Understanding Hypersensitivity, Autoimmunity, and Immunodeficiency

Hypersensitivity classically refers to a heightened immune reaction that causes a pathological picture resulting in disruption, discomfort, and sometimes sudden death. It has much in common with autoimmunity, where the antigens are unique. Hypersensitivity reactions require that the host has been previously immunologically sensitized, i.e., exposed at least once to the antigens in question. The allergy: an allergic reaction caused by re-exposure to a specific type of antigen (allergen). Exposure may have been by ingestion, injection, or direct contact.

Immunodeficiency is a pathological condition in which the immune system does not fulfill its protective role, leaving the body vulnerable to infection by pathogens. Immunodeficiencies cause increased susceptibility to infection and a higher prevalence of cancer. Immunodeficiencies may be primary (or congenital) and secondary (or acquired). Primary immunodeficiencies manifest, with few exceptions, from childhood and are due to defects that hinder the proper functioning of the immune system. Secondary immunodeficiencies, however, result from external factors such as malnutrition, cancer, or various types of infections. An example of acquired immunodeficiency is the viral infection HIV/AIDS.

AIDS is a disease that affects humans infected by HIV (human immunodeficiency virus). A person has AIDS when their body, due to immunosuppression caused by HIV, is incapable of providing an adequate immune response against infections. This infection is considered incontrovertible. It is important to highlight the difference between being infected with HIV and suffering from AIDS. A person infected with HIV is HIV-positive and develops AIDS when their CD4 T cell levels (the type of cells that the virus attacks) fall below 200 cells per milliliter of blood. HIV is transmitted through body fluids (such as blood, semen, vaginal secretions, and breast milk). Prevention: The only cause of transmission is the exchange of bodily fluids, including blood and genital secretions. HIV cannot be transmitted by breathing, saliva, casual contact by touching, shaking hands, hugging, kissing on the cheek, mutual masturbation, or sharing eating utensils. Theoretically, transmission through mouth-to-mouth kissing is possible if both people have bleeding wounds or blistered gums, but this is highly unlikely, as saliva contains much lower concentrations of the virus than semen and has antiviral properties. Treatment: Currently, there are medicines called antiretrovirals, which inhibit essential enzymes (reverse transcriptase or protease), reducing HIV replication. This slows the disease's progress and opportunistic infections. While AIDS cannot be cured, with continued use of these drugs, it can develop into a chronic illness compatible with a long and nearly normal life. The HIV enzyme, reverse transcriptase, converts RNA to DNA, making it a primary target in antiretroviral treatment.