C. psittaci 6 BC soluble hemagglutinin: factors influencing the red cell receptor sites.

Human blood-group A, B and O erythrocytes did not possess receptor sites for either crude or ether-ethanol extracted chlamydial soluble hemagglutinin. Sensitive chicken erythrocytes were agglutinated to higher titres by ether-ethanol extracted than by crude chlamydial hemagglutinin. Studies indicated that trypsin-, chymotrypsin-, neuramanidase-sensitive receptor sites were not essential for binding of ether-ethanol extracted chlamydial hemagglutinin; neither were beta-glucuronidase- nor periodate-sensitive receptor sites essential. Since soluble chlamydial hemagglutinin consists of components of host cells and that of chlamydiae purification of hemagglutinin from chlamydiae is required in future studies.