A new Fc receptor on mouse macrophages binding IgG3.

Abstract

Monoclonal antibodies to sheep erythrocytes (SRBC) have proved useful in identifying two Fc receptors on mouse macrophages, one for IgG2a, and one for IgG1 and IgG2b. We have used monoclonal IgG3 anti-SRBC to identify a third Fc receptor on mouse macrophages which binds IgG3 uniquely. This receptor is present on primary resident and thioglycolate-induced peritoneal macrophages and on some macrophage cell lines. The binding of IgG3-coated SRBC is inhibited by aggregated byt not monomeric IgG3, and not by IgG1, IgG2a, and IgG2b aggregates. It is unaffected by treating the macrophages with trypsin or cytochalasin B and occurs at both 4 degrees and 37 degrees C. IgG3, like all other IgG subclasses, mediates phagocytosis. We have also generated a variant macrophage line which bears the receptors for IgG1 and IgG2b and for IgG2a, but not for IgG3.

Linkage of Exogenous T-cell Epitopes to the 19-Kilodalton Region ofPlasmodium yoeliiMerozoite Surface Protein 1 (MSP119) Can Enhance Protective Immunity against Malaria and Modulate the Immunoglobulin Subclass Response to MSP119

“…The complex containing MSP1 33 is shed (7), and MSP1 19 is the only part of MSP1 that remains on the merozoite surface during parasite invasion of red blood cells (RBC) (6). The MSP1 19 region consists of two epidermal growth factor-like domains (8). A limited number of allelic variants of P. falciparum MSP1 19 occur, with minor amino acid differences between them, making MSP1 19 one of the most conserved regions of P. falciparum MSP1 (48,57).…”

“…The MSP1 19 region consists of two epidermal growth factor-like domains (8). A limited number of allelic variants of P. falciparum MSP1 19 occur, with minor amino acid differences between them, making MSP1 19 one of the most conserved regions of P. falciparum MSP1 (48,57). Importantly, MSP1 is expressed in other Plasmodium species and the processing that generates MSP1 19 appears to be similar (5,17,29,43), enabling the use of various malaria parasites and animal models for the study of MSP1 19 -induced protection.…”

“…However, the protective immunity induced by vaccination with recombinant P. yoelii MSP1 19 is mediated largely by antibodies (14,28,36). Passive transfer of MSP1 19 -specific antiserum or monoclonal antibodies (MAb) into naive mice suppressed an otherwise lethal P. yoelii infection (14,39,55), whereas vaccination with MSP1 19 failed to protect mice deficient in immunoglobulin -chains (28).…”

“…However, the protective immunity induced by vaccination with recombinant P. yoelii MSP1 19 is mediated largely by antibodies (14,28,36). Passive transfer of MSP1 19 -specific antiserum or monoclonal antibodies (MAb) into naive mice suppressed an otherwise lethal P. yoelii infection (14,39,55), whereas vaccination with MSP1 19 failed to protect mice deficient in immunoglobulin -chains (28). In contrast, immunization with defined MSP1 19 -derived T-cell epitopes does not induce protective immunity and transfer of T-cell lines from MSP1 19 -immunized mice does not confer protection to naive recipients (58).…”

“…P. falciparum MSP1 is expressed on the surfaces of merozoites and is proteolytically processed in two steps to generate first a complex of polypeptides including a 42-kDa fragment (MSP1 42 ) that is subsequently cleaved to a 19-kDa fragment (MSP1 19 ) and a 33-kDa fragment (MSP1 33 ). The complex containing MSP1 33 is shed (7), and MSP1 19 is the only part of MSP1 that remains on the merozoite surface during parasite invasion of red blood cells (RBC) (6). The MSP1 19 region consists of two epidermal growth factor-like domains (8).…”