D-amino acids (which include D-glutamine/glutamate) also have direct immune effects including inhibiting beta-defensin production of epithelial cells (that may alter the host-response to bacteria),91 as well as modulating IgA (through regulation of plasma cell numbers in the gut92 and regulation of symbiotic bacteria that promote B cell diversification and IgA-class switching).92 IgA bound to bacterial surfaces may limit their detection by immune cells in IBD individuals (known as immune-exclusion) to reduce an inflammatory, pathogen-driven immune response against microbiota. Here, CD79A is linked to inflammatory bowel disease.