IN-VIVO AND IN-VITRO DIAGNOSIS OF LATEX ALLERGY AT GROOTE-SCHUUR-HOSPITAL

Objective. The aim of this study was to evaluate the diagnostic utilit y of skin-prick tests, radio-allergosorbent tests (CAP RASTs), basophi l histamine release, sulphidoleukotriene release and Western blotting in the diagnosis of latex allergy at Groote Schuur Hospital. Design. P atients with a history suggesting latex hypersensitivity were recruite d via staff health and allergy clinics at Groote Schuur Hospital. A cl inical assessment was followed by laboratory investigation and skin-pr ick testing. A control group consisted of laboratory and hospital staf f who had regular latex exposure but were asymptomatic. Setting. Hospi tal-based cohort at Groote Schuur Hospital. Participants. Twenty-three patients with suspected latex allergy; 10 control subjects exposed to , but not clinically sensitive to, latex. Main outcome. Skin-prick tes ting was more sensitive than in vitro diagnostic tests for the diagnos is of latex allergy. Results. Eighteen of 21 (85.7%) of the patients t ested had a positive skin-prick test with a commercial latex solution (Allerbioprick) and 17/21 (80%) tested skin-prick-positive with an in- house glove extract. GAP RASTs were positive in 13/23 patients (56.5%) , sulphidoleukotriene release was positive in 10/23 (43%), histamine r elease assay was positive in 10/23 (45%) and Western blots were positi ve in 8/23 (34.7%). All patients with only urticaria were Western blot -negative and CAP RAST-negative, suggesting that they have very little circulating latex-specific IgE. Although patients who were Western bl ot-positive tended to have multi-organ involvement, both patients with anaphylaxis were Western blot-negative. Conclusion. Latex allergy is a significant clinical problem at Groote Schuur Hospital. Titrated ski n-prick testing performed in a controlled environment can safely and r eliably confirm the diagnosis in patients who do not give a history of anaphylaxis. The CAP PAST was the most sensitive in vitro test for la tex allergy locally available, but lacks sensitivity in patients prese nting with urticaria only.