Receptor for immunoglobulin Fc on pathogenic but not on nonpathogenic protozoa of the Trypanosomatidae.

Abstract

The mechanisms parasites have developed to escape immune surveillance are currently under investigation in many laboratories, because their elucidation may provide new approaches to the prevention of the diseases the parasites cause. For a detailed description and experimental evidence of these various mechanisms, see the recent review by Bloom (1).One possible means of evasion is the uptake of host antigen by the parasite (2). This phenomenon has been amply studied and documented in schistosomiasis. The acquisition of mouse antigens (3-5), human A, B, and H blood group antigens (6, 7), glycolipids from erythrocytes (8), serum factors (9-11) and, more recently, mouse histocompatibility antigens (12) have been demonstrated in this parasite and offer an effective mechanism for antigenic mimicry of the host and subsequent escape from the immune response.This same parasite has been used to study the possibility of immunological blockade (13). Host immunoglobulin has been shown to occur on the surface of Schistosoma mansoni (14,15), and it has also been determined that this immunoglobulin is heterospecific, excluding the possibility of a specific parasite-antigen host-antibody interaction (15). These studies also suggest that the host immunoglobulin adsorbed by the parasite is oriented so as to have a Fab region of the molecule available, possibly representing a specific binding of the immunoglobulin through a receptor for Fc present on the membrane of S. mansoni, Indeed, receptors for IgG Fc, human fl2-microglobulin (16), and Clq (17) on this parasite have recently been reported.

The Fc Domain of Immunoglobulin Is Sufficient to Bridge NK Cells with Virally Infected Cells

“…It is also highly likely that FcBCC is at least in part responsible for the rapid NK cell clearance of oncolytic HSV1 in the setting of malignant glioma (Alvarez-Breckenridge et al, 2012), and clearance of infection by many other members of the herpesviridae family encoding similar or identical Fc-binding proteins (Corrales-Aguilar et al, 2014; De Miranda-Santos and Campos-Neto, 1981; Litwin et al, 1992; Loukas et al, 2001; Olson et al, 1997; Sprague et al, 2008). Given the presence of IgG binding proteins in many different pathogens, FcBCC may have broad implications in controlling infectious diseases.…”

The relative contribution of antibody production and CD8+ T cell function to immune control of Trypanosoma cruzi

“…The role of antibody production as a secondary mechanism of immune control can be explained by the requirement for these antibodies to mediate or potentiate the clearance of released amastigotes. Antibodies may also be important in the killing of trypomastigotes although a considerable body of literature documents the multiple mechanisms by which trypomastigotes of T. cruzi may evade such antibody‐mediated destruction (De Miranda‐Santos and Compos‐Neto, 1981, Krettli and Brener, 1982, Schenkman et al . 1986, Sher et al .…”

Cloning and Characterization of a Gene Encoding an Immunoglobulin-Binding Receptor on the Cell Surface of Some Members of the FamilyTrypanosomatidae

“…In realty, approximately 10 times more normal IgG was required to provide the same levels of fluorescence intensity given by the IgG anti-Lmsp1 antibody. Indeed, the binding of normal immunoglobulin to an immunoglobulin ligand on the cell surface (Fc-like receptor) of members of the family Trypanosomatidae was proposed many years ago (20) and has been confirmed (25,35). However, the results presented here with purified rabbit IgG anti-Lmsp1 antibody clearly showed that the fluorescence intensity observed with this purified antibody molecule was markedly higher than the fluorescence intensity given by immunoglobulins present in the normal rabbit serum.…”

“…It is believed that these parasite ligands offer both an effective mechanism for antigen mimicry of the host antigens and an effective system for the internalization of the parasites in their target host cells. One possible parasite noncognitive ligand of immunoglobulins is an Fc-like receptor present on the cell surface of several members of the Trypanosomatidae (20,25,35). Indeed, immunoglobulins and purified Fc fragments of immunoglobulin G (IgG) have been shown to facilitate the internalization of Trypanosoma cruzi in their host cells and to consequently increase the infective capacity of these parasites (1,22,23,35).…”