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The mysterious power of cellular immunity: How does it work independently of antibodies?
In the immune system, cellular immunity plays an indispensable role. Although antibodies are often considered the workhorses of immune responses, the workings of cellular immunity is another area worthy of further exploration. Cellular immunity, or cell-mediated immunity, mainly refers to the response produced by T cells and various types of immune cells in the immune system after activation. These responses often protect the body by directly attacking or destroying foreign pathogens without relying on antibodies.
Cellular immunity is supported by a variety of specialized cells, which together provide excellent protection against external threats.
The history of cellular immunity
As early as the end of the 19th century, the medical community had preliminary ideas about the operation of the immune system. The concept at that time was divided into two parts: one was humoral immunity, and the other was cellular immunity. Humoral immunity mainly relies on extracellular humor and antibodies, while cellular immunity focuses on the role of cells. With the advancement of science and technology, scientists have gradually discovered that the role of cellular immunity in fighting diseases is far beyond imagination, especially in the process of fighting pathogens such as viruses and cancer.
The development process of cells
In the human body, all immune-related cells develop from common lymphoid precursors. These lymphoid precursors further differentiate into different types of T cells and natural killer cells. When these immature cells encounter an antigen, they are activated and transform into attack-capable effector T cells. This process is crucial because only when T cells are exposed to a specific pathogen can they achieve a true immune response.
The operation of cellular immunity can use specific cells to launch a fierce counterattack against infected cells, effectively targeting internal and external pathogens.
The operating mechanism of cellular immunity
Cellular immunity mainly relies on two categories of T cells: CD4+ helper T cells and CD8+ cytotoxic T cells. CD4+ cells assist the functions of other immune cells by secreting cytokines, while CD8+ cells can directly kill infected or abnormal cells. This direct intervention method makes cellular immunity outstanding in resisting viruses, bacteria and tumors.
Diversity of cellular immunity
According to different stimulation signals, CD4+ helper T cells can be further classified into TH1 cells, TH2 cells and TH17 cells. The secretions of these cells have different effects on the immune response. For example, TH1 cells focus on activating macrophages, while TH2 cells stimulate B cells to produce antibodies. Cellular immunity also exhibits a high degree of flexibility and adaptability in the face of different pathogens.
Cellular immunity is not a single entity. It is composed of multiple cell types that work together to achieve defense tasks.
The relationship between disease and cellular immunity
In addition to its role in fighting infections, cellular immunity is also closely related to many autoimmune diseases. For example, autoimmune diseases such as rheumatoid arthritis and multiple sclerosis can be seen as the result of dysregulated cellular immune responses. In these diseases, cellular immunity is overactivated and attacks autologous tissues, leading to inflammation and damage.
Future research directions
Currently, the scientific community is still deepening its understanding of cellular immunity, and researchers hope to further develop new treatments through cellular immunity. For example, the use of CAR-T cell therapy to modify a patient's own T cells to attack cancer cells has shown good clinical results. With the advancement of gene editing technology, more targeted cell therapies may be created in the future, allowing the immune system to fight various pathogens more efficiently.
The operating model of cellular immunity allows us to rethink the diversity and complexity of immune responses. When we understand the unique roles of different cells in immune defense, can we respond to disease challenges more effectively?
