<prompt> The blood cell most likely to be involved in phagocytosing bacteria at sites of infection is the leukocyte which in blood smears:Is the smallestIs the least frequently observedHas the greatest number of nuclear lobesHas a bilobed nucleus and eosinophilic granules  <response>: The white blood cellleukocytewith the largest number of lobes in its nucleus is the neutrophil also called the polymorphonuclear leukocyte. Mature neutrophils have a minimum of 3 lobes to their nucleus. These cells are specialized for phagocytosis and killing of bacteria and hence this is the correct answer for this question. Ref: Barrett K.E., Barman S.M., Boitano S., Brooks H.L. 2012. Chapter 31. Blood as a Circulatory Fluid the Dynamics of Blood Lymph Flow. In K.E. Barrett, S.M. Barman, S. Boitano, H.L. Brooks Eds, Ganongs Review of Medical Physiology, 24e. 