The clonal selection theory explains how antigens differ from antibodies. An antigen presenting cell that stimulates virgin T cells is a type of B cell. Cells of the immune system that share the same parent cell are referred to as clones. Lymphocytes that directly destroy body cells already infected by viruses or parasitic fungi are effector cytotoxic T cells. Macrophages produce interleukins, proteins that can signal the brain to raise the body's temperature.
Macrophages can engulf and consume foreign proteins that enter the body.
Macrophages are a type of lymphocyte. Macrophages process antigen and display it on their surface in the form of MHC-antigen complexes. The immune system of vertebrates consists primarily of lymphocytes, and the organs that house them. Antigen primes these cells for division by binding to their antigen receptors, but by itself cannot stimulate cell division. You are the first investigator to demonstrate that cockroaches have antibodies in their circulatory system.