stayBiologyChina Israel MonopolycombinationThe molecules of areLigands(Ligand) Biologyhigh polymerThe ability to form intermediate complexes between ligands is called affinity（Affinity[4])。Also refers to a completeantibodyMolecularantigenThe binding strength, affinity andaffinityThe binding value of antibody is related to the number of effective epitopes of antigen.
According to the change of affinity during antibody production, IgGantibodyAffinity index (AI), which can be used for identificationpathogenPrimary (recent) infection and previous infection.IgG antibodyIn the early stage of infection, AI is relatively low, and gradually increases with time.Therefore, some studies suggest that AI<30% is low affinityantibody, promptPrimary infection；AI>50% is a high affinity antibody, indicating previous or recurrent infection;AI between 30% and 50% is a medium affinity antibody.
Determination of Antibody Affinity to Differentiate Primary Infection from Reactive Infection
Announce
edit
Research background
Antibody AI has been widely used to identify othersCytomegalovirus(human cytomegalovirus，HC-MV)、EBV、tox andmycoplasma pneumoniae The primary infection and reinfection or reactivation of infection.The detection of anti HCMV IgG AI in a single sample has high sensitivity and specificity in judging the recent primary infection of HCMV.On the basis of ELISA, warm cultivation method[1]Determine anti HCMV IgG AI, study the influence of antibody concentration on AI determination, and judge the primary infection and reactivation infection of HCMV through AI.
Discussion of results
When the concentration of anti HCMV IgG is too high, the coating antigen is relatively insufficient, and there is excess IgG. At this time, due to the high affinity of IgGureaUnder the action ofantigenThe combination of non denatured pore IgG and coating antigen has been saturated, and the measured A value is relatively constant, so the AI measurement is affected and a higher AI value is obtained.This is consistent with the report of Kli mashevskaya et al.However, Dangel et al. believed that high concentration of IgG would cause false low AI value results, which may be related to different experimental methods and reagents.When detecting AI with plasma anti HC-MV IgG concentration of about 100 IU/mL, the AI value fluctuates with different dilution times, but does not affect the judgment of the results.
The duration of urea treatment can affect the level of AI, especially the low AI sample will be significantly higher than the true AI value due to insufficient denaturation time.In domestic research, the simplified elution method is often used in the detection of anti HCMV IgG AI, and 50% is considered as the short-term judgmentPrimary infectionThe boundary value of.After comparing the results of 8 plasma samples detected by the two methods, the AI detected by the warm incubation method was lower than that by the elution method, but there was no significant difference, indicating that the warm incubation method (final concentration of denatured pore urea 4mol/L) and the elution method had similar ability to denature low affinity antibodies.Therefore, this study adopts Hedman's interpretation of AI, judging the recent primary infection with AI<30%, excluding the recent primary infection with AI>30%, and judging it as past infection or recurrent infection.
Anti HCMV-MP-IgM Not only in the recent primary infection of HCMV, but also secondary infection can occur.Specific IgM is used to judge the active infection of HCMV, and the combination of anti HCMV IgM and AI can effectively judge the time of infection.In 50 copiesplasmaAmong them, there were 15 cases with AI<30%, which were judged as recent primary infection. Among them, 5 cases had anti HCMV IgM, and the other 10 cases could not be detected because anti HCMV IgM turned negative;There were 16 cases with AI>50%, and the infection time was judged to be more than 3 months. Among them, 5 cases with positive anti HCMV IgM were judged as recurrent infection.
Lutz et al. observed that the maturation of antibodies in immunosuppressed patients with primary infection of HCMV was significantly delayed, and it took more than one year for IgG to change from low affinity to high affinity, while the normal people took two to six months.In this study, we observed the changes of plasma anti HCMV IgG AI in 8 immunosuppressed patients, of which 6 cases had no significant increase in AI.Therefore, this feature should be taken into account when using AI to judge the infection time in such patients, and the AI changes in immunosuppressed patients need in-depth research.
The determination of anti HCMV IgG AI by warm cultivation method can distinguish the primary infection and reactivation infection of HCMV, and the situation and time of infection can be judged by combining anti HCMV IgM.This is of great significance for the diagnosis of HCMV infection in pregnant women.Using AI to determine the type of HCMV infection in pregnant women can determine whether to proceed furtherAmniocentesisThe intrauterine HCMV infection was diagnosed by other invasive tests.Presence of immunosuppressed patientsantibodyThe production and maturation of HCMV are delayed, and the detection of HCMV nucleic acid can be used asSerological diagnosisSupplement to.[2]
Expression of low affinity receptor of nerve growth factor in hepatocytes
Announce
edit
nerve growth factorrecipient(NGFR) consists of twoSubunitThey are composed of low affinity nerve growth factor receptor P75 (P75) and high affinity nerve growth factor receptor Tyrosine kinase A (TrkA).There is no such report in China.Related studies used activated HSCs andhepatic fibrosis Observe the expression and distribution of P75 in HSCs of patients and rats to explore the pathogenesis of liver fibrosisnerve growth factor(nerve hepatic stellate cells, growth factor, NGF) for the clinical treatment of liver fibrosis to lay an experimental foundation.
In 1951, Levi Montalcini first found NGF in mouse sarcoma cells, which plays an important role in the development, differentiation and maintenance of the special functions of neurons of the nervous system. Later studies found that NGF is widely distributed in body tissues and organs, and many cell lines, including HSCs, exist.Research shows that NGFR plays a role through P75 and TrkA.TrkA is the functionality of NGFrecipient, transmit signals, promotenerve cellRegeneration, while the function of P75 is still unclear.In 1996, foreign scholars reported that P75 could independently induce apoptosis without the participation of TrkA.Therefore, studying the expression and distribution of P75 in HSCs is helpful to explore the function and mechanism of P75.
HSCs are synthesized extracellular during the formation of liver fibrosisstromaThe most important cell of,hepatic fibrosis In the recovery phase, apoptotic HSCs increased significantly.Experiments prove that in CClfourApoptosis of HSCs is the central event in the process of automatic recovery after hepatic fibrosis in rats.Therefore, inhibiting HSCs proliferationinduceApoptosis is an important strategy for anti liver fibrosis.Takahashi and others reported that NGFR iscell membraneReceptors, which exist in a variety ofcell surface。Trim et al. reported that static cultured rat HSCs did not express P75, while activated HSCs expressed P75;In human and rat liver, HSCs express P75
The cells did not express P75, and P75 responded to the stimulation of NGF and entered into apoptosis;After co culturing 100 μ g/L NGF with HSCs for 24h, the number of apoptosis in HSCs increased significantly in a dose-dependent manner. It was pointed out that NGF could induce apoptosis in HSCs cultured in vitro, and its mechanism might include the effects of NGF and P75.
It was observed that the expression of P75 in HSCs of patients with liver fibrosis and rats was consistent with that of Trim;P75 was expressed on the HSCs membrane in linear or granular distribution, which was consistent with Takahashi's results;At the same time, the experiment found that P75 was also expressed in hepatocytes of patients with liver fibrosis and rats, which is inconsistent with the specific expression of P75 in HSCs reported by Trim, and needs further discussion.
Rabizadeh et al. believed that the mechanism of P75 inducing apoptosis of HSCs was that NGFCell surface receptorP75 binding induces neuronal apoptosis.Therefore, it is speculated that the mechanism of action may be that NGF and P75 bind on the HSCs membrane, which can promote the activity of P75 induced HSCs, promote the apoptosis of HSCs, and is not conducive to the progress of liver fibrosis.
The discovery of P75 in HSCs provides a new target for the development of anti hepatic fibrosis drugs.It is speculated that when liver fibrosis occurs, high concentration of NGF may obtain better curative effect;At the same time, if we can find a drug that can up regulate the expression of P75 in activated HSCs, it will play a positive role in inhibiting the process of liver fibrosis.[3]
