Flow cytometry-based direct antiglobulin test for suspected feline immune-mediated thrombocytopenia: Assay development and demographic factors associated with direct antiglobulin test positivity
4 affiliations
- 1Department of Veterinary Microbiology, Faculty of Veterinary Science, Chulalongkorn University, Pathumwan, Bangkok, Thailand
- 2Medical Microbiology Interdisciplinary Program, College of Interdisciplinary and Integrative Studies, Chulalongkorn University, Bangkok, Thailand
- 3Veterinary Diagnostic Laboratory (CU VDL), Faculty of Veterinary Science, Chulalongkorn University, Pathumwan, Bangkok, Thailand
- 4CU VET Blood Bank, Small Animal Teaching Hospital, Faculty of Veterinary Science, Chulalongkorn University, Pathumwan, Bangkok, Thailand
Abstract
Objectives:: This study aimed to develop and evaluate an in-house flow cytometry-based direct antiglobulin test (DAT) for detecting IgG-bound platelets in cats and to investigate the prevalence of DAT positivity and associated risk factors among thrombocytopenic cats.
Methods:: Platelets were identified by CD41/61 expression, and platelet-bound IgG was assessed using flow cytometry. A diagnostic cutoff for the percentage of IgG-positive platelets was established using 100 healthy cats and preliminarily evaluated in 50 cats with severe thrombocytopenia (platelet count <20,000/µl) before being applied to the remaining 411 thrombocytopenic cats (platelet count <200,000/µl) to determine the prevalence of DAT positivity and its associations with platelet count, breed, age, and sex.
Results:: Healthy cats showed 0–10% IgG-positive platelets, and a cutoff of >10% was established. Using this cutoff, 105/461 (22.8%) thrombocytopenic cats were classified as DAT positive. DAT-positive cats had significantly lower platelet counts than DAT-negative cats (median 4000/µl; mean 12,562/µl vs 34,000/µl; mean 47,956/µl; P <0.05), and the percentage of IgG-bound platelets was inversely correlated with platelet count (r = −0.38; P = 0.048). No breed association was identified. Cats aged 5 years were more likely to be DAT positive, whereas castrated male cats were less likely to be DAT positive.
Conclusions and relevance:: Flow cytometry-based DAT is a useful adjunctive diagnostic tool for assessing suspected immune-mediated platelet destruction in thrombocytopenic cats. Younger cats may be at increased risk, whereas castrated male cats may be at lower risk. However, the interpretation of a DAT-positive test result should be made alongside assessment of clinical findings and investigations for underlying causes of thrombocytopenia.
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BibTeX
@article{nedumpun2026flow,
title = {{Flow cytometry-based direct antiglobulin test for suspected feline immune-mediated thrombocytopenia: Assay development and demographic factors associated with direct antiglobulin test positivity}},
author = {Teerawut Nedumpun and Ousakorn Kamenkit and Sinittha Thongwandi and Thitima Tripipat and Suwarath Wadeerat and Supanat Boonyapisitsopa and Napawan Bunpapong},
journal = {Journal of Feline Medicine and Surgery},
year = {2026},
month = aug,
doi = {10.1177/1098612x261478821},
url = {https://doi.org/10.1177/1098612x261478821},
note = {CC BY-NC 4.0},
}
RIS
TY - JOUR
TI - Flow cytometry-based direct antiglobulin test for suspected feline immune-mediated thrombocytopenia: Assay development and demographic factors associated with direct antiglobulin test positivity
AU - Teerawut Nedumpun
AU - Ousakorn Kamenkit
AU - Sinittha Thongwandi
AU - Thitima Tripipat
AU - Suwarath Wadeerat
AU - Supanat Boonyapisitsopa
AU - Napawan Bunpapong
PY - 2026
DA - 2026/08/09
JO - Journal of Feline Medicine and Surgery
DO - 10.1177/1098612x261478821
UR - https://doi.org/10.1177/1098612x261478821
AB - Objectives:: This study aimed to develop and evaluate an in-house flow cytometry-based direct antiglobulin test (DAT) for detecting IgG-bound platelets in cats and to investigate the prevalence of DAT positivity and associated risk factors among thrombocytopenic cats. Methods:: Platelets were identified by CD41/61 expression, and platelet-bound IgG was assessed using flow cytometry. A diagnostic cutoff for the percentage of IgG-positive platelets was established using 100 healthy cats and preliminarily evaluated in 50 cats with severe thrombocytopenia (platelet count <20,000/µl) before being applied to the remaining 411 thrombocytopenic cats (platelet count <200,000/µl) to determine the prevalence of DAT positivity and its associations with platelet count, breed, age, and sex. Results:: Healthy cats showed 0–10% IgG-positive platelets, and a cutoff of >10% was established. Using this cutoff, 105/461 (22.8%) thrombocytopenic cats were classified as DAT positive. DAT-positive cats had significantly lower platelet counts than DAT-negative cats (median 4000/µl; mean 12,562/µl vs 34,000/µl; mean 47,956/µl; P <0.05), and the percentage of IgG-bound platelets was inversely correlated with platelet count (r = −0.38; P = 0.048). No breed association was identified. Cats aged 5 years were more likely to be DAT positive, whereas castrated male cats were less likely to be DAT positive. Conclusions and relevance:: Flow cytometry-based DAT is a useful adjunctive diagnostic tool for assessing suspected immune-mediated platelet destruction in thrombocytopenic cats. Younger cats may be at increased risk, whereas castrated male cats may be at lower risk. However, the interpretation of a DAT-positive test result should be made alongside assessment of clinical findings and investigations for underlying causes of thrombocytopenia.
SN - 1098-612X
SN - 1532-2750
ER -