Leaf Surface Wax Chemicals in Trichosanthes anguina (Cucurbitaceae) Cultivars Mediating Short-Range Attraction and Oviposition in Diaphania indica.

Larval Diaphania indica (Saunders) (Lepidoptera: Crambidae) cause complete defoliation of Trichosanthes anguina L. and reduce crop yield in India. Females lay eggs on the leaf surface, and therefore leaf surface waxes are potentially involved in host selection. Alkanes and free fatty acids are the major constituents of leaf surface waxes, so a study was conducted to determine whether these wax constituents from three T. anguina cultivars (MNSR-1, Baruipur Long, and Polo No.1) could act as short-range attractants and oviposition stimulants in D. indica females. Twenty n-alkanes from n-C14 to n-C36 and 13 free fatty acids from C12:0 to C21:0 were detected in the leaf surface waxes of these cultivars. Heptadecane and stearic acid were predominant among n-alkanes and free fatty acids, respectively, in these cultivars. Females showed attraction towards one leaf equivalent surface wax of each of these cultivars against solvent controls (petroleum ether) in Y-tube olfactometer bioassays. A synthetic blend of heptadecane, eicosane, hexacosane, and stearic acid, a synthetic blend of hexacosane and stearic acid, and a synthetic blend of pentadecane and stearic acid comparable to amounts present in one leaf equivalent surface wax of MNSR-1, Baruipur Long, and Polo No.1, respectively, were short-range attractants and oviposition stimulants in D. indica. Female egg laying responses were similar to each of these blends, providing information that could be used to developing baited traps in integrated pest management (IPM) programs.

Isolation of Pure Individual Fatty Acids from Chicken Skin Using Supercritical CO2 Extractor or Cooling Centrifuge.

Chicken skin -a poultry meat industries waste- has been used in this work as a source for the production of pure free fatty acids. Chicken skin fat was extracted using dry rendering method. Physical and chemical parameters of that fat were determined. Also, its fatty acids composition has been identified by GC-MS after its esterification as oleic, palmitic, linoleic, stearic, myristic, lauric, linolenic, behenic, arachidonic, arachidic, palmitoleic, and paullinic acids, and others as traces. The extracted fat was then hydrolyzed into mixture of free fatty acids and glycerol, the free fatty acid mixture was separated, then it was cooled in order to separate saturated and unsaturated fatty acids from each other. Oleic, Palmitic, Linoleic and Stearic Acids were extracted individually in pure form using supercritical CO2 extractor. Moreover, oleic, linoleic, palmitoleic, linolenic, and paullinic acids were extracted individually in pure form using cooling centrifuge sigma 3-18KS. All of the separated individual fatty acids were confirmed according to their melting point, GC-MS after esterification, elemental analysis and mass spectrometry (ms) of the corresponding methyl ester in order to detect the corresponding molecular ion peak. Therefore, these new two methods could afford the very expensive pure fatty acids with a low cast.

Volatile Profile in Yogurt Obtained from Saanen Goats Fed with Olive Leaves.

The aim of this study was to evaluate the development of volatile compounds in yogurt samples obtained from goats fed a dietary supplementation with olive leaves (OL). For this purpose, thirty Saanen goats were divided into two homogeneous groups of 15 goats each: a control group that received a standard diet (CG) and an experimental group whose diet was supplemented with olive leaves (OLG). The trial lasted 28 days, at the end of which the milk of each group was collected and used for yogurt production. Immediately after production, and after 7 days of storage at 4 °C in the absence of light, the yogurt samples were characterized in terms of fatty acid profile, oxidative stability and volatile compounds by the solid-phase microextraction (SPME)-GC/MS technique. Dietary OL supplementation positively affected the fatty acid composition, inducing a significant increase in the relative proportion of unsaturated fatty acids, mainly oleic acid (C18:1 cis9) and linolenic acid (C18:3). With regard to the volatile profile, both in fresh and yogurt samples stored for 7 days, the OL supplementation induced an increase in free fatty acids, probably due to an increase in lipolysis carried out by microbial and endogenous milk enzymes. Specifically, the largest variations were found for C6, C7, C8 and C10 free fatty acids. In the same samples, a significant decrease in aldehydes, mainly heptanal and nonanal, was also detected, supporting-at least in part-an improvement in the oxidative stability. Moreover, alcohols, esters and ketones appeared lower in OLG samples, while no significant variations were observed for lactones. These findings suggest the positive role of dietary OL supplementation in the production of goats' milk yogurt, with characteristics potentially indicative of an improvement in nutritional properties and flavor.

Profiling free fatty acids in edible oils via magnetic dispersive extraction and comprehensive two-dimensional gas chromatography-mass spectrometry.

The analysis of free fatty acids (FFAs) in edible oils can provide important information for quality control and oil authentication. Herein, we report the comprehensive profiling of FFAs in edible oils via magnetic dispersive extraction combined with comprehensive two-dimensional gas chromatography-mass spectrometry (GC × GC-MS). A magnetic extractant was designed for dispersive extraction of FFAs. The extraction conditions were carefully optimized. To assess the extraction method, we first use the method for analysis of 7 targeted FFAs. The limits of detection range from 5.6 to 25.8 ng g-1, and the recoveries in oil samples are 81%-107%. We then performed comprehensive profiling of untargeted FFAs in oil by combining the extraction method with GC × GC-MS. A total of 64 FFAs were identified positively or putatively. The proposed method can provide FFA fingerprint data to guide the processing, storage and authentication of edible oils.

Recent Developments of Useful MALDI Matrices for the Mass Spectrometric Characterization of Lipids.

Matrix-assisted laser desorption/ionization (MALDI) is one of the most successful "soft" ionization methods in the field of mass spectrometry and enables the analysis of a broad range of molecules, including lipids. Although the details of the ionization process are still unknown, the importance of the matrix is commonly accepted. Both, the development of and the search for useful matrices was, and still is, an empirical process, since properties like vacuum stability, high absorption at the laser wavelength, etc. have to be fulfilled by a compound to become a useful matrix. This review provides a survey of successfully used MALDI matrices for the lipid analyses of complex biological samples. The advantages and drawbacks of the established organic matrix molecules (cinnamic or benzoic acid derivatives), liquid crystalline matrices, and mixtures of common matrices will be discussed. Furthermore, we will deal with nanocrystalline matrices, which are most suitable to analyze small molecules, such as free fatty acids. It will be shown that the analysis of mixtures and the quantitative analysis of small molecules can be easily performed if the matrix is carefully selected. Finally, some basic principles of how useful matrix compounds can be "designed" de novo will be introduced.

Preparation of Pinolenic Acid Concentrates from Pine Nut Oil Fatty Acids by Solvent Fractionation.

Pinolenic acid (PLA), which is a fatty acid (FA) exclusively found in the oils of edible pine nuts, has an appetite-suppression effect, thereby being effective to reduce body weight in humans. PLA concentrates would be suitable for use in functional foods and nutraceuticals due to the health benefits of PLA. PLA concentrates were prepared from free FA (FFA) obtained from pine nut oil using solvent fractionation. Siberian pine nut oil containing 18.3 wt% PLA was used as the starting material for the fractionation. The fractionation was performed in n-hexane at ultra-low temperatures down to -85°C. The PLA concentrates produced under the optimal conditions established in this study (temperature, -85°C; n-hexane-to-FFA ratio (v/w), 30:1; fractionation time, 36 h) contained 69.8 wt% PLA. The yield of PLA was 77.4 wt% of the initial PLA weight in the FFA. These results suggest that solvent fractionation is a more effective approach to prepare PLA concentrates with higher PLA contents at a particular yield of PLA than published methods using urea crystallization (e.g., PLA content = ~47 wt%, yield of PLA = ~77 wt%, Woo et al. (2016)) or lipase-catalyzed reactions (e.g., PLA content = ~30 wt%, yield of PLA = ~61 wt%, Lee et al. (2011)). The resulting PLA concentrates contained 11 of the 12 different species of FA present in the FFA, thereby indicating that the PLA concentrates prepared by solvent fractionation have more diverse FA profiles than those prepared by urea crystallization (e.g., 7 species of FA, Woo et al. (2016)).

Lipidomic profiling reveals free fatty acid alterations in plasma from patients with atrial fibrillation.

Atrial fibrillation (AF) is the most common cardiac arrhythmia, and its incidence is increasing worldwide. One method used to restore sinus rhythm is direct current cardioversion (DCCV). Despite the high success rate of DCCV, AF typically recurs within the first 2 weeks. However, our understanding of the pathophysiology of AF recurrence, incidence, and progression are highly limited. Lipidomic profiling was applied to identify altered lipids in plasma from patients with AF using ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry coupled with multivariate statistical analysis. Partial least-squares discriminant analysis revealed a clear separation between AF patients and healthy controls. The levels of several lipid species, including fatty acids and phospholipids, were different between AF patients and healthy controls, indicating that oxidative stress and inflammation are associated with the pathogenesis of AF. Similar patterns were also detected between recurrent and non-recurrent AF patients. These results suggest that the elevated saturated fatty acid and reduced polyunsaturated fatty acid levels in AF patients may be associated with enhanced inflammation and that free fatty acid levels may play a crucial role in the development and progression of AF.

A New Strategy to Refine Crude Indian Sardine Oil.

Current work aims to develop a refining process for removing phospholipids, free fatty acids (FFA), and metal ions without affecting n-3 polyunsaturated fatty acid (n-3 PUFA) esters present in the crude Indian sardine oil. Sardine oil was subjected to degumming with various acids (orthophosphoric acid, acetic acid, and lactic acid), conventional and membrane assisted deacidification using various solvents (methanol, ethanol, propanol and butanol) and bleaching with bleaching agents (GAC, activated earth and bentonite) and all the process parameters were further optimized. Degumming with 5%(w/w) ortho phosphoric acid, two stage solvent extraction with methanol at 1:1 (w/w) in each stage and bleaching with 3% (w/w) activated charcoal loading, at 80ºC for 10 minutes resulted in the reduction of phospholipid content to 5.66 ppm from 612.66 ppm, FFA to 0.56% from 5.64% with the complete removal of iron and mercury. Under these conditions, the obtained bleached oil showed an enhancement of n-3 PUFA from 16.39 % (11.19 Eicosapentaenoic acid (EPA) + 5.20 Docosahexaenoic acid (DHA)) to 17.91 % (11.81 EPA + 6.1 DHA). Replacing conventional solvent extraction with membrane deacidification using microporous, hydrophobic polytetrafluoroethylene membrane (PTFE), resulted in a lesser solvent residue (0.25% (w/w)) in the deacidified oil. In view of lack of reports on refining of n-3 PUFA rich marine oils without concomitant loss of n-3 PUFA, this report is significant.

Vacuum-assisted headspace-solid phase microextraction for determining volatile free fatty acids and phenols. Investigations on the effect of pressure on competitive adsorption phenomena in a multicomponent system.

This work proposes a new vacuum headspace solid-phase microextraction (Vac-HSSPME) method combined to gas chromatography-flame ionization detection for the determination of free fatty acids (FFAs) and phenols. All target analytes of the multicomponent solution were volatiles but their low Henry's Law constants rendered them amenable to Vac-HSSPME. The ability of a new and easy to construct Vac-HSSPME sampler to maintain low-pressure conditions for extended sampling times was concurrently demonstrated. Vac-HSSPME and regular HSSPME methods were independently optimized and the results were compared at all times. The performances of four commercial SPME fibers and two polymeric ionic liquid (PIL)-based SPME fibers were evaluated and the best overall results were obtained with the adsorbent-type CAR/PDMS fiber. For the concentrations used here, competitive displacement became more intense for the smaller and more volatile analytes of the multi-component solution when lowering the sampling pressure. The extraction time profiles showed that Vac-HSSPME had a dramatic positive effect on extraction kinetics. The local maxima of adsorbed analytes recorded with Vac-HSSPME occurred faster, but were always lower than that with regular HSSPME due to the faster analyte-loading from the multicomponent solution. Increasing the sampling temperature during Vac-HSSPME reduced the extraction efficiency of smaller analytes due to the enhancement in water molecule collisions with the fiber. This effect was not recorded for the larger phenolic compounds. Based on the optimum values selected, Vac-HSSPME required a shorter extraction time and milder sampling conditions than regular HSSPME: 20 min and 35 °C for Vac-HSSPME versus 40 min and 45 °C for regular HSSPME. The performance of the optimized Vac-HSSPME and regular HSSPME procedures were assessed and Vac-HSSPME method proved to be more sensitive, with lower limits of detection (from 0.14 to 13 µg L-1), and better intra-day precision (relative standard deviations values < 10% at the lowest spiked level) than regular HSSPME for almost all target analytes. The proposed Vac-HSSPME method was successfully applied to quantify FFAs and phenols in milk and milk derivatives samples.

Characterization of Palm Fatty Acid Distillate of Different Oil Processing Industries of Pakistan.

Palm fatty acid distillate (PFAD) is cheap and valuable byproduct of edible oil processing industries. This study was designed to characterize PFAD collected from different local oil industries. AOCS methods were used for the determination of physicochemical parameters such as free fatty acid (FFA), saponification value (SV), iodine value (IV), peroxide value (PV) and moisture content. Fatty acid composition was analyzed using GC-MS. Moisture content of samples was found to be in the range between 0.06-7.50%, while FFA, SV, IV and PV were found to be 65.70-94.68%, 195.23-219.64 mg KOH/g, 38.49- 63.10 g I2/100 g, 1.09-16.50 meq/kg, respectively. Mean value of fatty acids in PFAD was found as 0.04% lauric, 0.42% myristic, 41.25% palmitic, 7.29% stearic, 41.58% oleic, 8.95 % linoleic, 0.04% eicosenoic, 0.27% arachidic, 0.07% docosanoic, and 0.05% tetracosanoic acid, respectively. Palmitic acid was found as dominant saturated fatty acid 38.63-45.30%, whereas oleic acid C18:1 n9 was major unsaturated fatty acid 33.54-44.05 % in PFAD.

Selective elimination of the free fatty acid fraction from esterified fatty acids in rat plasma through chemical derivatization and immobilization on amino functionalized silica nano-particles.

A high throughput and low cost approach to separate free fatty acids (FFAs) from phospholipid and acylglycerols (esterified fatty acids, EFAs) has been demonstrated, which may be widely used as a sample preparation method in the metabolomics and lipid research. The optimal conditions for FFAs reacting with N-hydroxysuccinimide (NHS) only need 10min at room temperature to obtain a 93.5% yield of FFAs-NHS ester. The rest 6% FFA transformed into N-cyclohexyl-fatty acid-amide which is stable to methyl esterification adopted for fatty acids analysis. 10min are taken for FFAs-NHS ester to react with amino functionalized silica nanoparticles to immobilize the FFAs. The separation of FFAs from EFAs could be carried out readily by centrifugation. The whole process including derivatization, immobilization, and centrifugation takes less than 40min. Much more accurate fatty acids composition of rat plasma EFAs could be obtained by this approach than the previous reported methods.

Direct Derivatization vs Aqueous Extraction Methods of Fecal Free Fatty Acids for GC-MS Analysis.

A comprehensive and accurate determination of free fatty acids (FFA) is required for fecal metabolomic investigations. The present study compares three aqueous extraction methods (1) ULTRA-TURRAX(®), (2) whirl mixing and (3) basic ULTRA-TURRAX extraction of fecal FFA with a direct derivatization approach using ethyl chloroformate as the derivatization reagent before determination by gas chromatography-mass spectrometry. The direct derivatization method resulted in significantly higher estimations (P < 0.01) of short- and long-chain fatty acids than was the case when applying the aqueous extraction methods using ULTRA-TURRAX, whirl mixing, or basic ULTRA-TURRAX extraction before the derivatization step. Thus, avoiding an aqueous extraction before derivatization reduces the loss of volatile short-chain FFA and the less water-soluble long-chain FFA.

Production of biodiesel from vegetable oil and microalgae by fatty acid extraction and enzymatic esterification.

The aim of this work was to obtain biodiesel (methyl esters) from the saponifiable lipids (SLs) fraction of the microalga Nannochloropsis gaditana, whose biomass dry weight contains 12.1 wt% of these lipids. SLs were extracted from the microalga as free fatty acids (FFAs) for subsequent transformation to methyl esters (biodiesel) by enzymatic esterification. Extraction as FFAs rather than as SLs allows them to be obtained with higher purity. Microalgal FFAs were obtained by direct saponification of lipids in the biomass and subsequent extraction-purification with hexane. Esterification of FFAs with methanol was catalysed by lipase Novozym 435 from Candida antarctica. Stability studies of this lipase in the operational conditions showed that the esterification degree (ED) attained with the same batch of lipase remained constant over six reaction cycles (36 h total reaction time). The optimal conditions attained for 4 g of FFAs were 25°C, 200 rpm, methanol/FFA molar ratio of 1.5:1, Novozym 435/FFA ratio of 0.025:1 w/w and 4 h reaction time. In these conditions the ED attained was 92.6%, producing a biodiesel with 83 wt% purity from microalgal FFAs. Several experimental scales were tested (from 4 to 40 g FFAs), and in all cases similar EDs were obtained.

[Biological activity of lipids and photosynthetic pigments of Sargassum pallidum C. Agardh].

The biological activity of lipids and photosynthetic pigments of the kelp Sargassum pallidum (Turner) C. Agardh has been studied. Free fatty acids and their esters demonstrated considerable antimicrobial activity against bacteria (Staphylococcus aureus[ital] and Escherichia coli), yeast-like fungi (Candida albicans), and opportunistic pathogenic (Aspergilius niger) and phytopathogenic (Fusarium oxysporum, and Septoria glycines) fungi. Glyceroglycolipids and neutral lipids demonstrated moderate activity. Fucoxanthin and chlorophylls weakly suppressed the growth of microorganisms. None of the studied substances demonstrated activity against Ehrlich's carcinoma. It was shown that the season of weed harvesting affected both antimicrobial and hemolytic activities of different lipids due to changes in their fatty acid composition.

Hydrothermal treatment of oleaginous yeast for the recovery of free fatty acids for use in advanced biofuel production.

Microbial oils hold great potential as a suitable feedstock for the renewable production of biofuels. Specifically, the use of oleaginous yeasts offers several advantages related to cultivation and quality of lipid products. However, one of the major bottlenecks for large-scale production of yeast oils is found in the lipid extraction process. This work investigated the hydrothermal treatment of oleaginous yeast for hydrolysis and lipid extraction resulting in fatty acids used for biofuel production. The oleaginous yeast, Cryptococcus curvatus, was grown in 5 L bioreactors and the biomass slurry with 53±4% lipid content (dry weight basis) was treated at 280 °C for 1h with an initial pressure of 500 psi in batch stainless steel reactors. The hydrolysis product was separated and each of the resulting streams was further characterized. The hexane soluble fraction contained fatty acids from the hydrolysis of yeast triacylglycerides, and was low in nitrogen and minerals and could be directly integrated as feedstock into pyrolysis processing to produce biofuels. The proposed hydrothermal treatment addresses some current technological bottlenecks associated with traditional methodologies such as dewatering, oil extraction and co-product utilization. It also enhances the feasibility of using microbial biomass for production of renewable fuels and chemicals.

Effects of anionic surfactant on extraction of free fatty acid from Chlorella vulgaris.

Microalgal lipid with a high free fatty acid (FFA) content was directly extracted from Chlorella vulgaris, using SDBS, in an acid-catalyzed hot-water extraction process. The total fatty acid content of C. vulgaris was 296.0 mg/g cell. Under the 1.0% sulfuric acid, 0.4% SDBS conditions, the FFA content of the lipid increased to 96.7%, and the lipid-extraction yield was 248.4 mg/g cell. Under the 2.0% sulfuric acid, 0.2% SDBS conditions, the FFA content of the lipid was 96.1%, and the lipid-extraction yield was 266.0mg/g cell. Whereas the FAME content of the microalgal lipid extracted by hexane-methanol was 76.4% at the 10.0% sulfuric acid concentration, the FAME content of the high-FFA microalgal lipid was increased to 70.1% at a sulfuric acid concentration of only 0.1%. By combined sulfuric acid/SDBS treatment, high-FFA microalgal lipid was extracted in large yields; moreover, the amount of catalyst was remarkably reduced in the esterification of FFA.

Rapid separation of free fatty acids in vegetable oils by capillary zone electrophoresis.

INTRODUCTION: Olive oil is a very important product to human health since it inhibits formation of free radicals, tumour growth, lesions and inflammatory substances. High concentrations of free fatty acids in olive oils results in lipid deterioration due to oxidative or hydrolytic rancidity. OBJECTIVE: To optimise an alternative capillary zone electrophoresis methodology, under ultraviolet indirect detection and to determine free fatty acids in edible vegetable oils without derivatisation steps in sample preparation. METHODS: The condition used consisted of 15 mm NaH2 PO4 -Na2 HPO4 at pH ~6.86, 4.0 mm of sodium dodecybenzenesulphonate, 8.3 mm of Brij 35®, 45% v/v of acetonitrile and 2.1% of 1-octanol, injection at 12.0 mbar of pressure for 4 s, +19 kV of applied voltage and indirect detection at 224 nm, within an analysis time of 11 min. RESULTS: The capillary zone electrophoresis method was successfully applied to determination of free fatty acids in extra virgin olive oil, virgin olive oil and soybean oil samples. The comparison with the official volumetric titration method showed no significant difference within the 95% confidence interval. CONCLUSION: The main advantage to the proposed method is the possibility to observe the individual amount of the free fatty acids, which would be useful for researchers interested in studying the effect of the free fatty acids profile on oxidative process in food.

Inactivation of hepatitis C virus infectivity by human breast milk.

BACKGROUND: Hepatitis C virus (HCV) is spread through direct contact with blood, although alternative routes of transmission may contribute to the global burden. Perinatal infection occurs in up to 5% of HCV-infected mothers, and presence of HCV RNA in breast milk has been reported. We investigated the influence of breast milk on HCV infectiousness. METHODS/RESULTS: Human breast milk reduced HCV infectivity in a dose-dependent manner. This effect was species-specific because milk from various animals did not inhibit HCV infection. Treatment of HCV with human breast milk did not compromise integrity of viral RNA or capsids but destroyed the lipid envelope. Fractionation of breast milk revealed that the antiviral activity is present in the cream fraction containing the fat. Proteolytic digestion of milk proteins had no influence on its antiviral activity, whereas prolonged storage at 4°C increased antiviral activity. Notably, pretreatment with a lipase inhibitor ablated the antiviral activity and specific free fatty acids of breast milk were antiviral. CONCLUSIONS: The antiviral activity of breast milk is linked to endogenous lipase-dependent generation of free fatty acids, which destroy the viral lipid envelope. Therefore, nursing by HCV-positive mothers is unlikely to play a major role in vertical transmission.

Enrichment and quantification of monoacylglycerols and free fatty acids by solid phase extraction and liquid chromatography-mass spectrometry.

Quantification of monoacylglycerols (MAG) and free fatty acids (FA) is of interest in biological systems, in food, cosmetic and pharmaceutical products. This manuscript describes and validates a reversed phase liquid chromatography-tandem mass spectrometry based approach for simultaneous quantification of these analytes in fats and oils. Purification and concentration of MAG/FA were performed using cation exchange solid phase extraction, which allowed elimination of the abundant triacylglycerols. Following cleanup and concentration, the analytes were separated and detected with the aid of volatile ammonium-formate buffer. MAG were detected in positive ion mode, while FA were detected in negative ion mode. The method was validated by the method of standard additions and using stable isotope labeled internal standards. The results confirm the feasibility of quantifying these two classes of analytes simultaneously without any chemical derivatization. The obtained main quantitative features include: (1) lower limits of quantification 1-30ppm for MAG analytes, (2) lower limits of quantification 90-300ppm for FA analytes, (3) averaged inter-batch precision 6%, and (4) averaged bias -0.2% for MAG and 0.5% for FA. Various animal fat and vegetable oil samples were characterized for their MAG/FA profile indicating the usefulness of the method to address quality and authenticity of fats and oils.

Adipocyte-derived lipids modulate CD4+ T-cell function.

Adipose tissue contains several immune cells whose number and phenotype vary depending on the adiposity. In the present study, we show that IFN-γ(+) CD4(+) T cells are enriched in human adipose tissue compared with in blood. To gain insight into the underlying mechanisms, we investigated the possibility that human adipocytes modulate CD4(+) T-cell cytokine production and proliferation and show that CD4(+) T cells produced increased levels of IFN-γ when activated in the presence of adipocytes. This effect was mediated by soluble mediators, as shown in transwell and adipocyte-conditioned medium (ACM) transfer experiments. Additionally, ACM induced increased proliferation of CD4(+) T cells upon activation. Intriguingly, the proliferation-enhancing effect resided mainly in the lipid fraction of ACM, as shown upon separation of the protein and lipid fraction. Further separation of these lipids based on polarity revealed that the modulatory effect is confined to fractions containing free fatty acids. All identified fatty acids were able to individually enhance T-cell proliferation. These data indicate that adipocytes can modulate CD4(+) T-cell function through the release of lipids. Remarkably, free fatty acids were the most prominent modulators of T-cell proliferation, possibly leading to an accumulation of these cells in adipose tissue.