CD19 and lung disorder: The circulating proportion of non-class switched marginal zone (CD19+IgM+CD27+CD23−) and class-switched mature (CD19+IgM−) B-cells was significantly lower in ATB-patients compared to other lung diseases, suggesting that Mtb-infection suppresses and/or exhausts B-cell effector functions, comparable to what has been observed in HIV-positive people (135).