Immune interplay between sepsis and haematological malignancies

Abstract Haematological malignancies (HMs) are characterized by profound immune dysregulation, which increases susceptibility to sepsis. This dysregulation arises from the underlying disease and may be exacerbated by treatments. Sepsis itself induces a biphasic immune response, with an initial hyperinflammatory phase followed by prolonged immunosuppression that can persist for months or years, potentially impacting the course of HMs. This review examines the reciprocal interactions between HMs and sepsis, focusing on innate and adaptive immune alterations, the influence of malignancy-associated dysbiosis, and insights gained from experimental models. In addition, we discuss how sepsis-induced systemic inflammation may influence the progression of the underlying malignancy, through pro-inflammatory cytokine signaling and alterations in the bone marrow microenvironment. Understanding these complex interactions may provide a framework for mitigating infection-related complications and for exploring their influence on the natural history and progression of HM.