Objetivou-se determinar a imunoexpressão da Caspase-3, Bcl-2 e Bax no linfoma intestinal felino e relacionar com o desfecho clínico-terapêutico dos pacientes. Foram utilizados tecidos oriundos de biopsias intestinais de 30 felinos, admitidos na Clínica Veterinária Vetmasters (São Paulo-SP), com diagnóstico histopatológico de linfoma. Os pacientes foram acompanhados até o momento da cura clínica ou óbito. Os animais foram submetidos ao mesmo protocolo quimioterápico (clorambucil e prednisolona). A avaliação imunoistoquímica foi realizada no LiverLab (Faculdade de Medicina Veterinária e Zootecnia da Universidade de São Paulo). Foram utilizados os seguintes anticorpos: Caspase-3, Bcl-2 e Bax. A determinação da imunoexpressão da Caspase-3, Bcl-2 e Bax foi avaliada de acordo com o percentual de linfócitos neoplásicos positivos. O valor utilizado para considerar o resultado significante foi de 0.05 (p<0.05). Para determinar se houve diferença na imunomarcação da Caspase- 3, Bcl-2, Bax e razão Bcl-2/Bax, utilizou-se o teste de qui-quadrado (X² ). Para verificar se existiam associações entre as respostas terapêuticas (RC remissão completa; RP - remissão parcial; AR - ausência de remissão), tempo de sobrevida e óbito com a imunoexpressão da Caspase-3, Bcl-2, Bax e razão Bcl-2/Bax, utilizou-se o teste exato de Fisher. A análise de sobrevivência foi realizada pelo modelo de Kaplan-Meier. Houve diferença pelo teste de X² (p<0.01) nas probabilidades dos escores de Caspase-3, sendo que a maioria apresentou escore 0. Existiu diferença pelo teste de X² (p<0.01) nas probabilidades dos escores de Bcl-2, onde a maior parte apresentou escore 4. Não houve diferença pelo teste de X² (p= 0.22) para os escores de Bax (0 a 12). Para a razão Bcl-2/Bax, o valor menor que 0.33 representou caso de melhor prognóstico e quando o valor foi igual ou maior a 0.33, considerou-se caso de pior prognóstico. Existiu associação entre o tipo de resposta terapêutica e a imunoexpressão de Caspase-3 pelo teste Exato de Fisher (p = 0.01). A maioria dos animais, com RC, possuiu associação com o escore 0. Ocorreu associação entre o tipo de resposta terapêutica e a imunoexpressão de Bcl-2 pelo teste Exato de Fisher (p= 0.04). A maioria dos animais possuíram RC associada ao escore 4. Não existiu associação entre o tipo de resposta terapêutica e a imunoexpressão de Bax e na razão Bcl-2/Bax, pelo teste Exato de Fisher (p= 0.22 e p= 0.05, respectivamente). Ocorreu associação entre o tempo de sobrevida de até 1 mês e a imunoexpressão de Caspase- 3 (p<0.01). Não houve associação entre o tempo de sobrevida e a imunoexpressão de Bcl-2 (p= 0.83), Bax (p ≥0.05) e razão Bcl-2/Bax (p= 0.92). Não existiu associação entre o óbito e as imunoexpressões de Caspase-3 (p= 0.40), Bcl-2 (p= 0.76), Bax (p= 0.05) e razão Bcl-2/Bax (p= 0.40). Houve imunoexpressão da Caspase-3, Bcl-2 e Bax no linfoma intestinal felino, em diferentes escores, e nem todos se relacionaram com o desfecho clínico-terapêutico dos pacientes. Estudos futuros são necessários para melhor compreensão da imunoexpressão dos fatores pró e antiapoptóticos no linfoma intestinal felino e sua concreta relação com o prognóstico.

The objective was to determine the immunoexpression of Caspase-3, Bcl-2 and Bax in feline intestinal lymphoma and relate it to the clinical and therapeutic outcome of the patients. Tissues from intestinal biopsies of 30 cats, admitted at Vetmasters Veterinary Clinic (São Paulo-SP), with histopathological diagnosis of lymphoma, were used. The patients were followed until clinical cure or death. The animals were submitted to the same chemotherapy protocol (chlorambucil and prednisolone). Immunohistochemical evaluation was performed at LiverLab (Faculty of Veterinary Medicine and Animal Science, University of São Paulo). The following antibodies were used: Caspase-3, Bcl-2 and Bax. The determination of Caspase-3, Bcl-2 and Bax immunoexpression was evaluated according to the percentage of positive neoplastic lymphocytes. The value used to consider the result significant was 0.05 (p <0.05). To determine whether there were differences in the immunolabeling of Caspase-3, Bcl-2, Bax and Bcl-2/Bax ratio, the chi-square (X2) test was used. To check whether there were associations between therapeutic responses (CR - complete remission; PR - partial remission; AR - no remission), survival time and death with the immunoexpression of Caspase-3, Bcl- 2, Bax and Bcl-2/Bax ratio, we used Fisher ’s exact test. Survival analysis was performed by the Kaplan-Meier model. There was a difference by X2 test (p <0.01) in the probabilities of Caspase-3 scores, where most of them had a score of 0. There was a difference by X2 test (p <0.01) in the probabilities of Bcl-2 scores, where most of them had a score of 4. There was no difference by X2 test (p = 0.22) for Bax scores (0 to 12). For the Bcl-2/Bax ratio, a value lower than 0.33 represented a case of better prognosis and when the value was equal or higher than 0.33 it was considered a case of worse prognosis. There was an association between the type of therapeutic response and Caspase-3 immunoexpression by Fisher ’s exact test (p = 0.01). Most animals with CR had an association with score 0. There was an association between the type of therapeutic response and Bcl-2 immunoexpression by Fisher ’s Exact test (p = 0.04). The majority of animals had CR associated with score 4. There was no association between the type of therapeutic response and Bax immunoexpression and Bcl-2/Bax ratio by Fisher ’s Exact test (p= 0.22 and p= 0.05, respectively). There was an association between survival time up to 1 month and Caspase-3 immunoexpression (p <0.01). There was no association between survival time and immunoexpression of Bcl-2 (p= 0.83), Bax (p≥0.05) and Bcl-2/Bax ratio (p= 0.92). There was no association between death and the immunoexpressions of Caspase-3 (p= 0.40), Bcl-2 (p= 0.76), Bax (p= 0.05) and Bcl-2/Bax ratio (p= 0.40). There was immunoexpression of Caspase-3, Bcl-2 and Bax in feline intestinal lymphoma at different scores, and not all were related to the clinical-therapeutic outcome of the patients. Future studies are needed to better understand the immunoexpression of pro-and antiapoptotic factors in feline intestinal lymphoma and their concrete relationship with prognosis.