Side Effects during Immunotherapy with Purified Grass Pollen Extracts

In a 3-year prospective double blind study, grass pollen allergic patients were allocated to perennial hyposensitization with the timothy major allergens Nos. 19 and 25 (2-component extract) or a 20-component timothy extract. The extracts were biologically standardized and adsorbed to aluminium hydroxide for treatment.
Systemic side effects (SSE) had début after 1 1/2–5 h and lasted without treatment 1/2–10 h. Treatment with the 2-component extract showed preponderance of minor SSE (arthralgia, rhinitis, tiredness, headache, conjunctivitis, nausea, flu-like symptoms), but major SSE (urticaria, angioedetma, asthma) were equally distributed between treatment with the two timothy extracts.
Major SSE comiplicated the treatment before the first grass pollen season in 33% of the patients vs. only in 3% during the subsequent perentiial therapy, and developed (92%) at high single dose of ≥1,000 biological units. The majority (69%) were later able to reach the same or higher dose without relapse. Most (62%) patients with major SSE were predicted by high nasal sensitivity before treatment.
Only 18% of the patients had immediate local skin reactions of ≥2 cm, but delayed local side effects of ≥10 cm were recorded in 70%. Immediate skin reactions did not correlate with delayed skin reactions or with SSE, but delayed local side effects tended towards negative correlation with major SSE. A mean area reduction of 50% of the delayed skin reactions was recorded by repetition of a single dose.
Subcutaneous nodules appeared at single doses of ≥5,000 biological units. Only 5% of the patients contracted nodules during initial preseasonal therapy compared with 38% during subsequent perennial dosage. The nodules contained typical benign granulomas, and the frequency in the two groups was proporitonate to the quantity of aluminium in the two extracts.