• Fever is a symptom of an anti-infection defense mechanism that appears with body temperature exceeding the normal range due to an increase in the body's temperature.
  
  
• Mechanical barriers — which include the skin, mucous membranes, and fluids such as tears and urine — physically block pathogens from entering the body. Chemical barriers — such as enzymes in sweat, saliva, and semen — kill pathogens on body surfaces.
  
  
• Antibodies or immunoglobin are protective proteins produced by the immune system in response to the presence of a foreign substance, called an antigen. Antibodies recognize and latch onto antigens in order to remove them from the body.
  
  
• The receptors usually recognize components of microorganisms that are not found on cells of the host, e.g. components of bacterial cell wall, bacterial flagella or viral nucleic acids.
  
  
• The thymus is a small gland in the lymphatic system that makes and trains special white blood cells called T-cells. The T-cells help the immune system fight disease and infection. The thymus gland produces most of your T-cells before birth.
  
  
• Phagocytosis is the process by which certain living cells called phagocytes ingest or engulf other cells or particles. It is defensive reaction against infection and invasion of the body by foreign substances (antigens).
  
  
• Inflammation is a protective response involving immune cells, blood vessels, and molecular mediators. The function of inflammation is to eliminate the initial cause of cell injury, clear out damaged cells and tissues, and initiate tissue repair.

receptor, thymus, phagocytosis, inflammation, lymphatic organs, messenger molecules (cytokines, interleukins…), agglutination, peptide, memory cells, immunological memory, B-plasma cells, cytotoxic cells (=cytotoxic T-Lymphocytes), thymus, T helper cells (=CD4 cells), APC (=Antigen presenting cell), phagocytosis, cell clone, clonal selection, somatic recombination, autoimmune disease, Macrophage, precipitation of soluble antigens pairs of terms: innate and specific immune response, self and no self, MHCI/II, humoral and cellular immune response, primary and secondary response, activation phase and effector phase, monoclonal and polyclonal antibodies, antibody and receptor, antibody and antigen, heavy chain and light chain, active and passive immunization, B- and TLymphocytes