3.4 Perforin levels were decreased in
cytotoxic T
cells
To investigate the ability of cytotoxic lymphocytes to clear
virus-infected cells, we analyzed the expression of one of the major
cytotoxic effector molecules, perforin, in cytotoxic lymphocyte
populations, CD8αα+ and CD8αβ+ αβ T
cells, and effector γδ T cells (Figure 5).
In contrast to all other investigated tissues, perforin expression in
CD8αα+ T cells was increased 7 dpi in blood and spleen
of domestic pigs (Figure 5A, B).
Strikingly, it was reduced 4 dpi and virtually undetectable 5 dpi in the
liver and ghLN of domestic pigs (Figure 5C, D). In wild boar, perforin
expression decreased 5 dpi in the blood, but was elevated above control
levels 7 and 10 dpi in blood, spleen, liver, and ghLN (Figure 5A-D).
CD8αβ+ T cells showed a similar but more pronounced
course with a significantly decreased expression of perforin 4 and 5 dpi
in domestic pigs as well as wild boar in all investigated tissues
(Figure 5A-D). Compared to the perforin expression in uninfected
controls, the perforin loss in CD8αβ+ T cells was even
more distinct than in CD8αα+ T cells. Perforin
expression was back to control levels 7 dpi in all animals. In domestic
pigs, another significant decrease of perforin occurred 10 dpi. This
second reduction was less pronounced in wild boar.
CD8α+ effector γδ T cells showed a perforin expression
comparable to CD8αα+ T cells. In domestic pigs, the
perforin expression was increased 7 dpi in the blood (Figure 5A) but
remained virtually unchanged in the spleen (Figure 5B). Wild boar showed
a reduced perforin expression 5 dpi in blood and spleen. However, this
effect was less pronounced as for the other T-cell populations and
returned to control levels 7 and 10 dpi (Figure 5A, B). In the liver and
ghLN, we detected slight perforin decreases in ghLN 10 dpi but no other
significant expression changes in wild boar (Figure 5C, D). In contrast,
perforin expression in domestic pigs showed a significant decrease 5 dpi
in the liver, and 4 and 5 dpi in ghLN. After the cells regained their
perforin expression levels 7 dpi, there was another loss 10 dpi (Figure
5C, D).