Immunology: USMLE Q No. 13

[Cardiac Arrest]

A 12-year-old boy returns from summer camp with linear vesicular lesions on his legs. The lesions cause intense itching, but they are not accompanied by fever. The rash spreads over the next few days, but it eventually resolves with the use of a topical over-the-counter medication. Which cells are primarily involved in the development of this type of rash?

A. Keratinocytes
B. Keratocytes
C. Langerhans cells
D. Melanocytes
E. Merkel cells

[H@SSOOM]

C. Langerhans cells


I hope I am wrong because I know nothing in Immunology


If my answer is right , I am lucky

[Cardiac Arrest]

Option C (Langerhans cells) is correct. The patient’s clinical manifestations are consistent with the diagnosis of contact dermatitis resulting from poison ivy (Rhus). This is an example of a type IV hypersensitivity reaction. Langerhans cells are a type of antigen-presenting cell (CD1 positive) located exclusively in the stratum spinosum of the epidermis. They contain Birbeck granules in the cytosol. These cells play a central role in the pathogenesis of contact dermatitis. Specifically, they recognize and transfer molecules from the surface of the skin to T cells located in the neighboring dermis. T cells migrate to nearby lymph nodes, where they proliferate to produce a clone of cells. The clones migrate from the lymph nodes to the original area of poison ivy contact, where they release cytokines, causing the vesicular lesions.

Option A (Keratinocytes) is incorrect. Keratinocytes are cells that synthesize keratin, a substance that protects the skin from abrasions. Keratin is not involved in the pathogenesis of the rash in poison ivy.

Option B (Keratocytes) is incorrect. Keratocytes are special fibroblasts that are located in the substantia propria of the cornea.

Option D (Melanocytes) is incorrect. Melanocytes are cells that synthesize and secrete melanin granules. These granules protect underlying skin tissues from UV light. They have no role in the pathogenesis of the rash of poison ivy.

Option E (Merkel cells) is incorrect. Merkel cells are mechanoreceptors in the skin (particularly the fingertips) and are not involved in the development of contact dermatitis

[MagicOPromotion]

I apologise, but, in my opinion, you are not right. Let's discuss.