Table 1. Modeling of IFN-γ producing cytotoxic CD8+ T cells (CD8+ IFN-γ+ T cells) as a function of IL-2 producing CD4+ helper T cells (CD4+ IL-2+ T cells) and time (model 1 and model 2) in the rAd5-rAd5 group, HVTN 068 trial.

Models	CD4+ IL2+ Tcell (each time)		CD4+ IL2+ Tcell (day 0—day 7)		CD4+ IL2+ Tcell (day 14)		Time (splines)	AIC
	β	p-value	β	p-value	β	p-value	p-value
Model 1	0.004	0.28	-	-	-	-	<0.01	-846.2
Model 2	-	-	-0.001	0.82	0.031	<0.01	<0.01	-860.7

Model 1: % of CD8+ IFN- modelled as a function of % of CD4+ IL-2+ response at each time, adjusted for time (splines).

Model 2: % of CD8+ IFN- modelled as a function of % of CD4+ IL-2+ response introduced as two explanatory variables (one taking values of observed % of CD4+ IL-2+ before week 2 and the second taking two values: 0 before week 2, and then the value observed at week 2 at each visit until the end of the follow-up), adjusted for time (splines)

The shown regression coefficients (β) correspond to the estimated increase in % of CD8+ IFN-γ+ T cells per 0.1% increase in CD4+ IL-2+. For an increase of 0.10% in the percentage of CD4+ IL-2+ at week 2, the percentage of CD8+ IFN-γ increased of 0.03% throughout follow-up (p<0.01). In contrast, the values of CD4+ IL-2+ before week 2 were not significantly associated with CD8+ IFN-γ+ response (p = 0.82).