It consists of tissues, cells, soluble molecules like antibodies and lymphoid organs. The WBC cells called the leucocytes have a significant role as they seek out to destroy the disease-causing organisms. These leucocytes are stored in different locations in the body including the spleen, bone marrow, and thymus. These organs are called as the lymphoid organs. The leucocytes are also present in the lymph nodes of the body.It is considered as the main lymphoid orga and. It produces all the blood cells including the lymphocytes. The thymus is an organ that is present near to the heart, beneath the breastbone.