An allergen is a type of antigen that produces an abnormally vigorous immune response in which the immune system fights off a perceived threat that would otherwise be harmless to the body.Such reactions are called allergies.hen an allergen enters the body of an individual that is predisposed to allergies, it triggers an immune reaction and the production of antibodies. These allergen antibodies migrate to mast cells lining the nose, eyes and lungs.
Progestins are synthetic progestogens, medications that have effects similar to those of progesterone. The two most common uses of progestins are for hormonal contraception (either alone or with an estrogen), and to prevent endometrial hyperplasia from unopposed estrogen in hormone replacement therapy.
Progesterone is a female sex hormone produced mainly in the ovaries following ovulation each month. Itâs a crucial part of the menstrual cycle and maintenance of pregnancy. Progesterone helps to regulate your cycle, but its main job is to get your uterus ready for pregnancy. After you ovulate each month, progesterone helps thicken the lining of the uterus in preparation for a fertilized egg. If there is no fertilized egg, progesterone levels drop again and menstruation begins.