Activation of human neutrophils induced by immune complexes prepared with cationic and anionic fractions of normal IgG antibodies.

ABSTRACT

The authors have recently shown that the ability of immune complexes (IC) to trigger Fc gamma R-dependent cell responses can be dramatically enhanced when the isoelectric point (pI) of normal IgG antibodies is increased from 5.8-8.5 to 8.5-9.8 by treatment with 1-ethyl-3-2(3-dimethylaminopropyl) carbodiimide HCl and ethylene diamine. In the current work the authors analyse whether differences in the charge of normal IgG antibodies may also affect IC activity. Soluble IC (sIC) were prepared with (a) rabbit IgG antibodies to human IgG and anionic or cationic fractions of human IgG; and (b) bovine serum albumin (BSA) and anionic or cationic fractions of rabbit IgG anti-BSA antibodies. Similar abilities to bind to neutrophil surface were observed for sIC prepared with both anionic (anIC) and cationic fractions of IgG (catIC). Moreover, no differences were found when neutrophil shape change, chemiluminescence (CL) emission and elastase release were induced by either anIC or catIC. As in the case of sIC, particulate IC prepared with erythrocytes (E) and anionic or cationic fractions of specific IgG antibodies (IgG-E) showed no differences in their abilities to trigger either CL emission or ADCC. Taken together, these results suggest that the pI of normal IgG antibodies do not affect the ability of IC to trigger neutrophil responses mediated by receptors for the Fc portion of IgG antibodies (Fc gamma R).