A high sensitivity myeloperoxidase latex turbidimetric assay kit and method

Abstract

This invention discloses a highly sensitive latex turbidimetric assay kit and method for myeloperoxidase (MPA). The kit includes reagent R1 and reagent R2. Reagent R2 comprises latex microspheres conjugated with myeloperoxidase antibody. Reagent R1 contains a first reducing agent and a second reducing agent, wherein the first reducing agent is a moderately organic reducing agent and the second reducing agent is a moderately inorganic reducing agent. By adding the first and second reducing agents to reagent R1, this invention effectively ensures small accuracy deviation, good precision, and high sensitivity of the reagent. Furthermore, the thermal stability and long-term stability of the reagent are significantly improved. Therefore, the kit of this invention better meets clinical needs and has promising application prospects.

Description

Technical Field

[0001] This invention belongs to the field of immunoassay technology, specifically relating to a highly sensitive myeloperoxidase latex turbidimetric assay kit and assay method. Background Technology

[0002] Myeloperoxidase (MPO), also known as peroxidase, is a heme protease associated with the heme cofactor and a member of the heme peroxidase superfamily. With in-depth research on MPO, it has been discovered that MPO gene polymorphisms lead to individual differences in susceptibility to certain diseases and are closely related to the occurrence and development of many human diseases, thus attracting increasing attention from scholars both domestically and internationally. Coronary heart disease (CHD) is the most common disease of the cardiovascular system, and atherosclerosis (AS) is a crucial pathological basis for its development. During the pathogenesis of AS, oxidized low-density lipoprotein (LDL) typically occurs, leading to macrophages engulfing lipids and transforming into foam cells. Foam cell formation plays a key role in the development of AS. Studies have found that MPO promotes the formation of AS lesions. By generating free radicals and various reactive substances, MPO promotes plaque formation and increases instability, accelerating AS progression and leading to various complications such as acute coronary syndrome (ACS). Research has shown that individuals with MPO deficiency have a significantly reduced risk of cardiovascular disease. Elevated MPO levels are not only associated with susceptibility to coronary artery disease but can also predict the risk of early myocardial infarction.

[0003] Myeloperoxidase (MPO) is abundant in neutrophils. It is synthesized in the bone marrow and stored in azurophilic granules before granulocytes enter circulation. External stimuli can cause neutrophil aggregation, thereby releasing myeloperoxidase. MPO has a relative molecular weight of 150 kDa and is a tetramer formed by two subunits linked by disulfide bonds. Each subunit consists of a heavy chain α (relative molecular weight 60 kDa) and a light chain β (relative molecular weight 15 kDa).

[0004] Adding an appropriate amount of reducing agent to the reagent can break the disulfide bonds in the myeloperoxidase tetramer, forming monomers. This can significantly improve the reagent's sensitivity when the myeloperoxidase content is low. Currently, reducing agents such as mercaptoethanol and DTT are commonly used to break the disulfide bonds in protein tetramers. However, these strong reducing agents also have significant drawbacks. On the one hand, they are easily oxidized and unstable; on the other hand, excessive breaking of protein disulfide bonds can reduce the linearity of the reagent when the protein content is high. Summary of the Invention

[0005] In view of this, the present invention aims to provide a myeloperoxidase latex turbidimetric assay kit, which improves the reducing agent in the kit so that the kit has both high sensitivity and good stability, without affecting the linearity of the reagent.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows:

[0007] A highly sensitive myeloperoxidase latex turbidimetric assay kit, the kit comprising reagent R1 and reagent R2, reagent R1 containing a first reducing agent and a second reducing agent, and reagent R2 comprising latex microspheres conjugated with myeloperoxidase antibody; wherein the first reducing agent is a moderately organic reducing agent and the second reducing agent is a moderately inorganic reducing agent.

[0008] Preferably, in the above-mentioned kit, the moderate organic reducing agent is one of mercaptoacetic acid, mercaptopropionic acid, mercaptoacetate, and mercaptopropionate, and the moderate inorganic reducing agent is one of sulfite, nitrite, phosphite, and hypophosphite. The term "moderate" in the context of the moderate organic and moderate inorganic reducing agents of this invention refers to a moderate reducing power, falling between strong and low reducing power.

[0009] More preferably, in the above kit, the mercaptoacetate is sodium mercaptoacetate or potassium mercaptoacetate, the mercaptopropionate is sodium mercaptopropionate or potassium mercaptopropionate, the sulfite is one of sodium sulfite, potassium sulfite, ammonium sulfite, sodium bisulfite, potassium bisulfite, and ammonium bisulfite, the nitrite is sodium nitrite or potassium nitrite, the phosphite is one of sodium phosphite, potassium phosphite, calcium phosphite, and zinc phosphite, and the hypophosphite is one of sodium hypophosphite, potassium hypophosphite, magnesium hypophosphite, and calcium hypophosphite.

[0010] Preferably, in the above kit, the composition of reagent R1 is as follows: 100-200 mmol / L buffer, 0.1-1.0 g / L EDTA-2Na, 0.1-5 wt% sodium chloride, 0.1-1.0 wt% Triton X-100, 0.5-1.5 wt% first reducing agent and 0.5-2.0 wt% second reducing agent, and the pH of reagent R1 is 6.5-7.5.

[0011] More preferably, in the above kit, the buffer in reagent R1 is one of Good's buffer, Tris buffer, and phosphate buffer.

[0012] Preferably, in the above kit, reagent R2 consists of a preservation solution and latex microspheres conjugated with myeloperoxidase antibody. The preservation solution specifically comprises: 20-50 mmol / L Good's buffer, 0.5-1.5 wt% sodium chloride, 0.05-0.15 wt% sodium azide, 0.05-0.5 wt% Tween-20 and 0.5-5 wt% trehalose, with a pH of 7.0-7.5.

[0013] Preferably, in the above kit, the latex microspheres conjugated with myeloperoxidase antibody in reagent R2 are prepared as follows: latex microspheres are added to activation buffer, and then EDC is added for activation; myeloperoxidase antibody is diluted with conjugation buffer and then conjugated with the activated latex microspheres; after conjugation, blocking solution is added; after blocking, the supernatant is removed by centrifugation to obtain the product.

[0014] More preferably, the preparation of the R2 reagent includes the following steps:

[0015] (1) Take 5 mL of latex microspheres with a particle size of 150-250 nm (solid content of 10%), add 15-30 mL of activation buffer (10-50 mmol / L LMES buffer, pH value of 5.0-6.0) and mix well;

[0016] (2) Add 1.5-2 mL of 5 mg / ml activator (5 mg / ml EDC, freshly prepared) to step (1), mix well, and place in a constant temperature shaker to react for 20-30 min at a temperature range of 30-37℃.

[0017] (3) Dilute the antibody to 0.5 mg / mL with coupling buffer (10-50 mmol / L HEPES buffer, pH 7.0-8.0), add 20-30 mL of the 0.5 mg / mL diluted antibody to step (2), mix well, and place in a constant temperature shaker for 2-3 h at a temperature range of 30-37℃.

[0018] (4) Add 2.5-5 mL of blocking solution (10-20 wt% BSA) to step (3), mix well, and place in a constant temperature shaker to react for 0.5-1 h at a temperature range of 30-37℃.

[0019] (5) After sealing, centrifuge the above solution in a refrigerated high-speed centrifuge with centrifugation parameters of 15,000 rpm and centrifugation time of 30-50 minutes. After centrifugation, remove the supernatant, add 250-300 mL of preservation solution to reconstitute, and mix evenly by sonication.

[0020] Based on the myeloperoxidase latex turbidimetric assay kit provided by this invention, this invention further provides a method for detecting myeloperoxidase latex turbidimetric assay, specifically: using the kit of this invention to directly determine the content of MPO in a sample through an antigen-antibody reaction. The principle is as follows: MPO in the sample encounters MPO antibody-sensitized latex microspheres in reagent R2 in solution, undergoing an agglutination reaction and producing a certain degree of turbidity; in the presence of a certain amount of antibody, the level of this turbidity is directly proportional to the content of the antigen (i.e., MPO); at a specific wavelength, by comparing with a similarly treated calibration solution, the content of MPO in the sample is quantitatively detected.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] The first reducing agent added to reagent R1 in this invention has a lower reducing power than strong reducing agents such as mercaptoethanol and DTT, but it can still break the disulfide bonds in the myeloperoxidase tetramer to form monomers. On the one hand, when the myeloperoxidase content is low, the first reducing agent breaks the disulfide bonds in the myeloperoxidase tetramer to form monomers, while simultaneously reducing the steric hindrance for the binding of myeloperoxidase to the antibody coupled on the latex microspheres, which can greatly improve the sensitivity of the reagent. On the other hand, an appropriate amount of moderately organic reducing agent has a more significant effect when the myeloperoxidase content is low, but its effect is not significant when the myeloperoxidase content is high, thus not affecting the linearity of the reagent. Furthermore, to improve the stability of the first reducing agent, an appropriate amount of a second reducing agent, an inorganic salt reducing agent, is also added to reagent R1 in this invention. This second reducing agent further stabilizes the first reducing agent, thereby allowing the high sensitivity performance of the reagent to be maintained for a longer period. Detailed Implementation

[0023] The technical solution of the present invention will be clearly and completely described below with reference to embodiments. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0024] Unless otherwise specified, the methods described in the following examples are conventional; the reagents and materials described are commercially available unless otherwise specified.

[0025] Example 1

[0026] The kit in this example includes reagent R1 and reagent R2, wherein the components of reagent R1 are:

[0027] Good's buffer: 100 mmol / L;

[0028] EDTA-2Na: 1.0 g / L;

[0029] Sodium chloride: 2 wt%;

[0030] Triton X-100: 0.5 wt%;

[0031] Thioglycolic acid (first reducing agent): 0.5 wt%;

[0032] Sodium sulfite (second reducing agent): 0.5 wt%;

[0033] Sodium azide: 0.1 wt%;

[0034] The pH value is 7.5.

[0035] The R2 reagent consists of a preservation solution and latex microspheres conjugated with myeloperoxidase antibody, and the components of the preservation solution are:

[0036] Good's buffer: 25 mmol / L;

[0037] Sodium chloride: 0.9 wt%;

[0038] Sodium azide: 0.1 wt%;

[0039] Tween-20: 0.1 wt%;

[0040] Trehalose: 2.5 wt%;

[0041] The pH value is 7.2.

[0042] The preparation process of reagent R2 is as follows:

[0043] (1) Take 5 mL of latex microspheres, add 20 mL of MES buffer and mix well;

[0044] (2) Add 2 mL of 5 mg / ml activator (5 mg / ml EDC, freshly prepared) to step (1), mix well, and place in a constant temperature shaker for 30 min. Temperature range: 30℃.

[0045] (3) Dilute the myeloperoxidase antibody (in this example, a rabbit polyclonal antibody, detected by SDS-PAGE, purity should be >95%, concentration should be >5mg / mL) to 0.5mg / mL with HEPES buffer (solution b), add 30mL of the 0.5mg / mL diluted antibody to step (2), mix well, and place in a constant temperature shaker for 3h, temperature range: 30℃;

[0046] (4) Add 5 mL of blocking solution (10% BSA) to step (3), mix well, and place in a constant temperature shaker to react for 1 h. Temperature range: 30℃.

[0047] (5) After sealing, centrifuge the above solution in a refrigerated high-speed centrifuge with centrifugation parameters of 15,000 rpm and centrifugation time of 30 minutes. After centrifugation, remove the supernatant, add 300 mL of preservation solution to reconstitute, and sonicate to mix evenly for later use.

[0048] Example 2

[0049] The kit in this example includes reagent R1 and reagent R2, wherein the components of reagent R1 are:

[0050] Phosphate buffer: 100 mmol / L;

[0051] EDTA-2Na: 0.1 g / L;

[0052] Sodium chloride: 0.1 wt%;

[0053] Triton X-100: 0.7wt%;

[0054] Thioglycolic acid (first reducing agent): 0.5 wt%;

[0055] Potassium nitrite (second reducing agent): 2.0 wt%;

[0056] Sodium azide: 0.1 wt%;

[0057] The pH value is 7.0.

[0058] The composition and preparation method of reagent R2 in this example are the same as in Example 1.

[0059] Example 3

[0060] The kit in this example includes reagent R1 and reagent R2, wherein the components of reagent R1 are:

[0061] Tris: 150 mmol / L;

[0062] EDTA-2Na: 1.0 g / L;

[0063] Sodium chloride: 4 wt%;

[0064] Triton X-100: 1.0 wt%;

[0065] Mercaptopropionic acid (first reducing agent): 1.5 wt%;

[0066] Potassium phosphite (second reducing agent): 0.5 wt%;

[0067] Sodium azide: 0.1 wt%;

[0068] The pH value is 6.5.

[0069] The composition and preparation method of reagent R2 in this example are the same as in Example 1.

[0070] Example 4

[0071] The kit in this example includes reagent R1 and reagent R2, wherein the components of reagent R1 are:

[0072] Good's buffer: 200 mmol / L;

[0073] EDTA-2Na: 0.8 g / L;

[0074] Sodium chloride: 5 wt%;

[0075] Triton X-100: 0.1 wt%;

[0076] Mercaptopropionic acid (first reducing agent): 1.5 wt%;

[0077] Potassium hypophosphite (second reducing agent): 2.0 wt%;

[0078] Sodium azide: 0.1%;

[0079] The pH value is 7.5.

[0080] The composition and preparation method of reagent R2 in this example are the same as in Example 1.

[0081] Comparative Example 1

[0082] The kit in this example includes reagent R1 and reagent R2. The composition and preparation method of reagent R2 are the same as in Example 1. Reagent R1 does not contain the first reducing agent and the second reducing agent. The rest is the same as in Example 1.

[0083] Comparative Example 2

[0084] The kit in this example includes reagent R1 and reagent R2. The composition and preparation method of reagent R2 are the same as in Example 1. Reagent R1 does not contain a second reducing agent. The rest is the same as in Example 1.

[0085] Comparative Example 3

[0086] The kit in this example includes reagent R1 and reagent R2. The composition and preparation method of reagent R2 are the same as in Example 1. Reagent R1 does not contain the first reducing agent. The rest is the same as in Example 1.

[0087] Example 5

[0088] This example evaluates the performance of the kits in Examples 1-4. The instrument used in this example is a HITACHI 7100, and the specific experimental parameters are shown in Table 1.

[0089] Table 1

[0090] dominant wavelength 600nm subwavelength none Sample size 4μL R1 120μL R2 30μL Reaction direction positive reaction time 10min Calibration method Multi-point calibration

[0091] The specific performance evaluation methods are as follows:

[0092] (1) Accuracy: When measuring third-party quality control materials (serum matrix), calculate the deviation between the measured average value and the target value. Generally, it should be <10%.

[0093] (2) Sensitivity: Low concentration samples with MPO concentrations of 5 ng / mL, 10 ng / mL and 15 ng / mL were measured 10 times for each sample. The mean, standard deviation (SD), bias and coefficient of variation (CV) were calculated. The bias and CV should be less than 10%.

[0094] (3) Precision: Repeat the measurement of samples near the same reference value 10 times, and the coefficient of variation (CV) should generally be <10%;

[0095] (4) Evaluation of linear range: Samples with different concentrations of 0-1500 ng / mL were measured. Each concentration was measured three times. The mean theoretical value and relative deviation were calculated. The relative deviation of each point was within 10%, which meets the requirements of use.

[0096] (5) Thermal breakage stability: The reagent was placed at 37℃ for 7 days for thermal breakage. The evaluation was conducted after 7 days of thermal breakage. The evaluation indicators were: accuracy (%), sensitivity, precision (%) and linear range.

[0097] (6) Long-term stability: The reagent was placed at 2-8℃ for 24 months, and its performance was evaluated every 6 months. The evaluation indicators were: accuracy (%), sensitivity, precision (%) and linear range.

[0098] The final test results and their analysis are as follows:

[0099] 1. Using the kits of Comparative Examples 1-3 as the control group, the reagent performance test results of the Example and the control group were compared at month 0.

[0100] Table 2. Accuracy data for the example and control group in month 0.

[0101]

[0102]

[0103] As shown in Table 2, the accuracy deviations of several examples and Comparative Example 2 are small, meeting the requirements. The measured values ​​of Comparative Example 1 and Comparative Example 3 are significantly lower, with larger accuracy deviations, failing to meet the reagent performance requirements.

[0104] Table 3 Precision data of the example and control group at month 0

[0105] 1 128.2 130.9 130.6 124.7 116.0 127.0 118.4 2 131.6 129.8 131.8 127.8 115.5 128.1 114.3 3 129.8 130.4 131.0 124.7 123.3 126.9 134.3 4 127.3 125.7 126.5 128.4 110.0 129.2 115.1 5 125.2 125.4 128.0 125.2 118.8 131.6 111.8 6 126.2 124.9 127.7 127.0 113.8 126.8 116.8 7 127.9 125.6 132.0 131.0 120.7 131.7 133.0 8 127.0 129.0 129.5 127.6 135.3 127.5 117.8 9 124.7 126.2 127.9 125.7 138.2 126.7 117.0 10 124.6 127.7 130.6 127.0 128.5 125.8 110.4 mean 127.25 127.56 129.56 126.91 122.01 128.13 118.89 SD 2.252 2.291 1.921 1.955 9.337 2.065 8.190 CV 1.77％ 1.80％ 1.48％ 1.54％ 7.65％ 1.61％ 6.89％

[0106] As shown in Table 3, the precision CVs of several examples and Comparative Example 2 are relatively small, indicating good precision and meeting the reagent performance requirements. The precision CVs of Comparative Examples 1 and 3 are significantly higher, indicating poor precision.

[0107] Table 4 Sensitivity data for the example in month 0

[0108]

[0109]

[0110] Table 5. Sensitivity data of the control group in month 0.

[0111]

[0112] As can be seen from Tables 4 and 5, the measured values ​​of low-concentration samples in Comparative Examples 1 and 3 were too low, with the values ​​of 5 ng / mL, 10 ng / mL, and 15 ng / mL all being 30% lower, and the precision CVs were also large, all exceeding 10%. In contrast, the deviations of the low-concentration samples in the examples and Comparative Example 2 were all less than 5%, and the precision CVs were also low, indicating that the examples and Comparative Example 2 had higher sensitivity, reaching 5 ng / mL.

[0113] Table 6 Linear data for the example and control group at month 0

[0114]

[0115]

[0116] The data above show that the linearity of all the examples and the control group can be measured at 1500 ng / mL, and the linear correlation is good. There is no difference in the linear performance between the examples and the control group.

[0117] Based on the accuracy, precision, sensitivity, and linearity data from month 0, Comparative Examples 1 and 3 showed lower measured values ​​but higher precision CVs. The measured values ​​for low-concentration samples were significantly lower with larger CVs. Examples 1-4 and Comparative Example 2 demonstrated significantly better accuracy and precision than Comparative Examples 1 and 3, with smaller deviations and better CVs for low-concentration samples. Sensitivity was also improved compared to Comparative Examples 1 and 3, reaching 5 ng / mL without affecting linearity, which remained at 1500 ng / mL. The accuracy, precision, sensitivity, and linearity of Examples 1-4 and Comparative Example 2 meet clinical application requirements.

[0118] 2. Using the kit of Comparative Example 2 as the control group, the thermal breakdown stability test results of Examples 1-4 and the control group were compared.

[0119] Table 7. Reagent accuracy data of the Example and Control Group before and after 7 days of heat destruction at 37°C.

[0120]

[0121] Table 8. Reagent precision data of the examples and control group before and after 7 days of heat destruction at 37°C.

[0122]

[0123]

[0124] Table 9. Reagent sensitivity data of the examples and control group before and after 7 days of heat destruction at 37°C.

[0125]

[0126] Table 10. Reagent linearity data before and after 7 days of heat destruction at 37°C for the examples and control group.

[0127]

[0128]

[0129] As shown in Table 7-10, the accuracy, precision, sensitivity, and linearity of the several examples before and after heat-breaking showed no significant changes and all met the requirements. The accuracy, precision, sensitivity, and linearity of Comparative Example 2 reagent before heat-breaking were not significantly different from the examples. However, after heat-breaking at 37℃ for 7 days, the accuracy of Control Group 2 was lower, the precision CV increased, the number of low-value samples tested was significantly lower, the CV increased, the sensitivity decreased, and the linearity remained unchanged. This indicates that the accuracy, precision, and sensitivity of Comparative Example 2 reagent changed and became unstable after heat-breaking at 37℃ for 7 days.

[0130] 3. Using the kit of Comparative Example 2 as the control group, the long-term stability test results of Examples 1-4 and the control group were compared.

[0131] Table 11 Long-term stability of accuracy between the examples and the control group

[0132] Example 1 -1.27％ 2.15％ 1.64％ 1.89％ 1.25％ Example 2 0.89％％ 1.56％ 1.18％ 1.47％ -0.96％ Example 3 -0.29％ 1.15％ 0.85％ 1.69％ 1.45％ Example 4 0.25％ 1.37％ 1.52％ 1.75％ -2.10％ Comparative Example 2 -0.40％ -3.60％ -7.82％ -10.59％ -13.61％

[0133] Table 12. Long-term stability of precision in the examples and control group.

[0134] Example 1 1.77％ 1.26％ 1.48％ 1.16％ 1.25％ Example 2 1.80％ 1.35％ 1.25％ 1.08％ 1.28％ Example 3 1.48％ 1.28％ 1.47％ 1.34％ 1.45％ Example 4 1.54％ 1.64％ 1.16％ 1.14％ 1.52％ Control group 2 1.61％ 3.69％ 5.21％ 7.52％ 8.12％

[0135] Table 13. Long-term stability of sensitivity in the examples and control group

[0136]

[0137]

[0138] Table 14. Linear long-term stability of the examples and control group

[0139]

[0140] As shown in Tables 11-14, the accuracy, precision, sensitivity, and linearity of the reagents in each example remained stable after 24 months of storage. For Comparative Example 2, the accuracy, precision, sensitivity, and linearity were not significantly different from the examples at month 0. After 24 months of storage, the accuracy of Comparative Example 2 decreased, the precision CV increased, the low-value samples tested showed lower accuracy and increased CV, the sensitivity decreased, and the linearity of high-value samples decreased slightly, while the linear correlation coefficient remained relatively stable. This indicates that the accuracy, precision, and sensitivity of Comparative Example 2 changed after 24 months of storage, indicating instability.

[0141] In summary, by adding a first reducing agent (mercaptoacetic acid, mercaptopropionic acid, mercaptoacetate, mercaptopropionate) to reagent R1 of the myeloperoxidase detection kit (latex immunoturbidimetric assay), this invention can effectively ensure small accuracy deviation, good precision, and significantly improved sensitivity of the reagent without affecting its linear range. Furthermore, by adding a second reducing agent (sulfite, nitrite, phosphite, hypophosphite) to reagent R1, the thermal stability and long-term stability of the kit can be effectively improved, enabling it to better meet clinical needs.

[0142] The upper and lower limits and ranges of the substances listed in this invention, as well as the upper and lower limits and ranges of the preparation process parameters, can all realize this invention, and will not be listed one by one here.

[0143] The above description is a preferred embodiment of the present invention and should not be construed as limiting the scope of the present invention. It should be noted that any modifications, equivalent substitutions, and improvements made by those skilled in the art within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A high sensitivity myeloperoxidase latex turbidimetric assay kit characterized in that, The kit includes reagent R1 and reagent R2. Reagent R1 comprises: 100-200 mmol / L buffer, 0.1-1.0 g / L EDTA-2Na, 0.1-5 wt% sodium chloride, 0.1-1.0 wt% Triton X-100, 0.5-1.5 wt% first reducing agent, and 0.5-2.0 wt% second reducing agent. The pH of reagent R1 is 6.5-7.

5. The buffer is Good's buffer, Tris buffer, or phosphate buffer. The first reducing agent is one of mercaptoacetic acid, mercaptopropionic acid, mercaptoacetate, and mercaptopropionate. The second reducing agent is one of sulfite, nitrite, phosphite, and hypophosphite. The R2 reagent consists of a preservation solution and latex microspheres conjugated with myeloperoxidase antibody. The preservation solution comprises 20-50 mmol / L Good's buffer, 0.5-1.5 wt% sodium chloride, 0.05-0.15 wt% sodium azide, 0.05-0.5 wt% Tween-20, and 0.5-5 wt% trehalose, with a pH of 7.0-7.

5.

2. The myeloperoxidase latex turbidimetric assay kit according to claim 1, characterized in that, The mercaptoacetate is sodium mercaptoacetate or potassium mercaptoacetate; the mercaptopropionate is sodium mercaptopropionate or potassium mercaptopropionate; the sulfite is one of sodium sulfite, potassium sulfite, ammonium sulfite, sodium bisulfite, potassium bisulfite, and ammonium bisulfite; the nitrite is sodium nitrite or potassium nitrite; the phosphite is one of sodium phosphite, potassium phosphite, calcium phosphite, and zinc phosphite; and the hypophosphite is one of sodium hypophosphite, potassium hypophosphite, magnesium hypophosphite, and calcium hypophosphite.

3. The myeloperoxidase latex turbidimetric assay kit according to claim 1, characterized in that, The preparation method of latex microspheres conjugated with myeloperoxidase antibody is as follows: take latex microspheres and add them to activation buffer, then add EDC for activation; dilute myeloperoxidase antibody with conjugation buffer, and then conjugate it with the activated latex microspheres; after the conjugation is completed, add blocking solution; after the blocking is completed, centrifuge and remove the supernatant to obtain the product.

4. The myeloperoxidase latex turbidimetric assay kit according to claim 3, characterized in that, The latex microspheres have a particle size of 150-250 nm.

5. The myeloperoxidase latex turbidimetric assay kit according to claim 3, wherein The sealing liquid is 10-20 wt% BSA.

6. The myeloperoxidase latex turbidimetric assay kit according to claim 3, wherein The activation buffer is a 10-50 mmol / L MES buffer with pH 5.0-6.0, and the coupling buffer is a 10-50 mmol / L HEPES buffer with pH 7.0-8.

0.

7. A high sensitivity latex turbidimetric assay for myeloperoxidase characterized in that, The detection is performed using the myeloperoxidase latex turbidimetric assay kit according to any one of claims 1-6, and the detection is not for the purpose of diagnosing or treating a disease.

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