The specific source used varies by niche, with lactoferrin dominating in the nasopharynx and also in cerebrospinal fluid during meningitis (lactoferrin crosses the blood-brain barrier during inflammation), and transferrin and hemoglobin dominating in the bloodstream (Criado et al., 1993; Perkins-Balding et al., 2004; Cornelissen and Hollander, 2011a; Neumann et al., 2017). The gene discussed is LTF; the disease is infectious meningitis.