Question

___________________, produced by stem cells found in bone marrow , manufacture antibodies used to counter the effects of antigens

Answer 1

White Blood Cells produce the antibodies. These attach to the antigens and pretty much give us what we call immunity. 

Answer 2

White Blood Cells (WBC), produced by the stem cells found in the bone marrow, manufacture antibodies used to counter the effects of the antigens.

The White Blood Cells are known to provide immunity to the body against foreign bodies like bacteria, virus, proteins, etc. The lymphocyte cells, namely, the B-cells and T-cells are the two key cells that make antibodies for various antigens and kill or lyse the foreign body by recognising the antibiotic marker attach to them.