CD4 and Opportunistic infection: Bendamustine, a chemotherapy agent with both alkylating and purine analog properties, enhances the effects of anti-CD20 antibodies, leading to prolonged lymphopenia, especially CD4 + depletion, raising susceptibility to opportunistic infections (Lalic et al. 2022; Fung et al. 2019; Saito et al. 2015; Isono et al. 2016; Saburi et al. 2023; Pezzullo et al. 2021).