Induces apoptosis of host cells (PubMed:25242740). Is immunogenic with highly specific seroreactivity towards TB patients' serum (PubMed:27751956). Strongly interacts with EsxK to form a heterodimeric complex under reducing conditions. The complex is regulated by the redox state of EsxL. Probably secreted via the ESX-5 / type VII secretion system (T7SS) (Probable). Secretion may depend on complex formation with EsxK (Probable). Differentially expressed under different growth conditions. Highly expressed in sputum bacteria. EsxKL deletion mutant shows reduced intracellular growth in primary human macrophages. Also shows growth defects in the absence of host cells. In BALB/c mice, immunization with EsxL-FIA induces a pro-inflammatory response with elevated levels of TNF and IL-6, along with low induction of IFN-gamma, IL-2 and IL-10, but no induction of IL-4. Belongs to the WXG100 family. ESAT-6 subfamily.