SS-A (Ro) and SS-B (LA) antibodies found in Sjogren syndrome are targeted against:
**Core Concept**
The question is testing the student's understanding of the autoantibodies associated with Sjogren syndrome, a chronic autoimmune disorder characterized by exocrine gland dysfunction, particularly affecting the salivary and lacrimal glands. SS-A (Ro) and SS-B (La) antibodies are specific autoantibodies found in patients with Sjogren syndrome.
**Why the Correct Answer is Right**
SS-A (Ro) and SS-B (La) antibodies are targeted against the Ro and La ribonucleoprotein (RNP) complexes, which are present in the cytoplasm of various cells, including epithelial cells and lymphocytes. These antibodies are a hallmark of Sjogren syndrome and are often used as diagnostic markers for the disease. The presence of these antibodies is associated with the activation of immune cells and the production of pro-inflammatory cytokines, leading to the destruction of exocrine glands.
**Why Each Wrong Option is Incorrect**
* **Option A:** Incorrect because SS-A (Ro) and SS-B (La) antibodies are not targeted against the nuclear antigens, such as histones or DNA.
* **Option B:** Incorrect because these antibodies are not specific to Sjogren syndrome and can be found in other autoimmune disorders, such as systemic lupus erythematosus (SLE).
* **Option D:** Incorrect because SS-A (Ro) and SS-B (La) antibodies are not targeted against the cell surface antigens, such as CD23 or CD40.
**Clinical Pearl / High-Yield Fact**
The presence of SS-A (Ro) and SS-B (La) antibodies in a patient's serum can be a useful diagnostic clue for Sjogren syndrome, particularly in patients with symptoms of dry mouth and dry eyes. These antibodies are often associated with a more severe disease course and a higher risk of developing other autoimmune disorders.
**Correct Answer: C. Ro and La ribonucleoprotein (RNP) complexes.**