In the immune response process, the cells in charge of the notification to Lymphocytes about the presence of a new antigen are called:
The correct answer and explanation is:
Correct Answer: Antigen-presenting cells (APCs)
Antigen-presenting cells are crucial in the initiation of the immune response. They serve as a bridge between the innate and adaptive immune systems. The primary role of APCs is to detect, capture, and process foreign substances, known as antigens. After processing the antigen, these cells display small fragments of it on their surface using molecules called major histocompatibility complex (MHC) proteins. This process is known as antigen presentation.
The main types of antigen-presenting cells include dendritic cells, macrophages, and B cells. Among them, dendritic cells are the most efficient and specialized for initiating the immune response. When a pathogen enters the body, dendritic cells located in tissues such as the skin or mucous membranes engulf the invader. They then migrate to the lymph nodes where many lymphocytes, including T cells, are located. Here, they present the processed antigen to the T cells through MHC class II molecules.
This presentation acts as a notification to the lymphocytes that a foreign antigen is present in the body. The T cells recognize the antigen-MHC complex using their T cell receptors (TCRs). Once recognition occurs, the T cells become activated. This activation is a critical step in launching a specific adaptive immune response. Helper T cells, in turn, stimulate B cells to produce antibodies or cytotoxic T cells to kill infected cells.
In summary, antigen-presenting cells are essential messengers in the immune system. They alert lymphocytes to new threats by presenting antigens in a form that T cells can recognize, thereby initiating a targeted and effective immune response.