Rosette formation with sheep RBC’s indicate functioning of –
**Core Concept**
The rosette formation test is a laboratory technique used to assess the presence and function of certain receptors on the surface of immune cells, particularly T cells and natural killer (NK) cells. This phenomenon is based on the interaction between the Fc portion of immunoglobulins and the Fc receptors present on the surface of these immune cells.
**Why the Correct Answer is Right**
The correct answer is related to the Fc receptors, which are responsible for the rosette formation around sheep red blood cells (SRBCs) that have been coated with antibodies. The process involves the binding of the Fc portion of these antibodies to the Fc receptors on the surface of T cells and NK cells, leading to the formation of a rosette-like structure around the SRBCs. This interaction is crucial for the recognition and destruction of foreign cells by the immune system.
**Why Each Wrong Option is Incorrect**
* **Option A:** This is not a relevant option in this context, as the rosette formation test is not directly related to the function of complement system.
* **Option B:** While the complement system does play a role in immune responses, it is not directly involved in the rosette formation test.
* **Option C:** This option is incorrect because the rosette formation test is not a measure of phagocytic activity, but rather a measure of the presence and function of Fc receptors on immune cells.
**Clinical Pearl / High-Yield Fact**
The rosette formation test is a useful tool for identifying and characterizing T cells and NK cells, which play critical roles in cell-mediated immunity.
**Correct Answer: D. Fc receptors. Functioning Fc receptors.**