Engineered antibodies of IgG1/IgG3 mixed isotype with enhanced cytotoxic activities.

Enhancement of multiple effector functions of an antibody may be a promising approach for antibody therapy. We have previously reported that fucose removal from Fc-linked oligosaccharides greatly enhances antibody-dependent cellular cytotoxicity (ADCC) of therapeutic antibodies. Here, we report a unique approach to enhance complement-dependent cytotoxicity (CDC), another important effector function of antitumor antibodies, by using engineered constant region of human IgG1/IgG3 chimeric isotypes. We systematically shuffled constant domains of IgG1 and IgG3 to generate a comprehensive set of mixed chimeric isotypes of anti-CD20 antibodies. Among these, the variant 1133, consisting of the CH1 and the hinge each from IgG1 and the Fc from IgG3, was unexpectedly found to exhibit markedly enhanced CDC that exceeded wild-type levels. However, it lacked protein A-binding capacity, an important feature for the industrial production. To eliminate this deficiency, a portion in COOH-terminal CH3 domain of 1133 was substituted with IgG1, resulting in full recovery of protein A binding without compromising the enhanced CDC and ADCC activities. The CDC-enhancing effect using a chimeric isotype was also shown in CD52 antigen/antibody system. The ADCC activity of the variants was also maximized by the absence of fucose from its carbohydrate structure, a phenomenon that has previously been observed for wild-type antibodies. Enhanced cytotoxicity of a variant was confirmed in a cynomolgus monkey model. These findings suggest that the variant antibodies with IgG1/IgG3 chimeric constant regions and nonfucosylated oligosaccharides that possess dual-enhanced cytotoxic functions may be an improvement for the next generation of therapeutic antitumor antibodies.

Shortening of the induction period of allergic asthma in cynomolgus monkeys by Ascaris suum and house dust mite.

The development of non-human primate models of asthma requires a period of time (e.g., 0.5-1 year). To develop the models in a short period, male cynomolgus monkeys were sensitized with dinitrophenyl-Ascaris suum (DNP-As) allergen by intraperitoneal and intramuscular injection and by intratracheal inhalation. All sensitized animals developed positive intradermal skin reaction to DNP-As. Sensitization elevated allergen-specific IgE levels in serum, the number of CCR4-positive T helper lymphocytes in peripheral blood, and IL-4 and IL-5 releases from phorbol 12-myristate 13-acetate- and ionomycin-stimulated peripheral blood. In addition, allergen challenge induced increases in lung resistance, airway inflammation, and hyperresponsiveness to inhaled methacholine. Next, animals were sensitized with house dust mite extracts (HDM) under the similar procedure. In these animals sensitized with DNP-As or HDM, inhaled fluticasone propionate and oral prednisolone inhibited the allergen-induced airway hyperresponsiveness. Taken together, monkey asthma models were successfully developed by sensitization with DNP-As or HDM under a short-term protocol (within 7 weeks). These models should be useful for the evaluation of anti-inflammatory drugs for asthma treatment.