Are white blood cells affected by sickle cell trait?

No, they are not.: In sickle cell trait, only the red blood cells carry an anormality. The white blood cells and platelets are not affected.

Indirectly....: Sickle cell disease affects hemoglobin which is only found in red blood cells, however there is emerging evidence that white blood cells play a role in the effects that sickle cell disease has on a patient. Sickle cell disease is also a disease of inflammation, caused by the sickled red blood cells. Hydroxyurea helps patients by increasing fetal hemoglobin and lowering white blood cell numbers.