CD79A and chronic obstructive pulmonary disease: In distal airways, IgA+ B cells numbers were increased in lymphoid follicles (LF) from severe COPD compared to control non-smokers [26] and the intra-LF IgA+ cells (%) were further increased in severe COPD compared to mild disease [26], presumably representing an adaptive immune response to microbial and/or self-antigens, particularly in severe disease [26].