In sickle cell anemia, why there is increase susceptibility of infection despite elevated wbc ?

Functional Asplenia: The spleen, which is part of the immune system, tends to stop working by the time a baby with sickle cell disease is 4-6 months of age due to damage done by the sickled red blood cells. The spleen's function is to act as a filter to remove bacteria from the blood. Once the spleen is no longer working, the individual is at risk for developing certain types of serious bacterial infections.