Laravel 5: Call to Undefined Method Response::header() when trying to access data through API?

I built an API with Laravel and while trying to make a get request via URL localhost8000/api/itemsI built a CORS middleware.

<?php

namespace App\Http\Middleware;

use Closure;

class Cors
{

    public function handle($request, Closure $next)
    {
        return $next($request)
            ->header('Access-Control-Allow-Origin', '*')
            ->header('Access-Control-Allow-Methods', 'GET, POST, PUT, PATCH, DELETE, OPTIONS')
            ->header('Access-Control-Allow-Headers','Content-Type, Authorization, X-XSRF-TOKEN');
    }
}

When trying to access data via API, localhost:8000/api/items, I get the following URL on my Laravel terminal and

Call to undefined method Symfony\Component\HttpFoundation\Response::header()

via Chebli Mohamed