Acute Hypersensitivity Reactions, GDD and NSF a brief comparison of Immune Reactions
In many respects GDD is much easier to understand than NSF, as it essentially follows the pattern of an allergic reaction, except that it is cell-based and not principally antibody based. Acute hypersensitivity reaction (AHR) is as straightforward as GDD, it is primarily direct Mast cell activation.
Example: a number of people have an allergic reaction to peanuts, much rarer is an allergic reaction to walnuts, same true comparing strawberries and blueberries. A major difference is Gd is retained, so the allergen remains with you constantly. Simple obvious comparison. Essentially any chemical/ polypeptide/protein we come into physical contact with (breathing, eating, touch, and entry into the tissues: iv/ im/ subcutaneous) can in principle generate
an immune reaction. In many respects it is amazing that our immune system is able to control immune reactions as well as it does, considering how many contacts are constantly made. So like a peanut or bee sting, it should be no surprise that some people can be allergic to a GBCA. So T cell immune reaction, which is my opinion of what GDD is, should come as no surprise. Also no surprise that some GBCAs are more allergenic than other.s. Ir appears that Prohance may be lower on the allergic scale for GDD than other agents. AHR and GDD not infrequently occur together... This does make one think that early reports on MRI with GBCAs that describe failure of conventional steroid and antihistamine treatment for AHR, maybe they also had combined AHR/GDD, and that is why short term treatment failed - but as happens in Radiology, and other fields, these patients were not followed up.
NSF arises due to dissociation of the Gd and ligand of the GBCA and renal failure .. not so clear cut. For example what magical unique property does renal failure confer to result in NSF - is it just retaining more Gd? For a number of people, retaining more of something administered iv can occur without kidney failure. This greater propensity to dissociation appears to also primarily activate late immune reaction, which is activation of the bone marrow cell infiltrates, best known cd 34+ circulating fibrocytes. This is much more complex than a bee sting, a peanut reaction, AHR and GDD.
The types of immune reactions, promoting factors, and mitigating factors are all critical to the understanding of toxicity of GBCAs, and their successful treatment and hopefully avoidance..