( It ( ( affects ( ( the ( white ( blood cells ) ) ) ( known ( as leukocytes ) ) ) ) . ) )
(ROOT (S (NP (PRP It)) (VP (VBZ affects) (NP (NP (DT the) (JJ white) (NN blood) (NNS cells)) (VP (VBN known) (PP (IN as) (NP (NNS leukocytes)))))) (. .)))
It affects the white blood cells known as leukocytes.
(ROOT (S (NP (JJ Leukocytes) (NN blood) (NNS cells)) (VP (VBP are) (ADJP (JJ white))) (. .)))