Step 1: Understand the question.
We must find which cells HIV attacks soon after it enters the body.
Step 2: Recall how HIV enters.
HIV usually enters through body fluids. Once inside, it does not float around freely for long. It needs to enter certain immune cells to spread.
Step 3: Find the first target.
After infection, HIV first enters dendritic cells. These are immune cells that normally catch invaders and show them to other defence cells.
Step 4: See what happens next.
The dendritic cells then carry HIV and present it to helper T cells, which is how the virus reaches and destroys the main immune cells later.
Step 5: Remove the other choices.
Kupffer cells sit in the liver, B-cells make antibodies, and mast cells deal with allergy. None of these is the first cell HIV targets after infection.
Step 6: State the answer.
So the cells attacked first are the dendritic cells.
\[ \boxed{\text{Dendritic cells}} \]