How to add a Command to a Tkinter Checkbutton Widget that was populated many times using a the keys of a Dictionary

Question

I have populated a Tkinter Frame with many Checkbuttons (around 100) using the keys from a Dictionary, so I used a for loop to do this. To save the state (0 or 1), I have another dictionary to take care of this. However, when I try to assign a command that will print the state when checked (i.e. clicked on), nothing happens. Here is my code to create the Checkbuttons:

import Tkinter as tk

items = {'Books': 5, 'Games': 20, 'Food': 10, 'Clothes': 2}
items_check = {}

class Application(tk.Frame):
    def __init__(self, master):
        self.master = master
        tk.Frame.__init__(self, master, width=500, height=500)
        self.master.title('Application')
        self.pack_propagate(0)
        self.pack()

        global items
        global items_check
        self.row_var = 0
        self.column_var = 0
        self.row_count = 0
        for key in items.iterkeys():
            items_check[key] = tk.IntVar()
            item_button = tk.Checkbutton(self, text=key, variable=items_check[key], command=self.check_item(key))
            if self.row_count % 15 == 0:
                self.row_count = 0
                self.row_var = 0
                self.column_var += 1
            item_button.grid(row=self.row_var, column=self.column_var, sticky=tk.W)
            self.row_var += 1
            self.row_count += 1

    def check_item(self, key):
        global items_check
        if items_check[key].get() == 1:
            items_check[key].set(0)
            print key
            print items_check[key].get()
        elif items_check[key].get() == 0:
            items_check[key].set(1)
            print key
            print items_check[key].get()

app = Application(tk.Tk())
app.run()

Essentially when I click on any of the checkbuttons, I want to print that specific checkbutton's key and value to the console. Nothing happens with this code. Any ideas? Thanks!