In this study, framed as an exploration of the suitability of the serum IgA assay for the diagnosis of NTM infections, we have shown low sensitivity values when each antigen was evaluated separately, around 30% and up to 50% when considering Mabs-positive CF-patients; but with a doubling in sensitivity when the two antigens were combined, culminating in a value of 60%, specifically for the diagnosis of Mabs infections. Here, CD79A is linked to cystic fibrosis.