♦️Host-tumor interactions are complex interactions between tumor cells and the host immune system that influence tumor progression, metastasis, and immune evasion.
♦️Studies have shown that tumors often use various mechanisms to evade immune surveillance, thereby creating a microenvironment that supports their survival and proliferation.
🔹Mechanism 1: Immune surveillance and evasion
Initially, the immune system recognizes and eliminates transformed cells through mechanisms such as cytotoxic T lymphocytes (CTLs), natural killer (NK) cells, and macrophages. However, tumors develop strategies to evade immune detection. They downregulate major histocompatibility complex (MHC) molecules to prevent antigen presentation to T cells. In addition, tumors secrete immunosuppressive factors such as transforming growth factor-ẞ (TGF-β) and interleukin 10 (IL-10) to suppress immune responses.
🔹Mechanism 2: Tumor microenvironment (TME)
The TME plays a key role in immune evasion. It includes cancer cells, stromal cells, and infiltrating immune cells. Tumors recruit regulatory T cells (Tregs) and myeloid suppressor cells (MDSCs), which inhibit antitumor immunity. In addition, they induce metabolic changes such as hypoxia and lactate accumulation, which further inhibit immune cell function.
🔹Mechanism 3: Immune checkpoint molecules
Tumors utilize immune checkpoints such as programmed death-1 (PD-1) and cytotoxic T lymphocyte-associated protein-4 (CTLA-4) to inhibit T cell activation. Cancers use these pathways to evade immune destruction.
🔹Mechanism 4: Host response and therapeutic intervention
The host’s immune system constantly adapts to the tumor, forming a dynamic balance. Immunotherapies, such as immune checkpoint inhibitors and adoptive T cell therapies (e.g., CAR-T cells), aim to restore anti-tumor immunity. However, challenges such as immune-related adverse events and drug resistance require further investigation.
🔹Therefore, understanding host-tumor interactions is essential for designing effective therapies to overcome immune evasion and achieve durable tumor control.
