Tracking Cytotoxic T-cell degranulation in diverse cholesterol conditions

Abstract

Adaptive immunity is vital for surveillance and protection against internal and external threats. It is also essential for pathogen clearance and maintaining immune homeostasis in organisms. CD8+ cytotoxic T-cells (CTLs) are central players in adaptive immunity. They can kill infected/cancerous cells by forming specific and directional immunological synapses with them and releasing cytotoxic granules at the synaptic interface. Although this has been established in previous studies, the precise molecular machinery involved in the delivery and the release of the granules at the synapse remains unclear. Additionally, cholesterol seemingly plays a critical role in CTL activation and effector response, but its functional pathways are yet to be brought to light. We address both these questions by modulating the membrane cholesterol levels of CTLs with the help of pharmacological inhibitors such as MβCD and U-Drug and look at the extent of degranulation in response to these treatments under various activation conditions. This analysis reveals that while the aforementioned drugs demonstrably influence the intracellular movement of granules, they don’t significantly impact the degranulation process. This implies that the two processes are decoupled to a large extent and thus can be regulated independently.