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*It is only for medical professionals to read for reference.
HLA-B27 positive is more likely to suffer from axial spondylitis than negative HLA-B27.
Speaking of HLA-B27, many patients with ankylosing spondylitis (AS) must be familiar with it and doubt it by clinicians.
When it is a type of disease such as axial spondyloarthritis, one of the tests often prescribed is it.
What is it and what does it have to do with axial spondyloarthritis? 01 What is HLA-B27? Human Leukocyte Antigen (HLA) is the expression product of human major histocompatibility complex.
It is mainly responsible for mutual recognition between cells and inducing immune response in the immune system, and presents endogenous antigens to cytotoxic T Cells to regulate the immune response.
According to the different structure, function and tissue distribution of HLA antigens, it can be divided into three categories, category I (including HLA-A, -B, -C three antigens), category II and category III.
Among them, type I molecules are widely distributed on the surface of nucleated cells in various tissues, type II molecules are mainly expressed on B cells and antigen-presenting cells, and type III molecules are complement components.
HLA-B27 belongs to the class I (human histocompatibility complex) MCH gene, which is widely distributed in nucleated cells, especially on the surface of lymphocytes.
As of 2018, there are 167 subtypes of HLA-B27 reported in the world.
The distribution of these different subtypes differs in region and ethnicity, and their association with diseases is also different.
Among them, HLA-B27: 05 is the most common subtype.
HLA-B27:05 accounts for 96% of whites, HLA-B27:03 is the main subtype of African blacks, and HLA-B27:04 and HLA-B27:05 subtypes are common among Chinese [1- 2].
02 Detection of HLA-B27, four methods to understand the current detection methods for HLA-B27 mainly include complement-dependent cytotoxicity, enzyme-linked immunosorbent assay, flow cytometry and PCR.
As clinicians, we do not need to master the specific operations of each method, but the sensitivity and specificity of different methods still need to be understood.
In summary, the complement-dependent cytotoxicity method is the earliest method used to detect HLA-B27, but because the detection conditions are difficult to control, most of them are not used now; the enzyme-linked immunosorbent method is simple and fast in operation, suitable for most small and medium-sized hospitals and large samples The census; flow cytometry is the easiest, most automated, and reproducible method of all methods.
It has strong sensitivity and specificity (about 95%).
This method is regarded as HLA- The conventional detection method of B27 has not been implemented in many domestic hospitals because of the expensive equipment.
The PCR method has gradually been recognized in recent years and has significant advantages in the detection of carriers of the HLA-B27 gene with weakly expressed antigens.
When experimental conditions permit, it is recommended that flow cytometry and PCR methods complement the detection to improve accuracy [2 ].
In addition, it is added that in the detection of HLA-B27, blood samples should be tested within 24 hours after collection [3].
Some studies have shown that as the sample collection time increases, the accuracy of the test results decreases.
03 Is HLA-B27 positive, must it be AS? 1AS said so much what HLA-B27 is, so what is the relationship between its positive and disease? It is well known that genetic factors play an important role in the pathogenesis of AS.
As early as 1973, studies confirmed that there is a strong association between HLA-B27 positive and AS [4].
So far, the relationship between HLA-B27 and AS It is the strongest and most typical association between HLA and disease.
The positive rate of HLA-B27 in the normal population is about 5%, and the positive rate of HLA-B27 in AS patients is about 90%.
And in the survey of first-degree relatives of AS patients, it was found that HLA-B27 positive accounted for 31.
3%, and the risk of AS was 10.
8 times higher than normal family controls [5].
2 Anterior uveitis In addition to AS, HLA-B27 positive has a strong correlation with anterior uveitis, which accounts for approximately 50% of patients with acute anterior uveitis.
HLA-B27-related anterior uveitis is typically manifested as sudden onset, unilateral anterior uveitis, which can show photophobia, tearing, red eyes, eye pain, blurred vision, etc.
The prevalence of men is 1.
5-2.
5 times that of women It is worth noting that HLA-B27-positive patients with acute anterior uveitis are often more likely to relapse, and about 50%-75% of patients with anterior uveitis are accompanied by axial spondyloarthritis [6].
This also suggests that clinicians such as ophthalmologists who encounter severe unilateral or bilateral anterior uveitis should perform HLA-B27 testing and consider whether they are associated with rheumatism, while rheumatologists should pay attention Ocular lesions that may occur during the course of patients with axial spondyloarthritis.
As mentioned earlier, the associations between different subtypes of HLA-B27 and diseases are also different.
Studies have shown that HLA-B27:04 has the strongest association with AS, followed by HLA-B27:05, while HLA-B27:06, HLA-B27 : 09 is considered a protective gene.
The low incidence of AS in Malaysians may be related to the protective effect of HLA-B27:06 [2].
The proportion of patients with HLA-B27:05 subtype AS associated with uveitis is significantly higher.
In HLA-B27:04 subtype AS patients [7].
04 Summary In summary, we can see that HLA-B27 positive and AS cannot be completely equated, and some healthy people are also HLA-B27 positive, and about 10% of AS patients are also negative for HLA-B27, HLA-B27 A negative does not completely rule out the possibility of ankylosing spondylitis, but a positive HLA-B27 is more likely to suffer from axial spondylitis than a negative.
References: [1]Dashti N, Mahmoudi M, Aslani S, Jamshidi A.
HLA-B*27 subtypes and their implications in the pathogenesis of ankylosing spondylitis.
Gene.
2018 Sep 5;670:15-21.
doi: 10.
1016/ j.
gene.
2018.
05.
092.
Epub 2018 May 24.
PMID: 29803000.
[2]Bai Shijie,Tuoya,Zhang Baoping,Wang Lijuan,Wang Yafei.
Research status of ankylosing spondylitis and its related gene HLA-B27 detection[J] .
Journal of Molecular Diagnosis and Therapy,2016,8(03):206-211.
[3]Yan Haidong,Wang Ke,Gao Haizhen.
The effect of storage time on the accuracy of detection results of human leukocyte antigen-B27[J].
Journal of Practical Clinical Medicine ,2020,24(15):11-13.
[4]Brewerton DA, Hart FD, Nicholls A, Caffrey M, James DC, Sturrock RD.
Ankylosing spondylitis and HL-A 27.
Lancet.
1973 Apr 28;1(7809 ):904-7.
doi: 10.
1016/s0140-6736(73)91360-3.
PMID: 4123836.
[5]Dougados M, Baeten D.
Spondyloarthritis[J].
Lancet, 2011, 377(9783): 2127-2137 .
[6]Kopplin LJ, Mount G, Suhler EB.
Review for Disease of the Year: Epidemiology of HLA-B27 Associated Ocular Disorders.
Ocul Immunol Inflamm.
2016 Aug;24(4):470-5.
doi: 10.
1080/09273948.
2016 .
1175642.
Epub 2016 May 27.
PMID: 27232197; PMCID: PMC6733982.
[7] Liu Qian, Ma Liang, Yue Debo, Liu Hui, Jiang Yongwei, Xu Yingchun.
HLA-B27 genotyping and clinical characteristics analysis of patients with ankylosing spondylitis[J].
Journal of Japanese Friendship Hospital, 2020, 34(05):271-273+278.
HLA-B27 positive is more likely to suffer from axial spondylitis than negative HLA-B27.
Speaking of HLA-B27, many patients with ankylosing spondylitis (AS) must be familiar with it and doubt it by clinicians.
When it is a type of disease such as axial spondyloarthritis, one of the tests often prescribed is it.
What is it and what does it have to do with axial spondyloarthritis? 01 What is HLA-B27? Human Leukocyte Antigen (HLA) is the expression product of human major histocompatibility complex.
It is mainly responsible for mutual recognition between cells and inducing immune response in the immune system, and presents endogenous antigens to cytotoxic T Cells to regulate the immune response.
According to the different structure, function and tissue distribution of HLA antigens, it can be divided into three categories, category I (including HLA-A, -B, -C three antigens), category II and category III.
Among them, type I molecules are widely distributed on the surface of nucleated cells in various tissues, type II molecules are mainly expressed on B cells and antigen-presenting cells, and type III molecules are complement components.
HLA-B27 belongs to the class I (human histocompatibility complex) MCH gene, which is widely distributed in nucleated cells, especially on the surface of lymphocytes.
As of 2018, there are 167 subtypes of HLA-B27 reported in the world.
The distribution of these different subtypes differs in region and ethnicity, and their association with diseases is also different.
Among them, HLA-B27: 05 is the most common subtype.
HLA-B27:05 accounts for 96% of whites, HLA-B27:03 is the main subtype of African blacks, and HLA-B27:04 and HLA-B27:05 subtypes are common among Chinese [1- 2].
02 Detection of HLA-B27, four methods to understand the current detection methods for HLA-B27 mainly include complement-dependent cytotoxicity, enzyme-linked immunosorbent assay, flow cytometry and PCR.
As clinicians, we do not need to master the specific operations of each method, but the sensitivity and specificity of different methods still need to be understood.
In summary, the complement-dependent cytotoxicity method is the earliest method used to detect HLA-B27, but because the detection conditions are difficult to control, most of them are not used now; the enzyme-linked immunosorbent method is simple and fast in operation, suitable for most small and medium-sized hospitals and large samples The census; flow cytometry is the easiest, most automated, and reproducible method of all methods.
It has strong sensitivity and specificity (about 95%).
This method is regarded as HLA- The conventional detection method of B27 has not been implemented in many domestic hospitals because of the expensive equipment.
The PCR method has gradually been recognized in recent years and has significant advantages in the detection of carriers of the HLA-B27 gene with weakly expressed antigens.
When experimental conditions permit, it is recommended that flow cytometry and PCR methods complement the detection to improve accuracy [2 ].
In addition, it is added that in the detection of HLA-B27, blood samples should be tested within 24 hours after collection [3].
Some studies have shown that as the sample collection time increases, the accuracy of the test results decreases.
03 Is HLA-B27 positive, must it be AS? 1AS said so much what HLA-B27 is, so what is the relationship between its positive and disease? It is well known that genetic factors play an important role in the pathogenesis of AS.
As early as 1973, studies confirmed that there is a strong association between HLA-B27 positive and AS [4].
So far, the relationship between HLA-B27 and AS It is the strongest and most typical association between HLA and disease.
The positive rate of HLA-B27 in the normal population is about 5%, and the positive rate of HLA-B27 in AS patients is about 90%.
And in the survey of first-degree relatives of AS patients, it was found that HLA-B27 positive accounted for 31.
3%, and the risk of AS was 10.
8 times higher than normal family controls [5].
2 Anterior uveitis In addition to AS, HLA-B27 positive has a strong correlation with anterior uveitis, which accounts for approximately 50% of patients with acute anterior uveitis.
HLA-B27-related anterior uveitis is typically manifested as sudden onset, unilateral anterior uveitis, which can show photophobia, tearing, red eyes, eye pain, blurred vision, etc.
The prevalence of men is 1.
5-2.
5 times that of women It is worth noting that HLA-B27-positive patients with acute anterior uveitis are often more likely to relapse, and about 50%-75% of patients with anterior uveitis are accompanied by axial spondyloarthritis [6].
This also suggests that clinicians such as ophthalmologists who encounter severe unilateral or bilateral anterior uveitis should perform HLA-B27 testing and consider whether they are associated with rheumatism, while rheumatologists should pay attention Ocular lesions that may occur during the course of patients with axial spondyloarthritis.
As mentioned earlier, the associations between different subtypes of HLA-B27 and diseases are also different.
Studies have shown that HLA-B27:04 has the strongest association with AS, followed by HLA-B27:05, while HLA-B27:06, HLA-B27 : 09 is considered a protective gene.
The low incidence of AS in Malaysians may be related to the protective effect of HLA-B27:06 [2].
The proportion of patients with HLA-B27:05 subtype AS associated with uveitis is significantly higher.
In HLA-B27:04 subtype AS patients [7].
04 Summary In summary, we can see that HLA-B27 positive and AS cannot be completely equated, and some healthy people are also HLA-B27 positive, and about 10% of AS patients are also negative for HLA-B27, HLA-B27 A negative does not completely rule out the possibility of ankylosing spondylitis, but a positive HLA-B27 is more likely to suffer from axial spondylitis than a negative.
References: [1]Dashti N, Mahmoudi M, Aslani S, Jamshidi A.
HLA-B*27 subtypes and their implications in the pathogenesis of ankylosing spondylitis.
Gene.
2018 Sep 5;670:15-21.
doi: 10.
1016/ j.
gene.
2018.
05.
092.
Epub 2018 May 24.
PMID: 29803000.
[2]Bai Shijie,Tuoya,Zhang Baoping,Wang Lijuan,Wang Yafei.
Research status of ankylosing spondylitis and its related gene HLA-B27 detection[J] .
Journal of Molecular Diagnosis and Therapy,2016,8(03):206-211.
[3]Yan Haidong,Wang Ke,Gao Haizhen.
The effect of storage time on the accuracy of detection results of human leukocyte antigen-B27[J].
Journal of Practical Clinical Medicine ,2020,24(15):11-13.
[4]Brewerton DA, Hart FD, Nicholls A, Caffrey M, James DC, Sturrock RD.
Ankylosing spondylitis and HL-A 27.
Lancet.
1973 Apr 28;1(7809 ):904-7.
doi: 10.
1016/s0140-6736(73)91360-3.
PMID: 4123836.
[5]Dougados M, Baeten D.
Spondyloarthritis[J].
Lancet, 2011, 377(9783): 2127-2137 .
[6]Kopplin LJ, Mount G, Suhler EB.
Review for Disease of the Year: Epidemiology of HLA-B27 Associated Ocular Disorders.
Ocul Immunol Inflamm.
2016 Aug;24(4):470-5.
doi: 10.
1080/09273948.
2016 .
1175642.
Epub 2016 May 27.
PMID: 27232197; PMCID: PMC6733982.
[7] Liu Qian, Ma Liang, Yue Debo, Liu Hui, Jiang Yongwei, Xu Yingchun.
HLA-B27 genotyping and clinical characteristics analysis of patients with ankylosing spondylitis[J].
Journal of Japanese Friendship Hospital, 2020, 34(05):271-273+278.
