CD8A and colorectal carcinoma: These macrophages secrete IL-10 and inhibit the cytotoxic function of CD8+ T cells.151 Additionally, researchers have found that GABA can bind to GABAA receptors on CD8+ T lymphocytes, suppressing antitumor immunity and promoting tumor growth.151 In non-small cell lung cancer (NSCLC) and CRC, aberrantly expressed glutamate decarboxylase 1 reprograms glutamine metabolism for GABA synthesis.