The blood cell most likely to be involved in phagocytosing bacteria at sites of infection is the leukocyte which in blood smears:
The white blood cell(leukocyte)with 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), Ganong's Review of Medical Physiology, 24e.
Is the smallest
Is the least frequently observed
Has the greatest number of nuclear lobes
Has a bilobed nucleus and eosinophilic granules