Skin Prick Tests with Solutions of Acid Anhydrides in Acetone

Abstract

Various low molecular acid anhydrides can act as haptens and induce type I allergies. Immunoglobulin E can be detected by radioallergosorbent test (RAST) with the protein conjugates of the respective anhydrides, which are commercially available for some substances. Being almost nonsoluble in water, these species cannot be applied in a skin prick test as a water solution. We will introduce a practicable skin prick test using acetonic solutions of the haptens. 136 persons were tested with acetone for negative control and histamine for positive control. Tests were carried out with 1 and 5% acetonic solutions of phthalic anhydride (PA). The RASTs with conjugates of the PA were performed with Ill subjects who had been exposed to acid anhydrides and with 5 people who possibly had been exposed. In 14 cases, when immediate-type allergy was suspected clinically, a test was performed in addition to the respective anhydride used at the workplace. In order to avoid unspecific histamine liberation, we tested 20 volunteer control persons who had not been occupationally exposed to acid anhydrides. In the prick test performed with acetonic PA solutions, 10 of the occupationally exposed subjects, who had also had a positive result in the RAST with protein conjugates of the PA, showed positive skin reactions, and in 2 further cases, in which the skin reaction was positive, the results of the RAST were just below the limit of a positive evaluation. The skin reaction was positive in 4 cases, in spite of a negative RAST result, while the prick test was reported to be negative in 3 cases although the RAST results were considered to be positive. 97 subjects occupationally exposed to acid anhydrides showed no positive RAST for specific IgE against PA conjugates as well as no positive skin prick test. None of the subjects not occupationally exposed had a positive reaction against any solution, and none of the 136 tested persons developed a positive skin reaction to the solvent acetone. Acetone seems to be practicable for the skin prick test. From a toxicological point of view, it is a harmless solvent for acid anhydrides which are almost nonsoluble in water.

Efficacy of measures of hygiene in workers sensitised to acid anhydrides and the influence of selection bias on the results.

“…Additionally a skin prick test was performed with a 5% solution of MTHPA in acetone. 10 The questionnaire asked about work related symptoms-such as eye complaints, rhinitis, cough, and phlegm from the chest, wheeze and tightness in the chest, shortness of breath, and asthma. A titre of specific IgE antibodies in serum samples >0.3% specific binding or a skin prick test reaction >2 mm was regarded as a sign of sensitisation.…”

Phthalic anhydride [MAK Value Documentation, 2009]

“…16 of 116 workers occupationally exposed to anhydrides (predominantly hexahydrophthalic anhydride, no further details on exposure concentration) reacted in the prick test with phthalic anhydride in acetone. Three other workers reacted in a radioallergosorbent test (RAST) without having effects in the prick test (Drexler et al 1993(Drexler et al , 1994. Specific IgE to phthalic anhydride was detected in one patient on haemodialysis, (no details on clinical relevance) (Castiglione et al 1992).…”