THE INFLUENCE EXERTED BY CUTANEOUS LIGANDS IN SUBJECTS REACTING TO NICKEL SULFATE ALONE AND IN THOSE REACTING TO MORE TRANSITION-METALS

To study the influence exerted by cutaneous ligands in nickel reaction s we have evaluated the patch tests responses to 4 aqueous nickel salt s (sulfate, chloride, nitrate, acetate) able to form different complex es with different geometry. Two groups of respectively 71 subjects who previously reacted only to nickel sulfate 5% petrolatum (pet) and of 30 subjects who previously reacted to nickel sulfate 5% pet and to at least 1 other transition metal, were simultaneously repatch-tested to 200 mu g of Ni++ contained in nickel sulfate in pet and to 47 mu g of Ni++ contained in 4 different aqueous nickel salts. Another 2 groups o f 25 subjects with the same characteristics were simultaneously repatc h tested to 200 mu g of Ni++ in pet and to 12 mu g of aq Ni++ as in th e first 2 groups. Visual score, total score, and mean value of the rea ctions were utilized in evaluating the degree of the responses. On tes ting to 200 mu g of Ni++ in pet all the subjects were able to give pos itive responses. Whilst a higher percentage of the responses of 2(+) d egrees was found in subjects reacting to nickel sulfate 5% pet alone, a higher percentage of responses of 3(+) degrees was observed in subje cts reacting to more transition metals. On testing to 47 and 12 mu g o f aqueous Ni++ a large variability of responses to the single salts wa s observed in all the subjects. However, in subjects reacting to more metals there were either a greater number of multiple responses to 3 o r 4 salts or responses stronger than those found in subjects reacting to nickel sulfate alone. Although patch testing cannot give us complet e information about the degree of previous exposure, the results arisi ng from the tests seem to demonstrate that the subjects allergic to ni ckel and other transition metals are more reactive than the subjects a llergic only to nickel to the application of the same amounts of Ni+contained in different salts. When considering the QSAR model, the dif ference in the sensitizing potential of the metal at the same penetrat ion properties can depend on the possibility of combining with specifi c ligands. Therefore, it is likely that in subjects reacting to more m etals there is a more uniform availability of cutaneous ligands which conditions the formation of complexes more immunogenic. The arising in flammatory reaction in these cases leads to a stronger but less specif ic response.