MHC_II is present on .

Options

A. macrophage
B. b-lymphocytes
C. Dendritic cells
D. All of the above

Answer

To answer the question "MHC_II is present on," we will follow these steps:

### Step 1: Understand MHC
MHC stands for Major Histocompatibility Complex, which is a set of proteins that play a crucial role in the immune system. They are involved in the presentation of antigens to T cells.

### Step 2: Identify the Types of MHC
There are two main classes of MHC molecules: MHC Class I and MHC Class II. MHC Class II molecules are primarily found on professional antigen-presenting cells (APCs).

### Step 3: Identify Antigen-Presenting Cells (APCs)
APCs are cells that can present antigens to T cells. The main types of APCs include:
- Dendritic cells
- Macrophages
- B lymphocytes

### Step 4: Determine the Presence of MHC Class II
MHC Class II molecules are specifically expressed on:
- Dendritic cells
- Macrophages
- B lymphocytes

### Step 5: Conclusion
Since MHC Class II is present on all of the mentioned cells (macrophages, B lymphocytes, and dendritic cells), the correct answer is "all of the above."

### Final Answer
MHC_II is present on **all of the above** (macrophages, B-lymphocytes, dendritic cells).

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