Relationship between the percentage of LT occupied by collagen and two parameters: baseline LT CD4+ T cell population and change in peripheral CD4+ T cell count after 6 months. (a) Size of the baseline LT CD4+ T cell population is compared with the percent area of the TZ occupied by collagen. There is a significant correlation between these values (R2 = 0.72, P < 0.0001, Spearman rank correlation). (b) Change in the peripheral CD4+ T cell population after 6 months of HAART is compared with the percent area of the TZ occupied by collagen. There is significant correlation between these measurements (R2 = 0.91, P < 0.001).