TitleImmunophenotypic characterization and clinical outcome in cats with lymphocytosis.
Publication TypeJournal Article
Year of Publication2020
AuthorsRout, ED, Labadie, JD, Curran, KM, Yoshimoto, JA, Avery, AC, Avery, PR
JournalJ Vet Intern Med
Date Published2020 Jan
KeywordsAnimals, B-Lymphocyte Subsets, Cat Diseases, Cats, Female, Flow Cytometry, Lymphocytosis, Male, Retrospective Studies, T-Lymphocyte Subsets

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.

Alternate JournalJ Vet Intern Med
PubMed ID31693230
PubMed Central IDPMC6979106
Grant ListK05 CA152715 / CA / NCI NIH HHS / United States
T32 CA094880 / CA / NCI NIH HHS / United States
D08FE-008 / / Morris Animal Foundation /