Secreted antibody is required for pulmonary dysfunction in animals with cGVHD. (A) B10.BR mice were transplanted with BM ± splenocytes from WT or (m+s)IgMxJhD BALB/c mice and anesthetized at day 60 after transplantation for PFTs. Resistance, compliance, and elastance were measured; n = 8. (B) Collagen deposition was quantified from trichrome-stained samples as a ratio of blue area to total area of tissue. Quantification was performed with the analysis tool in Photoshop CS3. (C) Infiltration of CD4⁺ cells in the lung and liver of transplanted mice. (D) Lung and liver tissues were harvested, and 6-μm frozen sections were stained with FITC-conjugated anti-mouse Ig for antibody deposition within the tissues. White arrows denote areas of Ig deposition. Representative image from 2 independent experiments; n = 8. *P < .05; **P < .01; ***P < .005.