Subject: What is the real mechanism for penicillin allergy?

In all immunology textbooks I have read not one mentions about how a T helper cell specific for carrier determinants is activated to 
help B cell specific for haptenic (penicillin) determinant to differentiate into antibody secreting 
plasma cells. I understand that T helper cells should be tolerant to the self carrier proteins. 
Hence, there should be no help from T helper cell for penicillin-specific B cells. 

Re: What is the real mechanism for penicillin allergy?