passages.id: split_5_test_3473_passage
passages.type: progene_text
passages.text: By double - staining with Z27 and DX9 , an antibody specific for 3DL1 , we obtained evidence that in 3DS1 / 3DL1 heterozygous donors significant numbers of NK cells express 3DS1 without co - expressing 3DL1 and that NK cells expressing both alleles are difficult to detect .