Search for potent immunostimulating agents from plants and other natural sources.- Chemistry, analysis and immunological investigations of Echinacea phytopharmaceuticals.- Immunologically active polysaccharides from Echinacea purpurea plant and cell cultures.- Clinical investigations of Echinacea phytopharmaceuticals.- Benefit and risks of the squeezed sap of the purple coneflower (Echinacea purpurea) for long-term oral immunostimulant therapy.- Low-molecular weight compounds with complement activity.- Complement-activating polysaccharides from medicinal herbs.- Lentinan and other antitumoral polysaccharides.- Mistletoe lectins as immunostimulants (chemistry, pharmacology and clinic).- Saponins as immunoadjuvants and immunostimulants.- Garlic as an immunostimulant.- Immunostimulants in Ayurveda medicine.- Immunostimulants in traditional Chinese medicine.