Resident Ontario Veterinary College Guelph, Ontario, Canada
Abstract:
Background: The pathophysiology of feline immune-mediated cytopenia (IMC) remains unclear. Identifying pathogenic mechanisms could lead to more targeted treatment.
Objective: To describe lymphocyte subpopulations of cats with IMC at diagnosis and after immunosuppressant treatment. Animals: Eight cats diagnosed with IMC and treated with immunosuppressants.
Methods: Prospective pilot study. Lymphocytes were analyzed by flow cytometry at diagnosis and 7, 30, and 60 days after starting immunosuppressants. Bone marrow cytology and histopathology samples were assessed at diagnosis. Complete blood count and treatment were recorded at each timepoint.
Results: Median absolute lymphocyte, CD5+, CD8+, and MHCII positive cell counts were lower on Day 60 (lymphocyte: 5600/μL, IQR 3685 - 8265; CD5+: 1382/μL, IQR 730 - 2317; CD8+: 849/μL, IQR 644 - 1162; MHCII: 1830/μL, IQR 449 - 2528) compared to Day 7 (lymphocyte: 960/μL, IQR 415 - 2035; CD5+: 190/μL, IQR 107 - 433; CD8+: 126/μL, IQR 62 - 280; MHCII: 266/μL, IQR 2.8 - 531; p = 0.022 for each). Hematocrit increased between Day 1 and Day 7 (1: 0.115 L/L, IQR 0.085 - 0.1425 vs 7: 0.26 L/L, IQR 0.185 - 0.31; p = 0.022). Cats without myelofibrosis had higher hematocrit on Day 60 (absent: 0.375 L/L, IQR 0.3675 L/L - 0.3825 L/L vs present: 0.345 L/L, IQR 0.3225 - 0.3525; p = 0.042). Conclusion and clinical importance: Improvement of cytopenia in cats was accompanied by alterations in total lymphocyte count and subsets, including CD5+, CD8+, and MHCII-positive cells after 60 days of immunosuppressants.
