Biomedical subjects

Tao Li

Publications and source records attributed to Tao Li.

At least 37 records · Page 2Linked to original sources

PubMed2006

Reaction time of the Continuous Performance Test is an endophenotypic marker for schizophrenia: a study of first-episode neuroleptic-naive schizophrenia, their non-psychotic first-degree relatives and healthy population controls.

Sustained attention has been proposed as an endophenotype of schizophrenia, and consequently may be useful as a quantitative trait in genetic studies. In the present study, we used the continuous performance test (CPT) to measure sustained attention in 112 first-episode and neuroleptic-naive schizophrenic patients, 296 of their non-psychotic first-degree relatives, and 452 normal controls. Compared with controls, probands with schizophrenia showed worse performance on all measures of CPT. Parents, siblings and offspring of probands were also impaired on 'hit reaction time', an index of psychomotor processing speed of the correct response. Hit reaction time was also independent of the acute clinical features of the disease, indicating it is a trait rather than a state marker. Our findings supported the use of the hit reaction time measure of the CPT as an endophenotype marker for schizophrenia.

Adolescent↗

PubMed2006

Capillary electrophoresis with electrochemiluminescence detection for measurement of aspartate aminotransferase and alanine aminotransferase activities in biofluids.

A new sensitive assay for aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities in biofluids was developed, based on the separation and detection of alanine, glutamate, and aspartate using capillary electrophoresis (CE) with electrochemiluminescence (ECL) detection. The three amino acids were separated in 5 mM phosphate of pH 2.1 as background electrolyte, and detected on a 500 microm platinum disk electrode at 1.2V (versus Ag/AgCl) in the presence of 10 mM tris(2,2'-bipyridyl)ruthenium(II) dissolved in 80 mM phosphate of pH 10.5. A mass detection limit of 37.3 fmol (or 81.5 fmol) for glutamate, corresponding to the product in the enzyme reaction catalyzed by 1.24 x 10(-9)U AST (or 2.72 x 10(-9)U ALT) in a 30 min reaction period, was achieved. This assay was applied to investigate the cytotoxicity effect of ethanol on HepG2 cells and differentiating nonalcoholic steatohepatitis (NASH) from alcoholic liver disease, indicating that the technique is promising for the application in the cell biological and clinical fields.

Alanine↗

PubMed2006

Morphological characterization of suspended particles under wind-induced disturbance in Taihu Lake, China.

Sediments are disturbed by wind frequently, especially in the shallow lakes. The characteristics of resuspended sediment particles in Taihu Lake were studied under different wind velocities. It showed that sediment particles suspended obviously and particle number in overlying water increased directly under high wind-induced disturbance. Suspended solid (SS) concentration was less than 50 mg/l when the wind velocity was below 3.0 m/s, however, it increased to more than 300 mg/l when the wind velocity was 10.0 m/s. Two methods were used to measure the fractal characteristics of particles. One was light scattering and the other was image analysis. The three-dimensional fractal dimensions of suspended particles, measured by light scattering, were between 2.26 and 2.44; correspondingly, the two-dimensional fractal dimensions, calculated by image analysis, were between 1.44 and 1.77. Moreover, the three-dimensional fractal dimensions were directly proportional to two-dimensional fractal dimensions. The characteristic length of particles was calculated by image analysis. The minimum characteristic length was close to 8.5 microm when the wind velocity was 1.5 m/s at 50 cm beneath lake surface, while, the maximum characteristic length was approximate to 24 microm when the wind velocity was 10 m/s at the depth of 150 cm.

China↗

PubMed2006

Induction of IL-6 release from human T cells by PAR-1 and PAR-2 agonists.

Proteinase-activated receptors (PAR) have been recognized as playing an important role in inflammation and immune response. However, little is known of the expression and function of PAR on human T cells. In this study, the expression of PAR on highly purified human T cells was determined and the secretion of IL-6 from cultured T cells in response to serine proteinases and agonist peptides of PAR was examined. The results showed that T cells express PAR-1, PAR-2 and PAR-3 proteins and genes. Thrombin, trypsin and tryptase, but not elastase, were able to stimulate concentration-dependent secretion of IL-6 from T cells following a 16 h incubation period. The specific inhibitors of thrombin, trypsin and tryptase inhibited the actions of these proteinases on T cells, indicating that the enzymatic activity is essential for their actions. Agonist peptides of PAR SFLLR-NH2, TFLLRN-NH2 and SLIGKV-NH2, but not TFRGAP-NH2, GYPGQV-NH2 and AYPGKF-NH2, are also capable of inducing IL-6 release from T cells. In conclusion, induction of IL-6 secretion from T cells by thrombin, trypsin and tryptase is probably through the activation of PAR, suggesting that serine proteinases are involved in the regulation of immune response of the body.

Cell Separation↗

PubMed2006

Alphastatin downregulates vascular endothelial cells sphingosine kinase activity and suppresses tumor growth in nude mice bearing human gastric cancer xenografts.

AIM: To investigate whether alphastatin could inhibit human gastric cancer growth and furthermore whether sphingosine kinase (SPK) activity is involved in this process. METHODS: Using migration assay, MTT assay and Matrigel assay, the effect of alphastatin on vascular endothelial cells (ECs) was evaluated in vitro. SPK and endothelial differentiation gene (EDG)-1, -3, -5 mRNAs were detected by reverse transcription-polymerase chain reaction (RT-PCR). SPK activity assay was used to evaluate the effect of alphastatin on ECs. Matrigel plug assay in nude mice was used to investigate the effect of alphastatin on angiogenesis in vivo. Female nude mice were subcutaneously implanted with human gastric cancer cells (BGC823) for the tumor xenografts studies. Micro vessel density was analyzed in Factor VIII-stained tumor sections by the immunohistochemical SP method. RESULTS: In vitro, alphastatin inhibited the migration and tube formation of ECs, but had no effect on proliferation of ECs. RT-PCR analysis demonstrated that ECs expressed SPK and EDG-1, -3, -5 mRNAs. In vivo, alphastatin sufficiently suppressed neovascularization of the tumor in the nude mice. Daily administration of alphastatin produced significant tumor growth suppression. Immunohistochemical studies of tumor tissues revealed decreased micro vessel density in alphastatin-treated animals as compared with controls. CONCLUSION: Downregulating ECs SPK activity may be one of the mechanisms that alphastatin inhibits gastric cancer angiogenesis. Alphastatin might be a useful and relatively nontoxic adjuvant therapy in the treatment of gastric cancer.

Animals↗

PubMed2006

Purification, characterization and cytokine release function of a novel Arg-49 phospholipase A(2) from the venom of Protobothrops mucrosquamatus.

Group IIA phospholipase A(2) (PLA(2)) are major components in Viperidae/Crotalidae venom. In the present study, a novel PLA(2) named promutoxin with Arg at the site 49 has been purified from the venom of Protobothrops mucrosquamatus by chromatography. It consists of 122 amino acid residues with a molecular mass of 13,656 Da assessed by MALDI-TOF. It has the structural features of snake venom group IIA PLA(2)s, but has no PLA(2) enzymatic activity. Promutoxin shows higher amino acid sequence identity to the K49 PLA(2)s (72-95%) than to D49 PLA(2)s (52-58%). Promutoxin exhibits potent myotoxicity in the animal model with as little as 1 microg of promutoxin causing myonecrosis and myoedema in the gastrocnemius muscle of mice. Promutoxin is also able to stimulate the release of IL-12, TNFalpha, IL-6 and IL-1beta from human monocytes, and induce IL-2, TNFalpha and IL-6 release from T cells, indicating that this snake venom group IIA PLA(2) is actively involved in the inflammatory process in man caused by snake venom poisoning.

Amino Acid Sequence↗

PubMed2006

Determination of the refractive index and size distribution of aerosol from dual-scattering-angle optical particle counter measurements.

A method is presented for inferring both the refractive index and the size distribution of aerosol from observations of a dual-scattering-angle optical particle counter (OPC). An existing prototype of an OPC with 60 degree and 90 degree dual-scattering angles was used for the experiments. Based on the high sensitivity of the OPC response to the refractive index of particulates, two families of size distribution curves may be calculated. The solution of the refractive index corresponds to the superposition of the two size distributions. This method was applied to the simulation and to the field measurements conducted in Beijing and Hefei, and the results of both are presented.

Journal Article↗

PubMed2006

Conditional ablation of MHC-II suggests an indirect role for MHC-II in regulatory CD4 T cell maintenance.

Although the importance of MHC class II (MHC-II) in acute homeostatic proliferation of regulatory T (Treg) cells has been established, we considered here the maintenance and state of Treg cells in mice that are almost completely devoid of MHC-II in their periphery but still make their own CD4 T cells and Treg cells. The latter was accomplished by conditional deletion of a loxP-flanked MHC-II beta-chain allele using a TIE2Cre transgene, which causes a very high degree of deletion in hemopoietic/endothelial progenitor cells but without deletion among thymic epithelial cells. Such conditional MHC-II-deficient mice possess their own relatively stable levels of CD4+CD25+ cells, with a normal fraction of Foxp3+ Treg cells therein, but at a level approximately 2-fold lower than in control mice. Thus, both Foxp3low/- CD4+CD25+ cells, said to be a major source of IL-2, and IL-2-dependent Foxp3+ Treg cells are reduced in number. Furthermore, CD25 expression is marginally reduced among Foxp3+ Treg cells in conditional MHC-II-deficient mice, indicative of a lack of MHC-II-dependent TCR stimulation and/or IL-2 availability, and IL-2 administration in vivo caused greatly increased cell division among adoptively transferred Treg cells. This is not to say that IL-2 can cause Treg cell division in the complete absence of MHC-II as small numbers of MHC-II-bearing cells do remain in conditional MHC-II-deficient mice. Rather, this suggests only that IL-2 was limiting. Thus, our findings lend support to the proposal that Treg cell homeostasis depends on a delicate balance with a population of self-reactive IL-2-producing CD4+CD25+ cells which are themselves at least in part MHC-II-dependent.

Animals↗

PubMed2006

Splenic vasculopathy in portal hypertension patients.

AIM: To investigate the interaction between portal hypertension, splanchnic hyperdynamic circulation and splanchnic vasculopathy by observing splenic arterial and venous pathological changes and the ro1e of extra-cellular matrix in the pathogenesis of portal hypertensive vasculopathy by measuring the expression of type I and type III procollagen mRNA in splenic venous walls of portal hypertensive patients. METHODS: Morphological changes of splenic arteries and veins taken from portal hypertensive patients (n=20) and normal controls (n=10) were observed under optical and electron microscope. Total RNA was extracted and the expression of type I and type III procollagen mRNA in splenic venous walls of portal hypertensive patients (n=20) was semi-quantitatively detected using reverse transcription-polymerase chain reaction (RT-PCR). RESULTS: Under optical microscope, splenic arterial intima was destroyed and internal elastic membrane and medial elastic fibers of the splenic arterial walls were degenerated and broken. Splenic venous intima became remarkably thick. Endothelia1 cells were not intact with formation of mural thrombus. The tunica media became thickened significantly due to hypertrophy of smooth muscles. Fibers and connective tissues were increased obviously. Under electron microscope, smooth muscle cells of the splenic arteries were degenerated and necrotized. Phenotypes of smooth muscle cells changed from constrictive into synthetic type. Red blood cells and platelets accumulated around the damaged endothelial cells. Synthetic smooth muscle cells were predominant in splenic veins and their cytoplasma had plentiful rough endoplasmic reticulum ribosomes and Golgi bodies. Along the vascular wall, a lot of collagen fibers were deposited, the intima was damaged and blood components accumulated. There was no significant difference in the expression of type I procollagen mRNA in splenic venous wall between the patients with portal hypertension and those without portal hypertension (P>0.05), but the expression of type III procoagen mRNA was significantly stronger in the patients with portal hypertension than in those without portal hypertension (P<0.01). CONCLUSION: Type III procollagen and collagen might be important extra-cellular matrix resulting in neointimal formation and vascular remodeling in the pathogenesis of portal hypertensive vasculopathy. The pathological changes in splenic arteries and veins exist in portal hypertension patients. There might be an interaction between portal hypertension, splanchnic hyperdynamic circulation and splanchnic vasculopathy.

Adult↗

PubMed2006

Characterization of the phosphate adsorption and morphology of sediment particles under simulative disturbing conditions.

The behavior of nutrient release and adsorption from sediments was influenced by hydrodynamic disturbance significantly. The resuspension/sedimentation processes of sediment particles and phosphate adsorption in Taihu Lake were investigated under different disturbing intensity by utilizing simulative conditions. The effect of morphological characteristics of suspended particles on phosphate adsorption was also studied. In order to elucidate the characteristics of particles suspended by disturbance, the size and structure of particles during different time were monitored on-line by using photometric dispersion and particles image analysis. The method of fractal geometry to explore the morphology characteristics of particles was also used. The results showed that sediments suspended obviously and the phosphate concentration of overlying water decreased rapidly when strong disturbance was applied. Moreover, two different disturbing conditions, one was static condition without wind and the other was weak disturbing intensity with slow wind velocity, following heavy disturbance were compared, and it turned out that the turbidity and phosphate concentration were lower in the latter because the size and the structure of suspended particles were more favorable in the latter disturbing condition. The flocculation index of suspended particles was 0.25 and characteristic length was 30 microm under 100 rpm disturbance; comparatively, when heavy disturbance increased to 120 rpm, the flocculation index grew up to 0.60 and the characteristic length was greater than 60 microm. The fractal dimensions of suspended particles were between 1.65 and 1.92.

Adsorption↗

PubMed2006

Characterization of prolidase activity using capillary electrophoresis with tris(2,2'-bipyridyl)ruthenium(II) electrochemiluminescence detection and application to evaluate collagen degradation in diabetes mellitus.

A new method for prolidase (PLD, EC 3.4.13.9) activity assay was developed based on the determination of proline produced from enzymatic reaction through capillary electrophoresis (CE) with tris(2,2'-bipyridyl)ruthenium(II) [Ru(bpy)3(2+)] electrochemiluminescence detection (ECL). A detection limit of 12.2 fmol (S/N = 3) for proline, corresponding to 1.22 x 10(-8) units of prolidase catalyzing for 1 min was achieved. PLD activity determined by CE-ECL method was in agreement with that obtained from the classical Chinard's one. CE-ECL showed its powerful resolving ability and selectivity as no sample pretreatment was needed and no interference existed. The clinical utility of this method was successfully demonstrated by its application to assay PLD activity in the serum of diabetic patients in order to evaluate collagen degradation in diabetes mellitus (DM). The results indicated that enhanced collagen degradation occurred in DM.

2,2'-Dipyridyl↗

PubMed2006

Evaluation of a susceptibility gene for schizophrenia: genotype based meta-analysis of RGS4 polymorphisms from thirteen independent samples.

BACKGROUND: Associations between schizophrenia (SCZ) and polymorphisms at the regulator of G-protein signaling 4 (RGS4) gene have been reported (single nucleotide polymorphisms [SNPs] 1, 4, 7, and 18). Yet, similar to other SCZ candidate genes, studies have been inconsistent with respect to the associated alleles. METHODS: In an effort to resolve the role for RGS4 in SCZ susceptibility, we undertook a genotype-based meta-analysis using both published and unpublished family-based and case-control samples (total n = 13,807). RESULTS: The family-based dataset consisted of 10 samples (2160 families). Significant associations with individual SNPs/haplotypes were not observed. In contrast, global analysis revealed significant transmission distortion (p = .0009). Specifically, analyses suggested overtransmission of two common haplotypes that account for the vast majority of all haplotypes. Separate analyses of 3486 cases and 3755 control samples (eight samples) detected a significant association with SNP 4 (p = .01). Individual haplotype analyses were not significant, but evaluation of test statistics from individual samples suggested significant associations. CONCLUSIONS: Our collaborative meta-analysis represents one of the largest SCZ association studies to date. No individual risk factor arose from our analyses, but interpretation of these results is not straightforward. Our analyses suggest risk due to at least two common haplotypes in the presence of heterogeneity. Similar analysis for other putative susceptibility genes is warranted.

Case-Control Studies↗

PubMed2006

The development and regulation of occupational exposure limits in China.

Of the 700 million workers in China, approximately 200 million workers are potentially exposed to industrial hazards. Although the promulgation and implementation of occupational exposure limits (OELs) in China began in the mid-1950, a systematic approach was not formalized until the formation of the Subcommittee of Occupational Health Standards Setting (SOHSS) in 1981. More recently, the 2002 Occupational Disease Prevention and Control Act of the People's Republic of China created the legislative framework for the development and enforcement of OELs. The SOHSS, whose members are primarily health professionals, is the organization responsible for the development of recommended standards, under the auspices of the Ministry of Health. The philosophy of OEL development of the SOHSS consists of a two-step approach: (1) an initial health-based recommended standard is established based on scientific data, and (2) a final law-based standard takes into consideration both socioeconomic and technological feasibility. Governmental agencies such as the Centers for Diseases Control and Prevention and the Institutes of Public Health Supervision at the state, provincial or municipal levels are charged with the responsibilities of the enforcement of OELs. The process and challenges in the enforcement of OELs are discussed. A comparison is made between selected Chinese OELs and those in other countries. The OELs for benzene and industrial dusts (including silica) are discussed in some detail.

Carcinogens, Environmental↗

PubMed2006

[Inhibition of alphastatin on angiogenesis in human endothelial cells and the mechanism thereof: an experimental study].

OBJECTIVE: To explore the effect of alphastatin on angiogenesis activity of human umbilical vein endothelial cells and mechanism thereof. METHOD: Human umbilical vein endothelial cells of the line ECV304 was cultured. Hepatic growth factor (HGF) and alphastatin of the concentrations of 10, 100, or 1000 nmol/L were use in migration test ECV304 cells at logarithmic stage were inoculated in a 96-well plate. Alphastatin of different concentrations was added, 24, 48, 72, and 96 hours later MTT was added to detect the A(490) nm values with and draw a growth curve. Phorbol 12-myristate 13-acetate (PMA) was used as positive group. The formation of capillary-like structure was examined with fluorescent microscopy. RT-PCR was used to examine the expression of sphingosine kinase (SPK) mRNA in the ECV304 cells. ECV304 cells were treated with alphastatin of 10 nmol/L, 100 nmol/L, or 1000 nmol/L respectively. SPK activity was examined by using [gamma-(32)P] ATP. RESULTS: The number of migrated cells treated with alphastatin of the concentrations of 10, 100, and 1000 nmol/L were (103 +/- 4), (75 +/- 3), and (13 +/- 1) respectively, all significantly lower than that of the HGF group (131 +/- 4, all P < 0.05). The values at different time points of the ECV304 cells treated with alphastatin of different concentrations were not significantly different from that of the HGF group. The area of capillary-like structure of the PMA group was 2996 +/- 31 microm(2)/field, and those of the groups of alphastatin of the concentrations of 100 and 1000 nmol/L were 1509 +/- 30 microm(2)/field and 1301 +/- 20 microm(2)/field respectively, all significantly less than that of the PMA group (2996 +/- 31 microm(2)/field, all P < 0.05). However, there was not a dose-dependent manner in the inhibitive activity of alphastatin on the formation of capillary-like structure. RT-PCR showed that quantity of SPK mRNA product was amplified from the ECV304 cells. The S1P activity of the ECV304 treated with alphastatin was significantly lower than that of the control group, especially when the concentration of alphastatin was 100 nmol/L and 12 hours after treatment. CONCLUSION: Alphastatin shows a potent antiangiogenic property, which may be closely associated with the downregulation of endothelial cells SPK activity.

Cell Line↗

PubMed2006

CTCF mediates interchromosomal colocalization between Igf2/H19 and Wsb1/Nf1.

Gene transcription may be regulated by remote enhancer or insulator regions through chromosome looping. Using a modification of chromosome conformation capture (3C) and fluorescence in situ hybridization, we found that one allele of the insulin-like growth factor 2 (Igf2)/H19 imprinting control region (ICR) on chromosome 7 colocalized with one allele of Wsb1/Nf1 on chromosome 11. Omission of CCCTC-binding factor (CTCF) or deletion of the maternal ICR abrogated this association and altered Wsb1/Nf1 gene expression. These findings demonstrate that CTCF mediates an interchromosomal association, perhaps by directing distant DNA segments to a common transcription factory, and the data provide a model for long-range allele-specific associations between gene regions on different chromosomes that suggest a framework for DNA recombination and RNA trans-splicing.

Alleles↗

PubMed2006

In vivo research in astrocytoma cell proliferation with 1H-magnetic resonance spectroscopy: correlation with histopathology and immunohistochemistry.

INTRODUCTION: Assessment of brain tumor proliferative potential provides important prognostic information that supplements standard histopathologic grading. Proton magnetic resonance spectroscopy ((1)H-MRS) gives completely different information, relating to cell membrane proliferation, neuronal damage, energy metabolism and necrotic transformation of brain or tumor tissues. The aim of this study was to investigate the relationship between (1)H-MRS and tumor proliferative potential in astrocytomas. METHODS: We studied 34 patients with histologically verified astrocytomas using the (1)H-MRS protocol following routine MRI preoperatively. The tumor in 26 of these patients was classified as grade I/II (low grade), and the tumor in the remaining patients as grade III/IV (high grade) according to the World Health Organization classification criteria of nervous system tumors (2000). The tumor in 21 patients was homogeneous astrocytoma, and of these 17 were classified as low grade and 4 as high grade. Expression of proliferating cell nuclear antigen (PCNA) was determined immunohistochemically using streptavidin-biotin-peroxidase complex (SP) staining. RESULTS: The ratios of choline (Cho) to N-acetylaspartate (NAA) and Cho to creatine (Cr) in those with high-grade astrocytomas (n=4) were significantly higher than in those with low-grade astrocytomas (n=17) (t=2.899, P=0.009; t=3.96, P=0.001, respectively), and were found to be significantly correlated with the expression of PCNA in 21 patients with homogeneous astrocytomas (r=0.455, P=0.038; r=0.633, P=0.002, respectively). CONCLUSIONS: We conclude that (1)H-MRS may be a valuable method for predicting preoperatively the degree of malignancy of homogeneous astrocytomas by enabling the calculation of the Cho/NAA and Cho/Cr ratios in vivo, and indirect evaluation of the tumor proliferative potential and prognosis, which are not available using conventional magnetic resonance imaging (MRI).

Adolescent↗

PubMed2006

Sensing of Lys 63-linked polyubiquitination by NEMO is a key event in NF-kappaB activation [corrected].

The transcription factor NF-kappaB is sequestered in the cytoplasm in a complex with IkappaB. Almost all NF-kappaB activation pathways converge on IkappaB kinase (IKK), which phosphorylates IkappaB resulting in Lys 48-linked polyubiquitination of IkappaB and its degradation. This allows migration of NF-kappaB to the nucleus where it regulates gene expression. IKK has two catalytic subunits, IKKalpha and IKKbeta, and a regulatory subunit, IKKgamma or NEMO. NEMO is essential for NF-kappaB activation, and NEMO dysfunction in humans is the cause of incontinentia pigmenti and hypohidrotic ectodermal dysplasia and immunodeficiency (HED-ID). The recruitment of IKK to occupied cytokine receptors, and its subsequent activation, are dependent on the attachment of Lys 63-linked polyubiquitin chains to signalling intermediates such as receptor-interacting protein (RIP). Here, we show that NEMO binds to Lys 63- but not Lys 48-linked polyubiquitin, and that single point mutations in NEMO that prevent binding to Lys 63-linked polyubiquitin also abrogates the binding of NEMO to RIP in tumour necrosis factor (TNF)-alpha-stimulated cells, the recruitment of IKK to TNF receptor (TNF-R) 1, and the activation of IKK and NF-kappaB. RIP is also destabilized in the absence of NEMO binding and undergoes proteasomal degradation in TNF-alpha-treated cells. These results provide a mechanism for NEMO's critical role in IKK activation, and a key to understanding the link between cytokine-receptor proximal signalling and IKK and NF-kappaB activation.

Biosensing Techniques↗

PubMed2006

Role of MHC class II on memory B cells in post-germinal center B cell homeostasis and memory response.

We investigated the role of B cell Ag presentation in homeostasis of the memory B cell compartment in a mouse model where a conditional allele for the beta-chain of MHC class II (MHC-II) is deleted in the vast majority of all B cells by cd19 promoter-mediated expression of Cre recombinase (IA-B mice). Upon T cell-dependent immunization, a small number of MHC-II(+) B cells in IA-B mice dramatically expanded and restored normal albeit delayed levels of germinal center (GC) B cells with an affinity-enhancing somatic mutation to Ag. IA-B mice also established normal levels of MHC-II(+) memory B cells, which, however, subsequently lost MHC-II expression by ongoing deletion of the conditional iab allele without significant loss in their number. Furthermore, in vivo Ag restimulation of MHC-II(-) memory B cells of IA-B mice failed to cause differentiation into plasma cells (PCs), even in the presence of Ag-specific CD4(+) T cells. In addition, both numbers and Ag-specific affinity of long-lived PCs during the late post-GC phase, as well as post-GC serum affinity maturation, were significantly reduced in IA-B mice. These results support a notion that MHC-II-dependent T cell help during post-GC phase is not absolutely required for the maintenance of memory B cell frequency but is important for their differentiation into PCs and for the establishment of the long-lived PC compartment.

Animals↗