Figure 4. Histopathology sections from lungs of Patient 1.

(A) H&E section showing fulminant diffuse alveolar damage (DAD), arrows indicate pulmonary oedema (i) and hyaline membrane formation (ii). (B) High magnification of an area of inflammatory infiltrate showing predominantly lymphocytes (iii) and macrophages (iv). (C)-(H) – Immunohistochemistry staining of lungs showing: (C) occasional CD20 (B cell) staining (v); (D) control showing B cells in a lung section from a patient with rheumatoid nodule (positive cells in dark brown); (E) CD56 (NK cell) staining in Patient 1 showed no positive cells compared to positive control (F) from lung of a patient with non-small cell carcinoma; (G) shows CD68 (macrophage) staining (vi) in Patient 1 compared to lung section from the patient with rheumatoid nodule (H). Negative controls (no primary mAb) for (C)-(J) were all negative. All magnifications are ×100, apart from (A) × 20 and (B) and (C) ×200.