Using Slice Pipe with variable parameters in *ngFor

Using the Angular2 pipe slice I can do something like this to only show the first five elements of my items.

<ion-item *ngFor='let item of items | slice:0:5">

How can I use variables instead of hardcoding 0 and 5? I want to do something like this and define start and end in my *.ts file.

<ion-item *ngFor='let item of items | slice:"start":"end"'>