Table 2.

Peptide-specific T Cell Frequencies Enumerated by IFN-γ ELISPOT and Corresponding Precursor Frequencies by LDA for Influenza Epitopes in a Series of Individuals

Donor		Epitope tested		HLA class I restriction		Sequence		Effector frequency in PBMCs by ELISPOT		Precursor frequency in PBMCs by LDA
WB (9/96)*		M1 58–66		HLA-A2.01		GILGFVFTL		1/15,000		1/100,000
WB (11/96)‡		M1 58–66		HLA-A2.01		GILGFVFTL		1/111,000		1/250,000
SM‡		M1 58–66		HLA-A2.01		GILGFVFTL		1/6,000		1/59,000
JM		M1 58–66		HLA-A2.01		GILGFVFTL		1/77,000		1/333,000
PM		NP 380–388		HLA-B8		ELRSRYWAI		1/43,000		1/200,000
AH		NP 265–273		HLA-A3		ILRGSVAHK		1/45,000		1/42,000

LDAs were performed as described in Materials and Methods and assayed at 14 d of culture, except where marked. Wells were scored positive if peptide-specific lysis was >10% above background. Spontaneous release was <30% of maximal release for all assays, except WB (11/96) (= 40%).  

^* 8 d LDA.  

^‡ 18 d LDA after second restimulation on day 14.