Host Defense: Total Picture (Non-Specific Immune response) to specific immune response
White Blood Cells will engulf the bacteria, this happens when the organism is a foreign element to our body

Bacteria is engulfed in a bag, called digestive vacuole

Action 1.
The  Lysosome containing digestive enzymes, fuses with the digestive vacuole and pours its contents in the digestive vacuole. The bacteria inside the digestive vacuole ( at his stage is known as Phagolysosome), get destroyed by the action of the enzymes.
Action 2
These phagocytes also send signals through some soluble products or through physical contacts, to another kind of white cells (T cells) that in turn ask some cells (B Cells) to produce antibodies against the invador.
Signaling through contacts
Signaling through factors