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[Fc gamma receptors in health and disease]
F Flores-Borja1, E Santiago, B Weiss-Steider
1Unidad de Investigación en Diferenciación Celular y Cáncer, Facultad de Estudios Superiores Zaragoza UNAM, México D.F.
Receptors for the Fc fragment of immunoglobulins G (Fc gamma R) belong to the immunoglobulin superfamily and are expressed on different cell types. These receptors are classified in three different groups (Fc gamma RI, Fc gamma RII and Fc gamma RIII) depending upon their molecular weight, affinity and specificity for their ligands. In addition to all these differences, genetic polymorphisms induce the expression of several isoforms, making the Fc gamma R a heterogeneous group. The Fc gamma Rs have been the subject of intense research on their gene organization, biochemical and structural properties. It has also been established that the Fc gamma R play an important functional role on the regulation of the biological responses that are triggered during inflammatory stages (e.g. an infection), as they link the cellular and humoral branches of the immune response. In this article we give examples of the participation of Fc gamma R on the regulation of the immune response as well as the activation of intracellular mechanisms (transduction signals) after the crosslinking of Fc gamma R by antigen-antibody complexes. The effect of cytokines and growth factors on the regulation of Fc gamma R expression is also described. We discuss the importance of the possible use of some of these molecules to control the expression of Fc gamma R in some clinical situations where alterations on their expression are associated with some diseases. Finally, we analyze the role of Fc gamma R as the point of entry of infectious agents such as HIV.
Receptors for the Fc fragment of immunoglobulins G (Fc gamma R) belong to the immunoglobulin superfamily and are expressed on different cell types. These receptors are classified in three different groups (Fc gamma RI, Fc gamma RII and Fc gamma RIII) depending upon their molecular weight, affinity and specificity for their ligands. In addition to all these differences, genetic polymorphisms induce the expression of several isoforms, making the Fc gamma R a heterogeneous group. The Fc gamma Rs have been the subject of intense research on their gene organization, biochemical and structural properties. It has also been established that the Fc gamma R play an important functional role on the regulation of the biological responses that are triggered during inflammatory stages (e.g. an infection), as they link the cellular and humoral branches of the immune response. In this article we give examples of the participation of Fc gamma R on the regulation of the immune response as well as the activation of intracellular mechanisms (transduction signals) after the crosslinking of Fc gamma R by antigen-antibody complexes. The effect of cytokines and growth factors on the regulation of Fc gamma R expression is also described. We discuss the importance of the possible use of some of these molecules to control the expression of Fc gamma R in some clinical situations where alterations on their expression are associated with some diseases. Finally, we analyze the role of Fc gamma R as the point of entry of infectious agents such as HIV.