Emerging studies shed light on pivotal immunological mechanisms and microbiome interactions affecting disease progression and therapeutic potential. Investigations reveal the gut microbiome’s influence on brain cancer metabolism, the therapeutic promise of IL22RA1 in colon cancer progression, and immune cell-based therapies including microglia replacement in neurodegenerative diseases. Additionally, novel vaccines and diagnostics targeting viruses and parasitic diseases are being developed, while immune checkpoint therapy toxicities and T-cell exhaustion dynamics are being unraveled through multi-omics techniques.