WBC stands for white blood cells, also called leukocytes. When white blood cells clump together, or agglutinate, the phenomenon is called leukocyte agglutination. Blood tests are used to detect WBC clumping.

Among the several different types of white blood cells, neutrophils typically are involved in leukocyte agglutination. Neutrophil agglutination can occur in response to an assortment of diseases or conditions.

A less common type of WBC clumping involves lymphocytes, a different type of white blood cell. Lymphocytic agglutination is associated with specific diseases, including non-Hodgkins lymphoma and chronic lymphocytic leukaemia.

The man-made amino acid EDTA, used during chelation therapy to treat cholesterol build-up in blood vessels, can cause WBC clumping.

WBC clumping also can be caused by a cooling temperature within a blood sample.

WBC clumping of any origin can cause blood tests to show a low white blood cell count. Avoiding the WBC clumping caused by temperature changes or other outside influences can help reduce misleading test results and unnecessary follow-up medical procedures or treatments.