Change text size of a single textblock from a ListView

I want to change the text size of the first textblock from a listview.

Here is the xaml:

<ListView  Grid.Row="2" BorderBrush="White"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Name="ListView1"
ItemsSource="{Binding Path=Line}"
                   HorizontalAlignment="Stretch"><ListView.ItemTemplate><TextBlock/><DataTemplate><StackPanel>				<TextBlock Text="{Binding Path=aline}"/></StackPanel> </DataTemplate></ListView.ItemTemplate></ListView >

The textblock inside the stackPanel is how I represent the data from the binding. I just want to edit the first textblock and I'm not even sure if this is even possible.