Table 2. T cell and cytokine profiles of unimpaired and impaired elders.

Unimpaired			Impaired
Ranked factor #a	T cellb or humoral parameter	CEV (%)c	Ranked factor #a	T cellb or humoral parameter	CEV (%)c
1	CD56+CD28null cell frequency, and CD56-MFI/GMFI in all subsets	15.3	1	CD158a+ cell frequency, and CD158e-MFI/GMFI in all subsets	26.3
2	NKG2D+ cell frequency, and NKG2D-MFI/GMFI in all subsets	54.4	2	CD28null cell frequency in CD8 T cells only	45.2
3	CD56+CD57+CD28null cell frequency, CD56-MFI/GMFI, and CD57-MFI/GMFI in CD4 T cells only	58.7	3	NKG2A+ cell frequency, and NKG2A-GMFI in all subsets	58.5
4	CD16+ cell frequency, and CD16-MFI/GMFI in all subsets	63.1	4	Co-existing Th1 (IFN-γ, TNF-α) and Th2 (IL-6)	64.0
5	CD56+CD57+CD28null cell frequency, CD56-MFI/GMFI, and CD57-MFI/GMFI in CD8 T cells only	69.8	5	CD158e+ cell frequency, and CD158e-MFI/GMFI in CD8 T cells only	73.2
6	Co-existing Th1 (IL-12p70), and Th2 (IL-5, IL-13)	75.3	6	NKG2A+ cell frequency, and NKG2A-GMFI in CD8 T cells	76.3

^aListed are the top six factors that emerged from Factor (or Principal Component) Analysis with Varimax rotation and Kaiser normalization. The analysis was performed by parsing T cell and humoral parameters with a level of significance at an Eigen value (EV) = 5.0 or greater. Covariates entered in the analysis were age, gender, and body mass index. From 112 immune parameters (see text) entered into the analysis, those with rotated loading coefficient of at least 0.70 in absolute value were considered as those identifying the factor (principal component).

^bT cell subsets, i.e. CD4, CD8, and DN, were defined by the frequency cells lacking CD28 and/or expressing CD16, CD56, CD57, CD158a, CD158e, NKG2A, and NKG2D, and as well as by the actual level of expression of each of the latter seven antigens (expressed as MFI and GFMI; see Materials and Methods).

^cCumulative Eigen value; 75% CEV was used as a quantitative cut off to define the composite T cell-humoral profile of the groups.