Induction of the Expression of an FcR for Monomeric Rat IgG2b on Rat Peritoneal Macrophages
The existence of receptors for the Fc moiety of mouse monomeric IgGs on mouse macrophages is well documented1 but, by contrast, far less is known about analogous Fc receptors (FcR) on rat macrophage populations. Our studies of rat macrophage FcR arose from observations made by other members of our department on the localisation of rat 125I-labelled anti tumour monoclonal antibodies (McAbs) administered to rats bearing (syngeneic)sarcomata possessing the specific antigens. It was found that non-specific uptake of antibody by normal tissues occurred predominantly in the spleen, was associated with use of rat antibodies of the IgG2b isotype and did not occur if F(ab’)2 fragments of IgG2b antibodies were used2. Subsequently, we were able to show that macrophages fron rat spleen bound monomeric rat 125I-IgG2b in vitro whilst, in similar conditions, the binding of monomeric IgGs of other subclasses could not be detected3. Macrophages from the peritoneal cavity of rats however bound far less 125I-IgG2b than macrophages from the spleen and the degree of binding varied with the batch of rats used as cell donors. The purpose of the experiments reported here was to investigate a possible relationship between the state of activation of rat macrophages and the expression of a receptor for rat IgG2b as it is reported that activation modulates the expression of FcR on mouse macrophages4.
KeywordsPeritoneal Macrophage Phorbol Myristic Acetate Mouse Macrophage Dioctyl Phthalate Proteose Peptone
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