This notion is further supported by the repeated observations that commensal bacteria are often highly coated with IgA (Palm et al., 2014; Scheithauer et al., 2021; Vitari et al., 2024; Huus et al., 2020), and that beneficial commensal bacteria have decreased IgA binding during malnutrition (Kau et al., 2015). This evidence concerns the gene CD79A and nutritional deficiency disease.