Role of immunoconglutinin in resistance to infection. The in vitro promotion of phagocytosis by immunoconglutinin.

The role of immunoconglutinin (IK) in phagocytosis was investigated using an in vitro opsonic test system. Phagocytosis of Gram-negative bacteria was increased when pre-treated with rabbit serum containing immunoconglutinin. The enhanced phagocytosis was reflected by an increase in the number of macrophages engaged in phagocytosis as well as an increase in the opsonic index. Heat inactivation of the sera completely destroyed this opsonic activity. The data indicate that immunoconglutinin potentiates the opsonic activity of serum by increasing the amount of complement fixed to the bacteria. IK may also influence the rate of phagocytosis by providing immune aggregates of suitable size, thus facilitating ingestion of immune complexes.