Bronchoalveolar lavage cellular patterns in monoclonal antibody-induced lung disease

The increase in the use of monoclonal antibodies (mAB) as a targeted therapy for a variety of diseases has been accompanied by an increase in reports of interstitial lung abnormalities in treated patients.

Bronchoalveolar lavage (BAL) is routinely performed in these patients to rule out infection, so we sought to determine the BAL cellular pattern in individuals with mAB-induced lung disease (mAB-ILD).

We utilized a case-control study design. Among patients treated with mAB, cases were defined as those with otherwise-unexplained interstitial lung abnormalities, which resolved after cessation of treatment, while controls were defined as those with interstitial abnormalities clearly explained by other etiologies.

From 2000 to 2012, we identified 9 cases and 7 controls. The mean age of the cases was 62.6 ± 26 years and 6 were female. The most common radiographic finding was diffuse ground-glass opacities. The most common BAL cellular pattern was mixed inflammation with moderate lymphocytic and mild neutrophilic alveolitis. The cases had a higher mean lymphocyte count than the controls (40.1 ± 32.6 vs. 13.1 ± 25.5, p = 0.008). The rest of the BAL cellular analyses were similar between the 2 groups. The median CD4:CD8 ratio in 7 patients with >15% lymphocytes was 0.9 (0.6-3). There was no significant difference in the CD4:CD8 ratio between the 2 groups.

Mixed inflammation with moderate lymphocytic and mild neutrophilic alveolitis is the most common BAL cellular pattern in patients with mAB-ILD. Such findings may be useful for the early identification of mAB-ILD.