Humoral
It is called the adaptive defense and consists of antibodies and lymphocytes, often called the humoral response.
T helper cells
The part of the immune response that is specific to a particular pathogen is the adaptive immune response. This response involves the activation of lymphocytes, particularly T cells and B cells, which recognize specific antigens presented by the pathogen. B cells produce antibodies that target these antigens, while T cells can directly kill infected cells or help orchestrate the immune response. This specificity allows for a tailored and effective defense against distinct pathogens.
Two specific defenses are the humoral immune response and the cell-mediated immune response. The humoral immune response involves B cells producing antibodies that target specific pathogens in the blood and extracellular fluid, neutralizing them or marking them for destruction. In contrast, the cell-mediated immune response involves T cells, particularly cytotoxic T cells, which directly attack and destroy infected or cancerous cells, as well as helper T cells that activate other immune cells. Both responses are crucial for the adaptive immune system's ability to recognize and remember specific pathogens.
The adaptive immune response can specifically tailor its response to a particular antigen through the activation and proliferation of lymphocytes, particularly T cells and B cells. Upon encountering an antigen, these cells undergo clonal selection and expansion, producing specific receptors that bind to that antigen. This specificity allows for a targeted and efficient immune response, including the production of antibodies by B cells and the activation of cytotoxic T cells. Additionally, the adaptive immune system retains memory cells, enabling faster and more robust responses to subsequent exposures to the same antigen.
Memory cells are long-lived cells that "remember" specific pathogens and help mount a faster and stronger immune response upon re-exposure. Effector cells, on the other hand, are specialized cells that actively participate in the immune response by directly eliminating pathogens. Memory cells are part of the adaptive immune system, while effector cells can be part of both the innate and adaptive immune responses.
If a pathogen crosses the second line of defense, which includes innate immune responses like inflammation and phagocytosis, the body activates the adaptive immune system. This involves the activation of lymphocytes, such as T cells and B cells, which specifically target and eliminate the pathogen. The adaptive response also generates memory cells, providing long-lasting immunity against future infections by the same pathogen. If the adaptive immune response fails, the infection can progress and potentially lead to illness.
Helper T cells
Dendritic cells and macrophages play crucial roles in the immune response within lymph nodes. Dendritic cells act as antigen-presenting cells, capturing and processing antigens from pathogens and then presenting them to T cells to initiate an adaptive immune response. Macrophages help in phagocytosing pathogens and debris, while also presenting antigens to T cells, thereby facilitating the activation and differentiation of these immune cells. Together, they orchestrate the immune response by enhancing communication and coordination between innate and adaptive immune systems.
Regional lymph nodes where they present to T cells, activating the adaptive immune response.
Cytotoxic T cells play a crucial role in the adaptive immune response by identifying and destroying infected or abnormal cells in the body. They recognize specific antigens on these target cells and release toxic substances to kill them, helping to eliminate the threat and prevent further infection.
The third line of defense against pathogens in the body is called the adaptive immune response. This response involves the activation of specific lymphocytes, such as T cells and B cells, which recognize and target specific pathogens. Unlike the innate immune response, the adaptive response develops memory for previously encountered pathogens, allowing for a faster and more effective response upon re-exposure. This system is crucial for long-term immunity and protection against various diseases.