Basophils are the rarest of WBCs, averaging only 0.5-1% of the leukocyte population. Their cytoplasm contains large, coarse, histamine-containing granules that have an affinity for the basic dyes and stain purplish-black.eukocytes, or white blood cells (WBCs), are the only formed elements that are complete cells, with nuclei and the usual organelles. Accounting for less than 1% of total blood volume, leukocytes are far less numerous than red blood cells.