Expression and prognostic implications of CTLA-4 in canine lymphoma 

Abstract

Immune checkpoint molecules have emerged as crucial regulators of antitumor immunity, often exploited by cancer cells to suppress immune responses and promote disease progression. The current study involved 25 spontaneously occurring canine lymphoma cases to evaluate the expression and prognostic value of CTLA-4. Histologically, the cases included diffuse large B-cell lymphoma, Burkitt’s lymphoma, and marginal zone B-cell lymphoma. Twenty-five lymph node tissue samples were subjected to immunohistochemical analysis to qualitatively assess CTLA-4 expression, with 6 cases graded as 1+, 7 as 2+, and 12 as 3+. Real-time PCR analysis of 21 lymph node tissue samples demonstrated variable CTLA-4 expression, with 52.38% of cases showing overexpression. Although statistical analysis using the Kruskal–Wallis test showed no significant differences in CTLA-4 expression among the histological subtypes (P > 0.05), Kaplan–Meier survival analysis revealed a significant reduction in survival time among dogs with CTLA-4 overexpression (P ≤ 0.05). Furthermore, the Mann–Whitney test indicated significantly higher CTLA-4 expression in dogs that had died compared to those that were alive. The findings of this study suggest that CTLA-4 expression is associated with poor prognosis and reduced survival in canine lymphoma, highlighting its potential utility both as a prognostic indicator and as a promising target for immunotherapeutic intervention.