Dear Student, 1) The substance that produces an immune response in the human body by stimulating lymphocytes (Type of WBC's) is known as antigen. 2) The substance that is produced in response to antigen by WBC's to protect body from these antigens is known as Antibody. Antibodies are generally proteinaceous in nature.3)The drugs or medicines that are synthesised in factories to kill bacteria and hence stop infection being caused by them are known as antibiotics. The word antibiotic means "against life". Regards