Raji cell assay are used to quantitate –
**Core Concept**
The Raji cell assay is a laboratory test used to quantitate the level of immune complexes in a patient's serum. It is based on the principle of complement-mediated lysis of Raji cells, which are a type of B lymphoblastoid cell line. The **complement system** plays a crucial role in this assay.
**Why the Correct Answer is Right**
Although the answer options are not provided, the Raji cell assay is typically used to detect and quantitate **immune complexes**. The mechanism involves the binding of immune complexes to the surface of Raji cells, which activates the **complement system**, leading to cell lysis. The degree of cell lysis is directly proportional to the amount of immune complexes present in the serum.
**Why Each Wrong Option is Incorrect**
**Option A:** Without the specific option, it's challenging to provide a detailed explanation. However, if Option A refers to a different laboratory test or parameter, it would be incorrect because the Raji cell assay is specific for immune complexes.
**Option B:** Similarly, if Option B refers to an unrelated parameter, it would be incorrect due to the specific application of the Raji cell assay.
**Option C:** This option would also be incorrect if it does not relate to immune complexes or the complement system.
**Option D:** Without the specific details, it's difficult to provide a precise explanation, but if it's unrelated to immune complexes, it would be incorrect.
**Clinical Pearl / High-Yield Fact**
The Raji cell assay is a valuable tool for diagnosing and monitoring autoimmune diseases, such as **Systemic Lupus Erythematosus (SLE)**, where immune complexes play a significant role in the pathogenesis. Remembering the association between the Raji cell assay and immune complexes is crucial for interpreting laboratory results.
**Correct Answer:** D. Immune complexes