Although multiple myeloma originates from cells which are essentially immune cells, those cells are dysfunctional. Cancer cells are like zombies and never perform their main function as healthy cells.
The rapid division of such cells also encroaches upon healthy white blood cells in the bone marrow causing their death and therefore decreased number of white blood cells in the circulation. This leaves the body highly susceptible to infections especially what we call “opportunistic infections” which are infections caused by organisms that are normally weaker than the body’s immunity, so they take the opportunity and infect when the body is vulnerable. Infections also become more severe and can be life-threatening.