Where are most of the White Blood Cells in human blood?

Although White Blood Cells (also called Leukocytes) can be found in the bloodstream, only about 1-2% of those are present at that given time. Most White Blood Cells are waiting within lymphatic tissues and lymphoid organs - such as the spleen, lymph nodes, and bone marrow. When needed, they are able to quickly reach the infected or damaged tissues through the lymphatic system.