Figure 2

Plasma cells are found in close proximity with pulmonary tertiary lymphoid tissues (TLT) that mainly contain naïve B cells. BALB/c mice were exposed to cigarette smoke for 24 weeks and lung sections were stained by immunochemistry for (A) B cells (B220), (C) IgM, (F) IgG, (H) IgA and (J-K) plasma cells (CD138). (B) Tight clusters of B220 expressing B cells. (D) Cells expressing membrane-bound IgM within a pulmonary TLT. (E) IgM-, (G) IgG- and (I) IgA-secreting cell (cytoplasmic staining) found adjacent to pulmonary TLTs. (J) Absence of plasma cells inside pulmonary TLT which are generally found near pulmonary TLT or (K-L) vessels.