|Year : 2021 | Volume
| Issue : 1 | Page : 28-32
Prevalence of ABO blood group phenotypes and antibody titers of the blood donor population in and around Puducherry
Sridhar Gopal, Sujitha Kannan, Rajendra Kulkarni, Abhishekh Basavarajegowda
Department of Transfusion Medicine, Jawaharlal Institute of Postgraduate Medical Education and Research, Puducherry, India
|Date of Submission||12-Jan-2021|
|Date of Decision||04-May-2021|
|Date of Acceptance||18-May-2021|
|Date of Web Publication||30-Jun-2021|
Room No 5042, Superspeciality Block, Jawaharlal Institute of Postgraduate Medical Education and Research, Puducherry
Source of Support: None, Conflict of Interest: None
Background: For any blood transfusion services, knowing the prevalence and distribution of blood groups in their corresponding geographical area is essential. Hence, this study was done to know the prevalence and distribution of the ABO blood group and the antibody titer levels of blood donors at a premier tertiary care center in Southern India. Methodology: This was a cross-sectional study conducted over 22 months from September 2015 to June 2017 in the Department of Transfusion Medicine, JIPMER, Puducherry, among blood donors in a single tertiary care teaching hospital blood center. The ABO blood group and Rhesus factors (Rh) were determined by the antigen-antibody agglutination test by the test tube method. Titration of anti-A and anti-B antibodies was also done for selected “O” group donors by the doubling dilution technique in the tube method. Results: It was found that the most common blood group in our blood donor population was the “O” blood group with 11,904 (38.43%) followed by “B” 10,643 (34.37%), “A” 6,201 (20.02%), and “AB” 2,219 (7.17%). We had 4 Bombay blood group donors during the study period (0.01%). A titer of 1:32 was the most frequently encountered for IgM anti-A and anti-B antibodies; in Group “O” donors and IgG antibodies, it was 1:8. Conclusion: The prevalence of ABO in and around Puducherry is comparable to those published from other regions in Southern India, with the “O” group being the most common. The distribution of antibody titers for anti-A and anti-B is similar to other studies in India.
Keywords: ABO prevalence, antibody titers, Puducherry
|How to cite this article:|
Gopal S, Kannan S, Kulkarni R, Basavarajegowda A. Prevalence of ABO blood group phenotypes and antibody titers of the blood donor population in and around Puducherry. Int J Adv Med Health Res 2021;8:28-32
|How to cite this URL:|
Gopal S, Kannan S, Kulkarni R, Basavarajegowda A. Prevalence of ABO blood group phenotypes and antibody titers of the blood donor population in and around Puducherry. Int J Adv Med Health Res [serial online] 2021 [cited 2022 Jul 3];8:28-32. Available from: https://www.ijamhrjournal.org/text.asp?2021/8/1/28/319772
| Introduction|| |
Karl Landsteiner (1900) discovered the ABO blood group system. New blood groups have been discovered and regularly added with 43 blood group systems currently registered by the International Society of Blood Transfusion. However, ABO remains the most important of all blood group systems and ABO blood grouping, and Rh D typing is mandatory for all blood donors and patients undergoing transfusion. In most developing countries, including India, only the ABO and Rh (D) status of blood donors and recipients are considered for pretransfusion testing during a blood transfusion. Although the transfusion of plasma-containing blood products usually happens within the ABO compatible groups, it may not always be possible to get the required group-specific blood products. While giving ABO-incompatible plasma transfusion in case of emergencies or nonavailability of the compatible group, especially platelets, it is imperative to ensure the titers of antibodies, especially the “O” blood group, which are generally considered as universal donor products.
Our blood bank collects blood from donors from Puducherry and surrounding areas of Tamil Nadu as well as different places in India. There is scanty literature on the prevalence of blood groups in this area as there are studies done on tiny populations and particular sects/tribes only. This study aimed to describe the prevalence of ABO blood group phenotypes and the titers of anti-A and anti-B antibodies in Group O donors attending the blood bank at JIPMER. This study will also help in knowing the needs of the population in terms of blood requirement estimation. There are no studies that have studied IgM and IgG titers separately in India. We also tried to see if there is any difference in the prevalence of titer levels in donors from various geographical locations as the environmental factors, cultural differences, and existing climatic conditions are known to influence the titers.,
| Methodology|| |
Study design and population
This was a cross-sectional study conducted over 22 months from September 2015 to June 2017 in the Department of Transfusion Medicine, JIPMER, Puducherry. All healthy donors who have donated at our blood bank after screening and fitness according to departmental standard operating procedures and National Blood transfusion guidelines during the study period were included in the study. All blood units tested positive for transmissible transfusion infections, quantity not sufficient due to incomplete donation, atypical, and autoantibody positivity after screening were excluded from the study.
Determination of ABO blood group and Rhesus factors (Rh) was done by the antigen-antibody agglutination test using the test tube method. We used commercially prepared monoclonal antisera anti-A, anti-B, anti-AB, anti-D, and lectins anti-A1 and anti-H from Tulip diagnostics (Verna, Goa, India) for forward grouping.
Sample size and sampling
The sample size was estimated using the statistical formula for estimating a proportion. With an expected prevalence of high titer anti-A and anti-B antibodies as 58% from available literature (average of 54% and 62% for anti-A and anti-B, respectively) at 4% absolute precision and 95% confidence interval, for a population size of 11,904 “O” group donors, the sample size was estimated to be 560. Five hundred and sixty of the “O” group donors were chosen by systematic random sampling by choosing every fifth “O” donor. The antibody titration was performed on these donors.
Titration of anti-A and anti-B antibodies was done by the doubling dilution technique. The tubes are serially read, and the last tube showing a 1+ agglutination macroscopically is considered the titer of that antibody. This method was used for identification of both IgM and IgG titers. IgM titers were assessed at room temperatures, whereas IgG titers were assessed at 37°C with antihuman globulin technique after dithiothreitol (DTT) treatment at a concentration of 0.01 M (0.154 g of DTT dissolved in 100 ml of phosphate-buffered saline adjusted to a pH of 7.3). Titers above 1:64 were considered high titered antibodies. Quality was checked with appropriate controls for these antisera every day and with every new lot.
Data collection and analysis
The data on blood group distribution, Rh status, phenotypes, gender, and all other categorical data were expressed as frequency and percentages. All the data accumulation and analysis were done on Microsoft Excel.
Consent and ethics review
A written consent was obtained from all the participants requiring titration using a form with Participant Information Sheet designed in both English and Tamil. Institutional Ethics Committee approved the study vide letter no JIP/IEC/SC/2015/19/799 dated August 26, 2015.
| Results|| |
A total of 30,971 donors were analyzed for their blood groups in the study. Age group, 18–40 years, contributed 87.82% (27,199) of overall donation. Maximum donations were seen in the age group of 20–30 years with 40.19% (12,448), and least was from age group >50 years with 3.19% (987). Male donors contributed 96.38% (29,853) of the overall collection. The demographic characteristics of the donors are summarized in [Table 1].
The most common blood group in our blood donor population was the “O” blood group with 11,904 (38.43%), followed by “B” 10,643 (34.37%), “A” 6,201 (20.02%), and “AB” 2,219 (7.17%). We had 4 Bombay blood group donors during the study period (0.01%). The Rh (D) positive prevalence was 93.65% (29,005) and Rh (D) negative was 6.35% (1966) in our blood donor population. The groupwise distribution of various blood phenotypes is summarized in [Table 2]. The subgroups of the blood Group “A” are summarized in [Table 3].
|Table 2: Distribution of ABO and Rh” D” phenotypes amongst the donor population|
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During the study period, 11904 O group donors donated at the blood bank. IgG and IgM titration studies were done for anti-A and anti-B antibodies in 560 randomly chosen samples. Forward grouping and reverse grouping revealed no grouping discrepancies, and all samples were unequivocally identified as Group O. The grading of reactions for anti-H in the forward grouping and that of the serum grouping with A cells and B cells consistently gave a reaction of 3 + and above.
IgM titers anti-A and anti-B antibody titers
The highest titers recorded were 1:2048 in 6 samples. Among the titers recorded, a titer of 1:32 was the most frequently encountered in 100 samples, which constituted 22.8% for anti-A and 20% for anti-B of all samples tested. The distribution of titers of IgM and IgG anti-A and anti-B are depicted in [Figure 1] and [Figure 2].
IgG anti-A and anti-B antibody titers
After treating these 560 samples with DTT, only 145 samples showed the presence of IgG antibodies. IgG titers of anti-A and anti-B antibodies were tested with a similar double dilution pattern described for IgM in these 145 samples, which were hemolysin test positive. 9.6% of samples for anti-A and 5.5% for anti-B of all samples showed a critical titer of 1:256 or higher, the highest titer reaching 1:1024 in 1 sample for anti-A and 1:512 for one sample. The most common IgG titer was 1:8 as encountered for both anti-A and anti-B in 44.1% and 66.2% of the samples, respectively. Critical titers of 1:64 or higher were considered high titered antibodies for IgM anti-A and anti-B. The distribution of high titer anti-A or anti-B antibodies with respect to the location is shown in [Table 4].
|Table 4: Location-wise prevalence of donors of high titred anti-A, anti-B antibodies|
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| Discussion|| |
ABO is the first and foremost check for transfusion of all blood products. Transfusions of blood products should be ABO specific. If not, as in certain situations, when the identical blood group is not available, it should always be compatible. Thus, the ABO blood group's frequency and distribution is the single most important determinant in any population when concerned with blood transfusion. This not only determines the antigenic prevalence in that population but also the availability of blood products for transfusion.
For any blood transfusion services to recruit voluntary donors, the distance of the donor from the concerned blood bank forms a significant concern for easy accessibility. Our hospital is a tertiary care hospital, and we receive patients from all over India, but most of the donors are from a distance that is not too far from the location of the blood bank. Based on the distance-wise distribution, we found that predominantly donors are from a distance <50 kms, which contributed 91.57% (28,361) of the sample.
Knowledge of the prevalence and distribution of ABO and Rh blood group in donors is essential for effective inventory management of the blood banks. The frequency and distribution of ABO, Rh (D), and other blood groups vary in different populations depending on their race, ethnicity, and geographical distribution.
Most of the studies from South India show that “O” is the most common blood group, which is followed by “B,” which is similar to the present study.,, The exception is the study from Salem by Anumanthan et al., which showed that “B” is the most common, followed by the “O” blood group. It may be attributed to the reason that Salem is a place with a lot of industries, where migration of people is more common.
In another study conducted by Subhashini, in Pondicherry, it was found that the B blood group (39.5%) was the most common, followed by the O blood group (34%), and the prevalence of the ABO blood group is B > O> A > AB. This study was conducted in the Irulas tribal population in and around Pondicherry and with only a sample size of 200. Hence, both studies differed and cannot be compared.
The overall prevalence of blood groups in India is 23.16%, 34.10%, 34.56%, and 8.18%, respectively, for A, B, O, and AB. Our prevalence is vastly comparable to this except for a slightly higher prevalence for the O group in our population. Rh (D)-positive and Rh (D)-negative population are 94.13% and 5.87%, respectively, in India, which is almost similar in our study population. Being a hospital-based study, it could also be possible that a higher number of O group donors come for donation as it is a universal donor group.
O blood group dominance in southern India has also been explained by the “Malaria theory” for Haldane which postulates that blood group O confers protection against severe malaria due to plasmodium falciparum. They are not suitable for rosette formation, leading to a specific selection of these populations in certain geographic locations.
Most of the studies from India did not subgroup “A” blood group donors. A study from Delhi, National Capital Region (NCR), where “A2” was reported, was compared and found that the prevalence of A2 was 6.71%, which is consistent with findings from the present study. The potency of the lectin used has an implication for the identification of these subgroups. The differentiation is important because few A2 patients, up to 8%, may have antibodies against the A1.
Since “O” blood group individuals are named as “Universal Donors,” the population with a maximum “O” blood group will be very much beneficial in cases of emergency and disasters when getting group-specific donors is not possible.
Blood banks are burdened with the perennial task of balancing a precarious inventory, especially platelets since they have a short shelf life of 5 days, and a capricious demand. Hence in many situations, it is challenging to provide ABO-matched platelets to all recipients and O being a more common group, the inventory also would be comparatively having more of “O” products. However, knowledge regarding the prevalent antibody titers is essential because high titers of antibodies, i.e. >1 in 64, can give rise to hemolysis of the red cells in recipients due to minor incompatibility.,
In a study done by Tendulkar et al. in western India, the median titers noted was 1 in 128. The baseline infection rates in the population, vaccination rates, and other unknown environmental factors are responsible for the variation in the prevalence of antibody titers. Studies done in various regions have shown a wide variation in prevalence due to these uncharacterized environmental factors. Interestingly, donors who have titers congruent with the prevalence in their region develop titers congruent with the region of emigration, in case of such occurrences.. Comparing past and present Japanese, Laotian, and Thai populations in 2007 showed fluctuations in the level of antibody titers over the years leading to the belief that modifiable environmental factors can contribute to the prevalence of high titer. In Thailand, the IgM anti-A and anti-B titers were low and were similar to the Japanese titers reported in 2001, but the IgG anti-A and anti-B titers were high and similar to the Japanese titers were reported in1986. A high isoagglutinin titer in the Asian and Black populations has been attributed to mosquito bites and parasitic intestinal infections.
We attempted to study region-wise variations in titers from donors hailing from different Tamil Nadu and Puducherry districts in the present study. Geographical location is known to influence the antibody titers either because of the entomological milieu, prevailing infections, both parasitic and bacterial, which can depend on climatic conditions like humidity, rainfall, etc., in those areas. Donors were analyzed region wise into Pondicherry, Cuddalore, Villupuram, Tiruvannamalai, and various locations. A meaningful association between these locations and high titers could not be arrived at probably because the donor population hailing from these locations is more homogenous than expected. All of them belong to roughly the same cultural and environmental background and hence have comparable habits. The districts mentioned above are closely placed on the map and share a similar culture, including food, language, genetics, and environment.
The limitation of this study was that it is a hospital-based study; hence, there is a possibility of bias in the prevalence results. The sample size from individual geographic subcategories was not sufficiently powered to detect minor differences in the prevalence of titers.
| Conclusion|| |
To conclude, the prevalence of ABO in and around Puducherry is comparable to those published from other regions from Southern India, with the “O” group being the most common. The distribution of antibody titers for anti-A and anti-B is similar to other studies in India, with no significant locoregional variation in our study population. Studies on larger samples with broader representation from the areas with geographical differences may be attempted.
Financial support and sponsorship
This study was intramurally funded by JIPMER.
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]
[Table 1], [Table 2], [Table 3], [Table 4]