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Multiplexed Fluorescent Immunohistochemical Staining, Imaging, and Analysis in Histological Samples of Lymphoma
Published on: January 9, 2019
Immunophenotypic characterization and clinical outcome in cats with lymphocytosis
Emily D Rout1, Julia D Labadie1, Kaitlin M Curran2
1Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado.
Insights
In cats, neoplastic CD4+ T-cell lymphocytosis is common and has a better prognosis than other aberrant T-cell types. Heterogeneous and B-cell lymphocyte expansions often indicate non-neoplastic conditions.
Area of Science:
- Veterinary Medicine
- Immunology
- Oncology
Background:
- Lymphocytosis is common in cats, but detailed characterization of lymphocyte populations and their clinical outcomes is limited.
- Understanding the immunophenotypic profiles of lymphocytosis is crucial for accurate diagnosis and prognosis in feline patients.
Purpose of the Study:
- To characterize lymphocyte expansions in a large feline population with lymphocytosis.
- To assess the clinical presentation and outcomes associated with different immunophenotypic categories.
- To test the hypothesis that non-neoplastic lymphocytosis is frequent and that neoplastic immunophenotypes have variable prognoses.
Main Methods:
- Retrospective study analyzing blood samples from three cohorts of cats (>1 year old) with lymphocytosis (>6000/μL).
- Immunophenotypic categorization using flow cytometry (n=146).
- Evaluation of clinical data, treatment, and survival information from medical records (n=94) and prevalence of immunophenotypes (n=350).
Main Results:
- Five major immunophenotypic categories were identified: B cell, heterogeneous, CD4+ T cell, CD4-CD8- (double negative) T cell, and CD5-low T cell.
- B-cell and heterogeneous phenotypes were associated with non-neoplastic processes, polyclonal gene rearrangements, younger age, lower lymphocyte counts, and longer survival.
- Neoplastic phenotypes (CD4+ T cell, double negative T cell, CD5-low T cell) had distinct median survival times (752, 271, and 27.5 days, respectively). CD4+ T-cell lymphocytosis was the most common type.
Conclusions:
- Neoplastic CD4+ T-cell lymphocytosis is a common diagnosis in cats, exhibiting a more prolonged clinical course than other aberrant T-cell phenotypes.
- Heterogeneous and B-cell lymphocyte expansions in cats frequently indicate non-neoplastic conditions.
- Immunophenotyping is essential for differentiating neoplastic from non-neoplastic lymphocytosis and predicting outcomes in cats.
Background:
Lymphocytosis is relatively common in cats, but few studies describe lymphocyte populations or the clinical course associated with different immunophenotypic expansions.
Hypothesis/Objectives:
We hypothesized that cats frequently develop non-neoplastic lymphocytosis and that different neoplastic immunophenotypes have variable prognoses. We aimed to characterize the lymphocyte expansions in a large population of cats with lymphocytosis and to assess clinical presentation and outcome in a subset.
Animals:
Three cohorts of cats older than 1 year with lymphocytosis (>6000/μL) were examined to define immunophenotypic categories (n = 146), evaluate outcome (n = 94), and determine prevalence of immunophenotypes (n = 350).
Methods:
Retrospective study of cats with blood submitted for flow cytometry. Medical records (n = 94) were reviewed for clinical data, treatment, and survival information.
Results:
Five major immunophenotypic categories were identified: B cell, heterogeneous (≥2 lineages expanded), CD4+ T cell, CD4-CD8- (double negative [DN]) T cell, and CD5-low-expressing T cell. B-cell and heterogeneous phenotypes were more consistent with a non-neoplastic process, having polyclonal antigen receptor gene rearrangements, younger age at presentation, lower lymphocyte counts, and prolonged survival. The neoplastic phenotypes, CD4+ T cell, DN T cell, and CD5 low T cell, had different median survival times (752 days [n = 37], 271 days [n = 7], 27.5 days [n = 12], respectively). Among CD4+ T-cell cases, cats with abdominal lymphadenopathy, intestinal involvement, or both and females had shorter survival. Among 350 cats with lymphocytosis, CD4+ T-cell lymphocytosis was most common, followed by heterogeneous and B-cell phenotypes.
Conclusions And Clinical Importance:
Neoplastic CD4+ T-cell lymphocytosis is common in cats and has a prolonged clinical course compared to aberrant T-cell phenotypes. Cats with heterogeneous and B-cell lymphocyte expansions commonly have non-neoplastic disease.
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