Minimal Change Disease means there is inflammation in your kidneys. As long as your kidneys are damaged, they can not play their role in retaining the useful substances, thus protein leaks into the urine. With severe damage occurs in kidneys over time, more protein will flow and result in severe proteinuria.
antibody + an antigen = an immune complex
These immune complexes are normally eliminated while still in the circulatory system, but in MN they they accumulate in glomerular basement membrane. The inflamed membrane does not work normally and allows large amounts of protein through the barrier and into the urine (proteinuria) causing signs and symptoms known as Nephrotic Syndrome. MN is one of the most common causes of Nephrotic Syndrome.