White blood cells protect our boby from external infection like bacterial fungal or viral.
To achieve this altimate goal white blood cells carry out very complex functions like.
1.Secretion of antibodies
2.Creating Memory of infection and disease causing agents cancerous cells for secretion of Antibodies against them and for neutralization of these infections agents and foreign particles cancerous cells.
Viruses, Bacteria and foreigne particles in our body even cancerous cells are killed by white blood cells.
3. Opsonin are protien which attaches then selves, tag , Viruses, Bacteria and foreigne particles in our body even cancerous cells after which these opsonised agents are brought near to white blood cells and then are eliminated by Immunoglobulin attachment to them for neutralization or Engulfing of entire cell by Neutrophils, Basophiles agranulocites.
A fantastic video is available here of how phagocytosis occurrs how white blood cell engulf a living bacteria or virus circulating in our body.
Enjoy watching same and you may ask us questions about immunology in comment section of thisa website.
Here is funtastic video of a cell engulfing bacteria, phagocytosis how a cell execute phagocytosis.