Django limiting Foreign Key values based on model field choice

Currently I have two tables, user types and user subtypes, that needs to be related based on condition.
For example.:
The UserType USER_A can only be related to UserSubtypes TYPE_A and TYPE_B entries
The UserType USER_B can only be related to UserSubtypes TYPE_C entries
The UserType USER_C can only be related to UserSubtypes TYPE_D entries

class UserTypes(models.Model):
    USER_TYPES = [
        ("USER_A", "USER_A"),
        ('USER_B', 'USER_B'),
        ('USER_C', 'USER_C'),
    ]
    account_type = models.ForeignKey(UserSubtypes)
    user_type_name = models.CharField(choices=USER_TYPES, default="USER_A")
class UserSubtypes(models.Model):
    USER_SUBTYPES = [
        ("TYPE_A", "TYPE_A"),
        ('TYPE_B', 'TYPE_B'),
        ('TYPE_C', 'TYPE_C'),
        ('TYPE_D', 'TYPE_D'),
    ]
    user_type_name = models.CharField(choices=USER_TYPES)

How can I achieve this kind of conditional relationship?