White Blood Cells White cells are the body's defence against bacterial attack. Invading bacteria release chemicals into the blood. The white cells adheres to the bacterium and begins to produce vesicles. The vesicles move towards the suit of adhesion and pseudopodia begin to engulf the bacterium. The vesicles contain enzymes. The enzymes-filled vesicles fuse with the vacuole surrounding the bacterium. The product of digestion are absorbed by the white cell.