14624
METHODS : The percentage of CD4 ( + ) CD28 ( - ) T lymphocyte subsets from peripheral blood mononuclear cells ( PBMCs ) and the expression of PD - 1 / PD - L1 on lymphocytes were analyzed by immunostaining and flow cytometry , respectively .
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Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
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