Hipesensitivitas tipe 4

Summary

This video discusses Type 4 hypersensitivity, an immune reaction mediated by T lymphocytes (T-helper and cytotoxic T cells) against autoantigens or environmental antigens. The mechanism involves CD4 naïve T cells activated by dendritic cells, leading to tissue damage, potentially causing diseases like Type 1 diabetes, Hashimoto's thyroiditis, and severe skin reactions like Stevens-Johnson syndrome. Diagnostic tests are non-specific, and treatment often involves corticosteroids, such as methylprednisolone, to reduce inflammation, although these drugs carry side effects. The video aims to provide insights into the condition and its clinical manifestations.

Takeaways

• 🙏 Hypersensitivity Type 4 is an excessive immune reaction mediated by T lymphocytes against autoantigens or environmental antigens.
• 🧬 There are two types of T lymphocytes involved in Type 4 hypersensitivity: cytotoxic T cells (Tdx) and helper T cells (CD4+).
• 🦠 Pathogenesis involves naive CD4 T cells being activated by dendritic cells that carry antigens bound to MHC class II molecules.
• 🔗 The T cells bind to the antigen via their T-cell receptors and express CD4 molecules to enhance the binding.
• 🧫 Dendritic cells secrete interleukin-12, allowing naive T cells to develop into mature helper T cells (TH1).
• ⚡ Mature TH1 cells release clinical manifestations, leading to tissue damage and diseases like Type 1 diabetes and Hashimoto's thyroiditis.
• 🌿 Additional symptoms can include conditions like contact dermatitis from poison ivy and drug reactions such as Stevens-Johnson syndrome.
• 🔍 There are no specific diagnostic tests for Type 4 hypersensitivity.
• 💊 Treatment options include corticosteroids like methylprednisolone, which help reduce inflammation but come with significant side effects.
• 🤲 The explanation of Type 4 hypersensitivity aims to raise awareness and provide clarity on this immune response mechanism.

Q & A

What is Type 4 hypersensitivity?

Type 4 hypersensitivity is an excessive immune reaction mediated by T lymphocytes, specifically against autoantigens or environmental antigens.

Which T lymphocytes are involved in Type 4 hypersensitivity?

Two types of T lymphocytes are involved: cytotoxic T cells (T CD8 or T cytotoxic cells) and T-helper cells (T CD4 or T-helper cells).

What is the role of CD4 T cells in the pathogenesis of Type 4 hypersensitivity?

CD4 T cells are activated when naive CD4 T cells bind to an antigen presented by dendritic cells through the MHC class II complex. This activation leads to the release of cytokines and further immune responses, contributing to tissue damage.

How does Type 4 hypersensitivity lead to tissue damage?

Type 4 hypersensitivity causes tissue damage through two mechanisms: activation of CD4 T-helper cells (which release inflammatory cytokines) and cytotoxic T cells that directly kill target cells.

What clinical manifestations can result from Type 4 hypersensitivity?

Clinical manifestations include tissue-specific damage, such as destruction of pancreatic beta cells (leading to Type 1 diabetes) and damage to the thyroid gland (causing Hashimoto's thyroiditis). Other manifestations include contact dermatitis from poison ivy and drug reactions like Stevens-Johnson syndrome.

What diseases are associated with Type 4 hypersensitivity?

Diseases associated with Type 4 hypersensitivity include Type 1 diabetes mellitus, Hashimoto's thyroiditis, contact dermatitis (e.g., poison ivy), and drug reactions like Stevens-Johnson syndrome.

Is there a specific diagnostic test for Type 4 hypersensitivity?

No, there is no specific diagnostic test for Type 4 hypersensitivity.

What treatments are used for Type 4 hypersensitivity?

Treatment options include corticosteroids such as methylprednisolone, which help inhibit inflammation. However, these medications can have many side effects.

How does the activation of naive CD4 T cells occur in Type 4 hypersensitivity?

Naive CD4 T cells are activated when they bind to an antigen presented by dendritic cells through the MHC class II complex. This process is aided by the secretion of interleukin-12, which helps the CD4 T cells differentiate into T-helper 1 (Th1) cells.

What are the side effects of corticosteroid therapy in Type 4 hypersensitivity treatment?

While corticosteroids like methylprednisolone can reduce inflammation, they are associated with multiple side effects, including immune suppression and other systemic effects.