The lymphoproliferative response to enzymatically digested gelatin in subjects with gelatin hypersensitivity

Background This study was designed to evaluate the immunogenic characterist ics of enzymatically digested gelatin, 'FreAlagin', employing the lymphopro liferative response in subjects with gelatin hypersensitivity. Our purpose was to assess the response of primed lymphocytes to the newly developed Fre Alagin and compare it to the response to conventional gelatin. Methods A gelatin-specific lymphocyte proliferation test (LPT) was performe d in 110 children with adverse reactions to gelatin-containing vaccines, wh o showed positive gelatin-specific cell-mediated immunity and were thus dia gnosed as having gelatin hypersensitivity. Gelatin-specific IgE was measure d in all subjects. The antigenic activity of FreAlagin to lymphocytes was c ompared with that of conventional bovine gelatin. Positive and negative con trol specimens were obtained from the patients with anaphylaxis and from su bjects inoculated with gelatin-free vaccine who showed no adverse reactions in order to establish the fluorometric ELISA system to determine IgE antib ody to gelatin and LPT. Results The lymphocyte activity against FreAlagin was much less than that t o Wako gelatin and more than half of the subjects who reacted positively to Wako gelatin had a negative LPT to FreAlagin. Although 47% of the subjects had positive LPTs to FreAlagin, all but two still had lower SIs to FreAlag in compared with Wako gelatin. Conclusion We conclude that the antigenic activity of FreAlagin as measured by the cell-mediated immune response is significantly less than that of co nventional bovine gelatin. However, it is still necessary to perform clinic al trials to show a reduced or absent clinical reactivity to FreAlagin in s ensitized patients to conventional gelatin.