People who are allergic to cats are actually allergic to certain proteins found in the animals' skin secretions and saliva; which particular proteins are responsible, however, varies from allergy sufferer to allergy sufferer. Since all cats shed skin and spread saliva around their environment, there is no such thing as a cat incapable of provoking allergic reactions, although it is common for a given cat to cause an allergic reaction in some -- but not all -- people who are allergic to cats.
The statement 'Any particular individual will be allergic to some breeds of cat but not to others' is most strongly supported by the information above.