Cw alloimmunization in multitransfused thalassemic patients of North India: Prevalence and approach to transfusion

Sangeeta Pahuja; Shivali Sehgal; Geetika Sharma; Jagdish Chandra; Nupur Parakh; Manisha Singh; Ramvilash Yadav

doi:10.4103/gjtm.gjtm_89_21

ORIGINAL ARTICLE

Year : 2022 | Volume : 7 | Issue : 1 | Page : 51-53

C^w alloimmunization in multitransfused thalassemic patients of North India: Prevalence and approach to transfusion

Sangeeta Pahuja¹, Shivali Sehgal², Geetika Sharma¹, Jagdish Chandra³, Nupur Parakh³, Manisha Singh¹, Ramvilash Yadav¹
¹ Department of Immunohematology and Blood Transfusion, Lady Hardinge Medical College, New Delhi, India
² Department of Pathology, Hamdard Institute of Medical Sciences and Research, New Delhi, India
³ Department of Paediatrics, Lady Hardinge Medical College, New Delhi, India

Date of Submission	27-Sep-2021
Date of Decision	21-Jan-2022
Date of Acceptance	21-Mar-2022
Date of Web Publication	29-Apr-2022

Correspondence Address:
Dr. Shivali Sehgal
Department of Pathology, Hamdard Institute of Medical Sciences and Research, New Delhi
India

Source of Support: None, Conflict of Interest: None

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DOI: 10.4103/gjtm.gjtm_89_21

Abstract

Background and Objectives: The C Willis or C^w antigen is a low-incidence antigen of Rh system. The antibody against the C^w antigen (anti-C^w) is an IgG antibody which may occur naturally or may be immune in nature. The identification of C^w antibody is important since it has the potential to cause hemolytic disease of the newborn as well as hemolytic transfusion reaction. This study was conducted with the aim of determining the prevalence of C^w antibody in multitransfused thalassemic patients enrolled in a Regional Blood Transfusion Center (RBTC) of North India. Methods: A retrospective descriptive observational study was conducted at the Department of Immunohematology and Blood Transfusion, LHMC and Associated Hospitals. All transfusion-dependent thalassemic (TDT) patients and non-TDT (NTDT) patients enrolled in the RBTC of the hospital till December 2018 were included in the study. Antibody screening was performed in all recipients before each transfusion. The prevalence of anti-C^w was estimated. Results: A total of 567 thalassemic patients (including TDT and NTDT) were registered in RBTC, LHMC till December 2018. On pretransfusion antibody screening and identification, 3 out of 567 thalassemic patients were found to have alloimmunization against C^w antigen. The prevalence of anti-C^w in multitransfused thalassemics was 0.53%. Conclusion: The prevalence of anti-C^w is variable in different populations and it is not a very commonly reported antibody in patients with thalassemia. One should be aware of the approach to transfusion in thalassemic patients who develop C^w alloimmunization.

Keywords: C^w alloimmunization, multitransfused, North India, thalassemics

How to cite this article:
Pahuja S, Sehgal S, Sharma G, Chandra J, Parakh N, Singh M, Yadav R. C^w alloimmunization in multitransfused thalassemic patients of North India: Prevalence and approach to transfusion. Glob J Transfus Med 2022;7:51-3

How to cite this URL:
Pahuja S, Sehgal S, Sharma G, Chandra J, Parakh N, Singh M, Yadav R. C^w alloimmunization in multitransfused thalassemic patients of North India: Prevalence and approach to transfusion. Glob J Transfus Med [serial online] 2022 [cited 2022 Jun 26];7:51-3. Available from: https://www.gjtmonline.com/text.asp?2022/7/1/51/344342

Introduction

The Rh blood group system was first brought to light by Levine and Stetson in 1939 when they described hemolytic transfusion reaction (HTR) in an obstetric patient after blood transfusion from her husband.^[1] Today, 61 Rh antigens have been characterized.^[2] The C Willis or C^w antigen is a low-incidence antigen of Rh system (Rh8) which results from single amino acid substitution (Gln41Arg), most often found on the RhCe protein.^[1] The antibody against the C^w antigen (anti-C^w) was first described in 1946.^[3] It may occur naturally or may be immune in nature.^[1] This is an IgG antibody which has the potential to cause hemolytic disease of the newborn (HDN) as well as HTR.

Aims and objective

This study was conducted with the aim of determining the prevalence of C^w antibody in multitransfused thalassemic patients including both transfusion-dependent thalassemic (TDT) as well as nontransfusion dependent thalassemic (NTDT) patients, enrolled in a Regional Blood Transfusion Center (RBTC) of North India.

Materials and Methods

This retrospective descriptive observational study was conducted at the Department of Immunohematology and Blood Transfusion, LHMC and Associated Hospitals. All TDT and NTDT patients enrolled in the RBTC of the hospital till December 2018 were included in the study.

As per the guidelines, antibody screening is done in all recipients before each transfusion. At our institute, screening is performed using Bio-Rad ID-Diacell I-II-III Asia (three-cell panel, Manufacturer: DiaMed GmbH, Switzerland). If positive, antibody identification is done using Bio-Rad ID-DiaPanel (11-cell panel, Manufacturer: DiaMed GmbH, Switzerland) to identify the specificity of the antibody and to assess the clinical significance.

Identification of anti-C^w requires the reagent red blood cells (RBCs) panel which includes C^w antigen-positive RBCs and allows exclusion of other clinically significant alloantibodies in result interpretation. In cases with anti-C^w antibody, antigen profiling of the red cells for C^w antigen was performed using monoclonal anti-C^w serum (Manufacturer: Bio-Rad Medical Diagnostics GmbH, Germany).

Results

A total of 567 thalassemic patients (including TDT and NTDT) were registered in RBTC, LHMC till December 2018. On pretransfusion antibody screening and identification, 3 out of 567 thalassemic patients were found to have alloimmunization against C^w antigen. Thus, the prevalence of anti-C^w antibody in multitransfused thalassemia patients in our center was 0.53% [Table 1].

Table 1: Details of multitransfused thalassemic patients who developed C^w antigen

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Rh and Kell profiles of these patients are shown in [Table 2]. In all three patients, antibody screening by three-cell panel in Coombs phase at 37⁰C revealed positivity in the first cell. On performing, antibody identification by 11-cell panel in Coombs phase at 37⁰C, the first cell was positive. There was no diminution of the reaction with papain. Since only a single cell in the panel had C^w antigen-positive RBCs, confirmation of the presence of anti-C^w was obtained by testing the serum with three different lots of antibody screening or identification panels. On antigen profiling of the red cells of all three patients, C^w antigen was negative.

Table 2: Rh Kell profile of the three multitransfused thalassemic patients who developed C^w antigen

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These patients were thereafter transfused with C^w negative and indirect antiglobulin test (IAT) crossmatch compatible blood. On follow-up after repeated transfusions with C^w negative blood, antibody titers declined and became serologically undetectable in two out of three cases [Table 1]. The third case shows 1 + reaction with C^w positive cells.

Discussion

Anti-C^w was first described by Callender and Race in a multitransfused patient (DCe/DCe) with systemic lupus erythematosus who had been transfused DCe/DCe C^w + red cells.^[4]

Identification of anti-C^w is important because of its potential in causing mild-to-severe HTRs as well as mild-to-moderate HDN.^{[5],[6],[7],[8]} Anti-C^w antibody is an IgG antibody which may be seen in combination with other antibodies to RBCs. In fact, it can be easily missed if it coexists with anti-D.

The C^w, C^x, and MAR antigens are encoded by alleles at the CC locus of the Rh system. C^w and C^x are low-frequency antigens which are antithetical to the high-frequency antigen MAR.^[9] Anti-C^w may show dosage that is, it reacts more strongly with cells from individuals who are homozygous for C^w antigen.^[1] This emphasizes the significance of antibody screening for all patients (particularly multitransfused groups) as it may be missed on crossmatch if antigen is in the heterozygous form.

C^w antigen is a low-prevalence antigen. It is found in about 2% of the Caucsian and is very rare in African-Americans.^[1],[10] The frequency in North Indian donors has been previously reported to be 1.2%.^[11] It varies from 1% in African-Americans to around 9% in Latvians.^[12],[13]

The incidence of anti-C^w is variable in different populations. Bowman et al. reported an incidence of 0.1% of anti-C^w in pregnant females. HDN was reported in 2% of the babies whose mothers had been alloimmunized with anti-C^w.^[14] Jain et al. reported the antibody in a young female in North India.^[11] Bujandric and Grujic described anti-C^w in two patients of chronic renal failure on dialysis.^[3]

The prevalence of anti-C^w in multitransfused thalassemics was 0.53% in our study. Anti-C^w is not a very commonly reported antibody in thalassemic patients. Datta et al. did not come across any C^w alloantibody in their cohort of 500 thalassemic patients from East India.^[15] Similarly, Elhence et al. did not observe any anti-C^w in their study of 280 thalassemic patients of Northern India.^[16] Singer et al. did not find anti-C^w in any of the 64 multitransfused TDT patients of predominantly Asian descent.^[17] Furthermore, Cheng et al. did not report any anti-C^w in 382 Chinese thalassemic major patients.^[18] No anti-C^w was reported by Thompson et al. in their study of 697 thalassemic patients from 28 institutions of North America and the United Kingdom.^[19] However, El-Beshlawy et al. found anti-C^w in 11 out of a total of 200 thalassemic patients in Egypt.^[20] Ethnic differences and homogeneity of population can explain the differences in alloimmunization status in different geographical areas.^[21]

If C^w antigen is not represented in the antibody screening panel, these antibodies can remain undetected. Therefore, alloantibody screening panels should include C^w positive cells since they may not be as infrequent as they are thought to be and can result in clinically significant HDN and HTR.

If anti-C^w is identified during pregnancy, titers and follow-up should be done as per the guidelines to avoid HDN. In addition, physicians must be aware that the occurrence of anti-C^w can lead to serious transfusion complications.

Thalassemic patients who develop anti-C^w should ideally receive C^w negative RBCs after IAT crossmatch. Since C^w is a low-prevalence antigen, C^w antigen-negative blood is readily available.^[1] Even after the antibody becomes undetectable serologically, these patients should continue receiving C^w antigen-negative blood.

C^w antisera are expensive and not readily available in all blood banks. If the patient is known to have C^w antibody and testing with C^w antisera is not feasible, red cells compatible by IAT at 37⁰C can be transfused.^[22],[23]

Providing compatible blood for transfusion in patients with antibodies to low-incidence antigens is not a problem, however, the identification of the same is necessary to assess their potential in causing HDN and HTR. In addition, these antibodies may complicate the detection of other clinically significant antibodies in multitransfused patients.

Conclusion

It is important to be aware of C^w antibody since it can lead to serious transfusion complications or HDN. The C^w antigen should be included in all the antibody screening panels. Furthermore, heterozygous antigen may get missed by crossmatch alone due to the dosage phenomenon. Patients with anti-C^w should be counseled regarding the potential of the antibody to cause HDN and HTR. Ideally, all patients with anti-C^w should be given a bio-passport or an antibody card mentioning the same since they might be negative on repeat testing but may develop a reaction if given C^w positive blood.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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