Preparation of allergen extracts from the green alga Chlorella. Studies of growth variation, batch variation, and partial purification.

Allergen extracts were prepared from different raw materials of three strains of the unicellular green alga Chlorella (C. vulgaris, C. homosphaera and C. saccharophila). Growth variation, batch variation and composition of partially purified extracts were studied by analyzing total protein and carbohydrate content, protein and IgE-binding patterns and allergenic potency. Chlorella allergens were produced in the same proportions in early and late exponential growth phases but appeared partly degraded in the stationary phase. Uniform growth and extraction from Chlorella cells in the late exponential phase were demonstrated. Partially purified extracts from cells in late exponential phase contained 50% protein of the dry weight compared to 20% in crude extracts. The carbohydrate content was 20-30% of the dry weight of both crude and purified extracts. The allergenic potency of the purified extracts was 150-340% of the crude extracts, as assayed by RAST inhibition. The purified C. vulgaris extract showed a reduced IgE binding compared to crude extracts, while C. homosphaera and C. saccharophila extracts exhibited consistent IgE binding and are therefore suitable for in vivo and in vitro studies of allergenic properties of Chlorella.