Sentence:  Microscopically , both kidneys showed many small cortical scars in which there was glomerular and interstitial fibrosis , tubular atrophy , and an infiltration of <WSD>lymphocytes</WSD> and plasma cells . 
Meaning of the word marked with <WSD> tags:  an agranulocytic leukocyte that normally makes up a quarter of the white blood cell count but increases in the presence of infection