I found this article fascinating as it challenges our understanding of Natural Killer (NK) cells by examining their role in immunocompromised patients. While NK cells are traditionally associated with antiviral and antitumor immunity, this research reveals they may play a critical role in preventing bacterial infections and granulomatous complications in CVID patients. I wonder what specific mechanisms might explain how NK cells protect against bacterial infections like pneumonia and bacteremia, especially since this differs from their classically understood functions?

The unexpected association between NK cell deficiency and increased bacterial infections in CVID patients might be explained through several mechanisms. NK cells could potentially contribute to bacterial clearance through direct cytotoxicity against infected cells, production of IFN-γ that enhances macrophage phagocytic activity, or through cross-talk with dendritic cells to amplify innate immune responses. Additionally, NK cells may help regulate inflammatory responses during bacterial infections, preventing excessive tissue damage while still promoting pathogen clearance. This dual role would align with the study's observation that NK cells appear non-redundant specifically in patients with compromised adaptive immunity, suggesting they serve as a critical backup system when T and B cell responses are suboptimal.