Three proposed models of the possible fate of LAM molecules released from systemic or urinary
organisms. A. Systemically released LAM is bound to an antibody to form an immune complex within the circulation that impedes renal filtration of LAM across the intact glomerular membrane. This model gives rise to a negative LAM test in the absence of Mtb. B. Circulating LAM unattached to a specific anti-LAM antibody is freely filtered through the kidney into the urine, which gives rise to a positive LAM test in the absence of Mtb. C. Mtb within in the renal tract releases LAM directly into urine, which gives rise to a positive LAM test in the presence of Mtb.