The Immune System
The Innate Immune System
A Very Important Part
When discussing the immune system, it is also very important to mention the lymphatic system, which is a special part of white blood cells, and also contains lymph nodes (3). There are two specific kinds of lymphocytes known as B and T cells, and they are important in the function of adaptive immunity. Macrophages, dendritic cells, and B-cells in the cortical region make contact with the antigens and process them for presentation to B-cells and T- cells, thereby initiating an immune response (3). Antigens are proteins that are found on the surface of the pathogen (4). When an antigen enters the body, the immune system produces antibodies against it. Lymphocytes are then able to recognize the antigen and produce antibodies (which destroy the pathogen) (4). As a result, B-cells are stimulated to develop into antibody-secreting plasma cells, and T-cells are stimulated to develop into effector T cells of various classes (3). Antibodies leave the lymph node by the efferent ducts that empty into the blood stream (3).
The Backup Plan: The Adaptive Immune System
Innate immunity, by itself, may not be sufficient in protecting a host against an invading pathogen or preventing disease from occurring (6). This is where the secondary response called adaptive immunity comes into play. The adaptive immune system is antigen-specific and reacts only with the substance that induced the response (6). The adaptive immune system exhibits immunological memory. It "remembers" that it has encountered an invading substance (antigen) and reacts more rapidly on subsequent exposure to the same organism (6).
Adaptive immunity is activated when T-cells, which are stimulated by dendritic cells, are active and recognize foreign antigens. Dendritic cells have a special feature on their surface called the major histocompatibility complex (MHC), which presents the foreign antigen to the T cell through a process called pathogenesis (7). These responses include direct attack of antigen-bearing cells by cytotoxic T lymphocytes, stimulation of B cells to produce antibodies against the antigens, and induction of inflammation, along with enhanced innate responses in the area where the antigen is present (7). This complex system can be better understood in the following video.
Cool Animation of the Way the Innate and Adaptive
Immune Systems Work Together (10)