Role of Lymphoid Organs
Lymphoid organs are integral to the immune response. The
thymus is where T-lymphocytes mature, while B-lymphocytes mature in the
bone marrow. The
lymph nodes and
spleen act as filtering stations where pathogens are trapped and destroyed.
Histological Features of Immune Cells
Immune cells have distinct histological features.
Neutrophils are characterized by their multilobed nuclei and granules, while
eosinophils have bilobed nuclei and red-staining granules.
Basophils contain large, dark-staining granules.
Lymphocytes are small with a large nucleus-to-cytoplasm ratio, and
monocytes have kidney-shaped nuclei.
Cellular and Humoral Immunity
The immune response can be divided into
cell-mediated immunity and
humoral immunity. Cell-mediated immunity involves T-cells attacking infected or cancerous cells, while humoral immunity involves B-cells producing antibodies that neutralize pathogens.
Antigen Presentation
Antigen presentation is a crucial step in the immune response. Dendritic cells and macrophages present antigens to T-cells, initiating an immune response. This process occurs in the lymphoid tissues where these cells interact.
Histological Changes during Inflammation
During
inflammation, histological changes include increased blood flow, capillary dilation, and infiltration of immune cells such as neutrophils and macrophages. These changes help isolate and eliminate the pathogen while initiating tissue repair.
Memory and Immunological Surveillance
The immune system has memory, allowing for a faster and stronger response upon subsequent exposures to the same pathogen. This is due to the presence of
memory cells. Additionally, the immune system constantly surveys the body for abnormal cells, a process known as
immunological surveillance.
Histological Techniques in Studying Immune Response
Histological techniques such as
immunohistochemistry and
flow cytometry are vital in studying the immune response. These techniques allow for the visualization and quantification of specific cell types and markers, providing insights into the mechanisms of immunity.
