Background
Antibodies to human neutrophil alloantigens (HNA) are involved in the pathophysiology of several clinical conditions including transfusion-related acute lung injury (TRALI), alloimmune and autoimmune neutropenia, and febrile nonhemolytic transfusion reactions leading to neutropenia. The cognate antigens are polymorphic structures expressed on several glycoproteins on the neutrophils, i.e., antigens HNA-1a, -1b, -1c, and -1d on Fc-γ-receptor IIIb; HNA-2 on CD177; HNA-3a and -3b on choline transporter-like protein 2; HNA-4a and -4b on CD11b/αM subunit of the αMβ2-integrin (CD11b/CD18, Mac-1, CR3); and HNA-5a and -5b on αL-subunit (CD11a) of the αLβ2 integrin (CD11a/CD18), leukocyte function associated molecule (LFA)-1. Currently, there is a lacuna of diagnostic
Conclusion
This is the first study in India to report the frequencies of HNA among blood donors. Typed neutrophil panels identified in the present study will enable us to investigate suspected cases of immune neutropenia in future.
Material and methods
EDTA blood samples were collected from random 1,054 blood donors. HNA-2 was phenotyped on fresh EDTA samples using FITC labelled monoclonal anti-CD177 by flowcytometry. HNA-1 (FCGR3B) genotyping was carried out by DNA sequencing and PCR-RFLP. Antigens of HNA-3 (SLC44A2) and HNA-5 (ITGAL) were genotyped by PCR-RFLP using TaqαI and Bsp1286I restriction enzymes, respectively, while HNA-4 (ITGAM) was genotyped by PCR-SSP.
Methods
EDTA blood samples were collected from random 1,054 blood donors. HNA-2 was phenotyped on fresh EDTA samples using FITC labelled monoclonal anti-CD177 by flowcytometry. HNA-1 (FCGR3B) genotyping was carried out by DNA sequencing and PCR-RFLP. Antigens of HNA-3 (SLC44A2) and HNA-5 (ITGAL) were genotyped by PCR-RFLP using TaqαI and Bsp1286I restriction enzymes, respectively, while HNA-4 (ITGAM) was genotyped by PCR-SSP.
Results
Allele frequencies of FCGR3B*01, FCGR3B*02, and FCGR3B*03 were found to be 0.433, 0.444, and 0.087, respectively. FCGR3B*01+*02+*03- was the most common genotype (33.78%). Ten individuals showed deficiency of FCGR3B individuals, while 23 showed hyperexpression, i.e., FCGR3B*01+*02+*03+. FCGR3B*04and *05 occurred with a frequency of 0.002 and 0.024. HNA-2 was found to be a high frequency antigen occurring in 98.8% population. Four percent individuals showed atypical expression of CD177 on their neutrophils. Allele frequencies of SLC44A2*01 and SLC44A2*02were 0.812 and 0.188, respectively, and that of ITGAM*01, ITGAM*02, ITGAL*01, and ITGAL*02 were 0.9546, 0.0454, 0.2372, and 0.7628, respectively.