Anti-IgG antibodies during immunotherapy with purified grass pollen extracts.

In a double blind study 40 patients were allocated specific immunotherapy (hyposensitization) with partially purified timothy extract or two timothy major allergens 19, 25. All patients had typical grass pollen hay fever, in 27% associated with grass pollen asthma and in 13% with birch pollen allergy. Serum IgG anti-IgG antibodies were determined after dithiothreitol treatment. Before hyposensitization, IgG anti-IgG titres greater than or equal to 9 were demonstrated in 45% of the patients. During hyposensitization IgG anti-IgG titres showed a slight initial increase followed by a decrease below pretreatment level. Neither increase nor decrease was statistically significant. Reactions to rabbit IgG F(ab')2 fractions were only obtained during hyposensitization. The occurrence of anti-IgG antibodies did no correlate with symptoms, side effects, or the level of allergen-specific IgG. In a previous study it was demonstrated that patients with multiallergy hyposensitized with combined allergen extracts showed a statistically significant increase in IgG anti-IgG titres during treatment. The increase failed to appear in the present patients allergic only to pollen and treated with purified allergen extracts. It is therefore suggested that a multiallergic condition and the combination and/or purification of allergen extracts administered during hyposensitization may influence the production of IgG anti- IgG antibodies.