IL-9 Is a Biomarker of BIA-ALCL Detected Rapidly by Lateral Flow Assay

Background. A delayed seroma around breast implants is the most common clinical presentation of breast implant–associated anaplastic large cell lymphoma (BIA-ALCL). Interleukin-9 (IL-9), IL-10, and IL-13 concentrations are significantly higher in BIA-ALCL than in benign seromas, offering a means to distinguish between these conditions. Objectives. The aim of this research was to test the ability of a lateral flow assay (LFA) to detect high concentrations of IL-9 rapidly. In addition, the authors compared CD30 and IL-9 LFAs for distinguishing BIA-ALCL from benign seromas. Methods. Samples of 26 seromas (15 benign, 11 malignant) were tested on in-house-prepared LFA strips for IL-9 and CD30. Nanoparticle-conjugated antibodies specific to IL-9 and CD30 were used for detection. The intensity of both the test line (TL) and a control line (CL) were analyzed and the TL/CL ratio was calculated. IL-9 protein and IL-9 transcription factor PU.1 were stained in BIA-ALCL lines and clinical samples. Results. The IL-9 LFA could reliably distinguish BIA-ALCL from benign seromas when the IL-9 concentration was >10 ng/ml. The CD30 LFA was positive in all 11 malignant cases. In 1 case with only faint CD30 and IL-10 TLs, the IL-9 LFA was clearly positive. Immunohistochemistry showed that IL-9 and PU.1 were present in tumor cells in BIA-ALCL lines and clinical samples. Conclusions. Concentrations of IL-9 >10 ng/ml reliably distinguished BIA-ALCL from benign seromas. Moreover, the IL-9 LFA could detect BIA-ALCL when both the CD30 and IL-10 LFAs were not definitive, suggesting a multiplex LFA measuring IL-9, CD30, and IL-10 might be more effective in detecting BIA-ALCL in selected cases.