Participation of immunoglobulin and the alternative complement pathway in opsonization of Bacteroides fragilis and Bacteroides thetaiotaomicron

The Journal of Infectious Diseases
A B Bjornson, H S Bjornson


Studies were conducted to determine the requirements for immunoglobulin and complement for opsonization of Bacteroides fragilis and Bacteroides thetaiotaomicron. The ability of human sera depleted of immunoglobulin or complement components to promote phagocytosis and intracellular killing of the strains of Bacteroides by human leukocytes was measured in vitro under anaerobic conditions. Neither hypogammaglobulinemic sera nor pooled normal human serum (PNHS) heated at 56 C for 30 min supported phagocytosis and killing of the strains of Bacteroides. Sera depleted of terminal complement components by treatment with inulin or cobra venom factor and C8-deficient human serum did not support phagocytosis of the test strains. PNHS depleted of C3, factor B, or factor D also did not support phagocytosis of either strain. Dose-dependent restoration of the opsonic activity of factor B-depleted serum was accomplished by purified human factor B but not by human C2. The results indicated that immunoglobulin and components of the alternative complement pathway participate in opsonization of the strains of Bacteroides tested in this study.


Mar 1, 1987·The Journal of Experimental Medicine·A B BjornsonH S Bjornson

Related Concepts

Bacteroides fragilis
Complement Pathway, Alternative
Complement 2
Complement C4, Precursor
Complement component C6
Complement Component C8 gamma
Cavia porcellus

Related Feeds

Antibody-Dependent Cell Cytotoxicity

Antibody-dependent cellular toxicity refers to the lysis of a target cell by a non-sensitized effector cell of the immune system as a result of antibodies binding to the target cell membrane and engaging the Fc receptors on the immune effector cells. Find the latest research on antibody-dependent cellular toxicity here.

Antibodies: Complement Activation

The complement system can be activated by antigen-associated antibody. In the classical pathway of complement activation, C1q, C4b, and C3b are all able to bind to the Fc portion of IgG or IgM. Find the latest research on antibodies and complement activation here.

Alternative Complement Pathway

The Alternative Complement Pathway is part of the innate immune system, and activation generates membrane attack complexes that kill pathogenic cells. Discover the latest research on the Alternative Complement Pathway.