs, but lower oxytocin output in the control condition, and engaged in lower levels of affectionate interaction with dogs across conditions. Children’s pet dogs exhibited increases in salivary oxytocin, but we observed the opposite pattern in the unfamiliar dog, who exhibited decreases in both urinary and salivary oxytocin on average. Collectively, our results support the hypothesis that oxytocin pathways may shape and respond to social interactions between children and dogs, highlighting an important role for companion animals in child development.

The interplay between borderline personality disorder and oxytocin: a systematic narrative review on possible contribution and treatment options.

Borderline personality disorder (BPD) is a complex mental health condition marked by instability in mood, relationships, self-image, and behavior. Individuals with BPD often struggle with intense emotions, impulsivity, and maintaining stable relationships. Oxytocin, known as the "love hormone" or "bonding hormone," plays a crucial role in social bonding, trust, empathy, and emotional regulation and its dysregulation may contribute to BPD difficulties. This systematic review aims to analyze existing literature, examining the intricate interplay and encouraging future research and treatment strategies. A systematic search of Literature in PubMed, Embase and Psychinfo, without any language or time restriction, was performed until March 2024 combining thesaurus and free-search indexing terms related to "borderline personality disorder" and "oxytocin", producing 310 results (77 in PubMed, 166 in Embase and 67 in Psychinfo). Ninety-four full texts were analyzed, and 70 articles were included in qualitative analysis. Oxytocin may influence attachment styles, parental behaviors, and stress responses, particularly in individuals with a history of childhood trauma. The interaction between oxytocin, genetics, early life experiences, and environmental factors contributes to the complexity of BPD. Genetic variations in the oxytocin receptor gene may influence social and emotional abilities and contribute to the development of psychopathology. Additionally, early adverse experiences, such as childhood maltreatment, can alter oxytocin functioning, impacting social cognition and emotional regulation.However, oxytocin's role in BPD treatment remains uncertain, with some studies suggesting potential benefits for specific symptoms like social threat avoidance, while others indicate adverse effects on nonverbal behavior and mentalizing. Understanding oxytocin's role in BPD offers insights into potential therapeutic interventions. While oxytocin-based treatments may hold promise for addressing specific symptoms, further research is needed.

Exploring the role of OXTR gene methylation in attachment development: A longitudinal study.

The current study explored longitudinally whether oxytocin receptor gene methylation (OXTRm) changes moderated the association between parental sensitivity changes and children'sattachment changes over three waves. Six hundred six Flemish children (10-12 years, 42.8%-44.8% boys) completed attachment measures and provided salivary OXTRm data on seven CpG sites. Their parents reported their sensitive parenting. Results suggest that OXTRm changes hardly link to attachment (in)security changes after the age of 10. Some support was found for interaction effects between parental sensitivity changes and OXTRm changes on attachment changes over time. Effects suggest that for children with increased OXTRm in the promotor region and decreased methylation in the inhibitor region over time, increased parental sensitivity was associated with increased secure attachment and decreased insecure attachment over time.

A Common OXTR Risk Variant Alters Regulation of Gene Expression by DNA Hydroxymethylation in Pregnant Human Myometrium

Postpartum hemorrhage, or excessive bleeding after birth, is a leading cause of maternal morbidity. A major cause of postpartum hemorrhage is uterine atony, tiring of the uterus which leads to ineffective contractions. Uterine contractions depend on oxytocin signaling in the myometrium, which in turn depends on expression of the oxytocin receptor (OXTR). Both genetic and epigenetic factors related to the oxytocin receptor are associated with risk of postpartum hemorrhage, but a mechanism relating these factors to oxytocin receptor activity in myometrium remains unclear. We report a genetic by epigenetic interaction whereby the relationship between DNA hydroxymethylation and OXTR gene expression depends on a common OXTR gene variant (rs53576). We also provide evidence that a similar genetic by epigenetic interaction using blood-derived DNA methylation is associated with relevant clinical outcomes: quantity of oxytocin administration and odds for postpartum hemorrhage. These results provide new avenues for predicting how women will respond to pharmacological agents in the prevention and treatment of postpartum hemorrhage.

Oxytocin receptor gene polymorphism (rs53576) and depressive symptoms: a systematic review and meta-analysis

Oxytocin receptor gene polymorphism (rs53576) and depressive symptoms: a systematic review and meta-analysis

Assessment of Some Physiological, Immunological and Molecular Biomarkers in Sample of Iraqi Women Undergoing Caesarean Section and Normal Delivery

Pregnancy and delivery are physiological conditions that are marked by abrupt alterations to hormones, immunological and molecular characters. The current study aimed to evaluate oxytocin (OT), prolactin (PRL), cortisol and insulin growth factor-2 (IGF-2) levels as physiological biomarkers; programmed cell death protein-1 (PD-1), programmed cell death ligand-1 (PD-L1),interleukin-6 (IL-6) as immunological biomarkers, and single nucleotide polymorphisms (SNPs; rs53576 and rs2254298) of oxytocin receptor gene OXTR as molecular factors in samples of Iraqi women undergoing caesarean section (CS) and normal delivery (ND). Blood samples were collected from 96 pregnant women at term with ages ranging between 16-43 years. Regarding the physiological biomarkers, the study findings indicated that the change in OT, cortisol and IGF-2 between CS and ND groups was not significant, While the PRL level indicated a highly significant (P≤0.001) decrease in the CS group, especially in comparison with the ND group. Immunological biomarkers demonstrated a significant (P≤05) elevation for PD-1 as well as for PD-L1 in the CS group as compared to the ND group. However, PD-1/PD-L1 ratio revealed a high significant (P≤0.001) rise in CS compared with ND. The IL-6 results revealed a significant (P≤0.001) reduction in the CS groups compared to the ND group. And regarding the SNP of OXTR (rs53576), the findings revealed no notable association in genotypes CC, TC and TT between both groups. In addition, the mutant C allele and the wild T allele revealed no significant association between CS and ND groups [OR=1.26 (0.68-2.3%)]. The SNP results of OXTR (rs2254298) showed a high positive association (P≤0.001) in genotypes GG, AG and AA between CS and ND groups. Also, the mutant G allele and the wild A allele revealed high significance (P≤0.001) between both groups [OR=5.3 (2.8-9.76%)].

A dog's life: Early life histories influence methylation of glucocorticoid (NR3C1) and oxytocin (OXTR) receptor genes, cortisol levels, and attachment styles.

Early life deprivation and stress can contribute to life-long, problematic consequences, including epigenetic variations related to behavior and health. Domestic dogs share human environments and social-cognitive traits, making them a promising comparative model to examine developmental plasticity. We examined 47 owner-dog dyads, including dogs rescued from abusive or neglectful environments, and matched control dogs for changes in DNA methylation of glucocorticoid (NR3C1) and oxytocin (OXTR) receptor genes previously shown to be affected by early life stress in other species including humans. We used an attachment paradigm, which included a separation event to examine cortisol levels and owner-dog attachment styles. Overall, dogs with adverse histories had different NR3C1 methylation patterns as a function of age and less OXTR methylation than comparison dogs. Dogs with adverse histories did not differ in their cortisol change from baseline to poststressor from comparison dogs, but the change in cortisol was associated with NR3C1 methylation. In addition, dogs with a history of early life stress had more insecure attachment styles; for every unit increase of OXTR methylation, the odds increased for insecure attachment style. This study demonstrates that adverse life histories lead to methylation differences, resulting in the hypothalamic-pituitary-adrenal (HPA) axis's dysregulation and differences in behavioral phenotypes.

Study of the Association between Oxytocin Receptor Gene Polymorphism, Childhood Adversity, and Negative Symptoms of Schizophrenia

Study of the Association between Oxytocin Receptor Gene Polymorphism, Childhood Adversity, and Negative Symptoms of Schizophrenia

Cinnamic acid promotes elongation of hair peg-like sprouting in hair follicle organoids via oxytocin receptor activation

Considerable global demand exists for the development of novel drugs for the treatment of alopecia. A recent report demonstrated that oxytocin promotes hair growth activity in human dermal papilla (DP) cells; however, its application in drugs or cosmetic products is challenging because rapid degradation and relatively large molecular weight prevent long-term topical administration on the scalp. Here, we examined cinnamic acid, a small molecule activator for oxytocin receptor (OXTR) expression. Treatment with cinnamic acid led to upregulation of OXTR and trichogenic gene expression in human DP cells. Furthermore, inhibition of OXTR with an antagonist, L-371,257, suppressed hair growth-related gene expression in DP cells. These findings suggest that cinnamic acid enhances the hair growth ability of DP cells via oxytocin signaling. Additionally, we tested the hair growth-promoting effects of cinnamic acid using hair follicle organoids in vitro and observed that cinnamic acid significantly promoted the growth of hair peg-like sprouting. These promising results may be useful for developing hair growth-promoting products targeting oxytocin.

Selective alterations of endocannabinoid system genes expression in obsessive compulsive disorder

Obsessive Compulsive Disorder (OCD) is listed as one of the top 10 most disabling neuropsychiatric conditions in the world. The neurobiology of OCD has not been completely understood and efforts are needed in order to develop new treatments. Beside the classical neurotransmitter systems and signalling pathways implicated in OCD, the possible involvement of the endocannabinoid system (ECS) has emerged in pathophysiology of OCD. We report here selective downregulation of the genes coding for enzymes allowing the synthesis of the endocannabinoids. We found reduced DAGLα and NAPE-PLD in blood samples of individuals with OCD (when compared to healthy controls) as well as in the amygdala complex and prefrontal cortex of dopamine transporter (DAT) heterozygous rats, manifesting compulsive behaviours. Also mRNA levels of the genes coding for cannabinoid receptors type 1 and type 2 resulted downregulated, respectively in the rat amygdala and in human blood. Moreover, NAPE-PLD changes in gene expression resulted to be associated with an increase in DNA methylation at gene promoter, and the modulation of this gene in OCD appears to be correlated to the progression of the disease. Finally, the alterations observed in ECS genes expression appears to be correlated with the modulation in oxytocin receptor gene expression, consistently with what recently reported. Overall, we confirm here a role for ECS in OCD at both preclinical and clinical level. Many potential biomarkers are suggested among its components, in particular NAPE-PLD, that might be of help for a prompt and clear diagnosis.

Chronic oxytocin improves neural decoupling at rest in children with autism: an exploratory RCT.

Shifts in peak frequencies of oscillatory neural rhythms are put forward as a principal mechanism by which cross-frequency coupling/decoupling is implemented in the brain. During active neural processing, functional integration is facilitated through transitory formations of "harmonic" cross-frequency couplings, whereas "nonharmonic" decoupling among neural oscillatory rhythms is postulated to characterize the resting, default state of the brain, minimizing the occurrence of spurious, noisy, background couplings. Within this exploratory, randomized, placebo-controlled trial, we assessed whether the transient occurrence of nonharmonic and harmonic relationships between peak-frequencies in the alpha (8-14 Hz) and theta (4-8 Hz) bands is impacted by intranasal administration of oxytocin, a neuromodulator implicated in improving homeostasis and reducing stress/anxiety. To do so, resting-state electroencephalography was acquired before and after 4 weeks of oxytocin administration (12 IU twice-daily) in children with autism spectrum disorder (8-12 years, n = 33 oxytocin; n = 34 placebo). At the baseline, neural assessments of children with autism were compared with those of a matched cohort of children without autism (n = 40). Compared to nonautistic peers, autistic children displayed a lower incidence of nonharmonic alpha-theta cross-frequency decoupling, indicating a higher incidence of spurious "noisy" coupling in their resting brain (p = .001). Dimensionally, increased neural coupling was associated with more social difficulties (p = .002) and lower activity of the parasympathetic "rest & digest" branch of the autonomic nervous system (p = .018), indexed with high-frequency heart-rate-variability. Notably, after oxytocin administration, the transient formation of nonharmonic cross-frequency configurations was increased in the cohort of autistic children (p < .001), indicating a beneficial effect of oxytocin on reducing spurious cross-frequency-interactions. Furthermore, parallel epigenetics changes of the oxytocin receptor gene indicated that the neural effects were likely mediated by changes in endogenous oxytocinergic signaling (p = .006). Chronic oxytocin induced important homeostatic changes in the resting-state intrinsic neural frequency architecture, reflective of reduced noisy oscillatory couplings and improved signal-to-noise properties.

Fatty Acid Amide Hydrolase and Cannabinoid Receptor Type 1 Genes Regulation is Modulated by Social Isolation in Rats.

Social isolation is a state of lack of social connections, involving the modulation of different molecular signalling cascades and associated with high risk of mental health issues. To investigate if and how gene expression is modulated by social experience at the central level, we analyzed the effects of 5weeks of social isolation in rats focusing on endocannabinoid system genes transcription in key brain regions involved in emotional control. We observed selective reduction in mRNA levels for fatty acid amide hydrolase (Faah) and cannabinoid receptor type 1 (Cnr1) genes in the amygdala complex and of Cnr1 in the prefrontal cortex of socially isolated rats when compared to controls, and these changes appear to be partially driven by trimethylation of Lysine 27 and acetylation of Lysine 9 at Histone 3. The alterations of Cnr1 transcriptional regulation result also directly correlated with those of oxytocin receptor gene. We here suggest that to counteract the effects of SI, it is of relevance to restore the endocannabinoid system homeostasis via the use of environmental triggers able to revert those epigenetic mechanisms accounting for the alterations observed.

Cumulative Genetic Scores Interact with Maternal and Paternal Parenting in Predicting Parent-Adolescent Cohesion and Conflict.

Previous research concerning the interplay between genetics and parenting in the development of the parent-child relationship during adolescence has been extremely scarce, predominantly adopting single-gene designs. This limited body of work has largely overlooked the distinct effects of maternal and paternal roles, as well as potential gender differences. Additionally, existing gene-by-environment (G × E) studies have mainly concentrated on adverse environmental factors and associated negative outcomes, somewhat neglecting positive environments and outcomes. The present study examined the interactions of cumulative genetic scores (CGS, dopamine receptor D2 TaqIA and oxytocin receptor gene rs53576 polymorphisms) with both positive and negative parenting on parent-adolescent cohesion and conflict. Furthermore, this study aimed to ascertain with which gene-environment model the potential G × E interactions would align. A total of 745 Chinese Han adolescents (Mage = 13.36 ± 0.96 years; 46.8% girls) from grades 7 to 9 participated in this study. Results revealed a significant effect of CGS and negative maternal parenting on mother-adolescent conflict among males, consistent with the weak differential susceptibility model. As CGS increased, the effects of negative maternal parenting on mother-son conflict were magnified. These findings have implications for the timing and focus of interventions aimed at improving parent-adolescent relationships.

The role of oxytocin receptor gene variants in appetitive aggression: A study in a South African male sample

AbstractChronic exposure to trauma and violence can promote aggressive behavior. Oxytocin and variants in the oxytocin receptor (OXTR) gene may play a role in the etiology of proactive, that is, goal‐oriented instrumental aggression, or reactive aggression, which typically occurs in response to emotionally triggering situations. The current study builds on previous findings that experienced and witnessed trauma in childhood predicts higher levels of appetitive aggression, a form of proactive aggression characterized by the enjoyment of participating in violent behavior. The current study explores the role of OXTR rs2254298 and rs53576 variants in appetitive and reactive aggression. Adult males living in Cape Town, South Africa, and at risk for violent behavior completed the Appetitive Aggression Scale (AAS) and Buss–Perry Aggression Questionnaire (BPAQ). OXTR rs2254298 and rs53576 were successfully genotyped via restriction fragment length polymorphism (RFLP) analysis in 238 and 239 participants, respectively. Regression analysis showed that rs2254298 G/G and A/G genotypes and the rs53576 A/G genotype were significantly associated with lower AAS scores (p &lt; .001) compared to the A/A genotype. Additionally, genotype interaction analyses conducted in 232 participants, found that the combination of rs2254298 A/G and rs53576 G/G genotypes produced opposite effects on appetitive and reactive aggression. Specifically, this combination was associated with a 0.29‐point increase in AAS scores (p = .032) and a 0.13‐point decrease in BPAQ scores (p = .037) when compared to A‐allele homozygosity for both variants. These results suggest that genetic variation in a signaling system involved in influencing environmental and social salience may contribute to appetitive aggression.

Quantification of surface-localized and total oxytocin receptor in myometrial smooth muscle cells

Oxytocin acts through the oxytocin receptor (OXTR) to modulate uterine contractility. We previously identified OXTR genetic variants and showed that, in HEK293T cells, two of the OXTR protein variants localized to the cell surface less than wild-type OXTR. Here, we sought to measure OXTR in the more native human myometrial smooth muscle cell (HMSMC) line on both the cell-surface and across the whole cell, and used CRISPR editing to add an HA tag to the endogenous OXTR gene for anti-HA measurement. Quantitative flow cytometry revealed that these cells possessed 55,000 ± 3200 total OXTRs and 4900 ± 390 cell-surface OXTRs per cell. To identify any differential wild-type versus variant localization, we transiently transfected HMSMCs to exogenously express wild-type or variant OXTR with HA and green fluorescent protein tags. Total protein expression of wild-type OXTR and all tested variants were similar. However, the two variants with lower surface localization in HEK293T cells also presented lower surface localization in HMSMCs. Overall, we confirm the differential surface localization of variant OXTR in a more native cell type, and further demonstrate that the quantitative flow cytometry technique is adaptable to whole-cell measurements.