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Identification of Immunosuppressive Factors in Normal Pregnant Serum Affecting Antibody Dependent Cell‐Mediated Cytotoxicity
Author(s) -
Yabushita Hiromitsu,
Sawaguchi Keizo,
Ishihara Minoru,
Itoh Yusei
Publication year - 1987
Publication title -
asia‐oceania journal of obstetrics and gynaecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.597
H-Index - 50
eISSN - 1447-0756
pISSN - 0389-2328
DOI - 10.1111/j.1447-0756.1987.tb00017.x
Subject(s) - antibody dependent cell mediated cytotoxicity , effector , antibody , receptor , immune system , lymphocyte , immune receptor , cytotoxicity , chemistry , immunology , mechanism of action , endocrinology , biology , medicine , biochemistry , in vitro , monoclonal antibody
The antibody dependent cell‐mediated cytotoxicity (ADCC) activity of peripheral blood lymphocytes was found to be lower in women experiencing normal pregnancy than in nonpregnant females. This decrease was especially striking during the early stage of pregnancy. It was determined that this decrease is caused by two suppressive factors contained in the pregnant serum. One was a high‐molecular‐weight substance with strong suppressive activity, which was not reduced even when the effector cells were washed. This factor showed binding to IgG Fc‐receptors on the lymphocyte surface and to Protein A. Its ability to suppress ADCC activity was eliminated when precipitation was performed with 4% polyethylene glycol. On the basis of these characteristics, it was surmised that this suppressive factor is an IgG‐immune complexlike substance. The suppressive mechanism of this substance is speculated to be competitive binding to the IgG Fc‐receptors of effector cells, which thereby inhibits the binding of specific antibody to these cells. The second suppressive factor was of low molecular weight, and its activity was lost when the effector cells were washed. This factor did not bind to IgG Fc‐receptors, and it is speculated that the action mechanism of this substance must involve direct action against the ADCC reaction system, thereby inhibiting the cellular metabolism of the effector cells. Moreover, it was demonstrated that in normal pregnancy there is a positive correlation between the circulating immune complex concentration in the serum and the serum's suppressive effect on the ADCC activity. This finding suggests that the immune complex‐like substance is the principal factor in the suppression of the ADCC activity.