Infections
Abnormal plasma cells do not protect the body from infections. As mentioned before, normal plasma cells produce antibodies that attack germs. For example, if you developed pneumonia, normal plasma cells would produce antibodies aimed at the specific bacteria that were causing the illness. These antibodies help the body attack and kill the bacteria. In multiple myeloma, the myeloma cells crowd out the normal plasma cells, so that antibodies to fight the infection can’t be made. The antibody made by the myeloma cells does not help fight infections. That’s because the myeloma cells are just many copies of the same plasma cell – all making copies of the same exact (or monoclonal) antibody.