A high CNV of has been associated with psoriasis vulgaris in Han Chinese (14)

A high CNV of has been associated with psoriasis vulgaris in Han Chinese (14). to improve FcRIIIa (CD16a)-dependent natural killer (NK) cell ADCC due to the lack of fucosylation on the N-linked glycan at position N297 of the IgG1 heavy chain Fc-region, show decreased ADCC as compared to regularly fucosylated antibodies. Together, these data confirm FcRIIIb as a negative regulator of neutrophil ADCC toward tumor cells and a potential target for enhancing tumor cell destruction by neutrophils. Keywords: FcRIIIb, neutrophil, ADCC, cancer, granulocyte, Fc-receptor, CNV, glycoengineering Introduction Fc-receptors play a vital role in cancer immunotherapy by inducing ADCC and antibody dependent cellular phagocytosis (ADCP). Most cancer targeting therapeutic antibodies currently on the market are of the IgG F-TCF class, and thus human FcRs constitute the key receptors for ADCC during cancer immunotherapy (1). The principal FcR receptor on neutrophils required for mediating ADCC of solid cancer cells appears to be FcRIIa (2, 3), with ~30C60-thousand copies expressed per cell (4), sometimes in combination with the activating receptor FcRIIc, present on a minority of about 15C20% of Caucasian individuals (5). The Diphenylpyraline hydrochloride high affinity receptor FcRI (CD64) is only present on activated neutrophils, but does generally not contribute to ADCC Diphenylpyraline hydrochloride of solid cancer cells even when expressed (3). Both FcRI and FcRIIa signal via immunoreceptor tyrosine-based activation motifs (ITAM), encoded in the cytoplasmic tail of the receptors (FcRIIa) or in the associated -chain (FcRI). Lastly, neutrophils express the highly abundant, 100C200-thousand copies per cell, low affinity receptor FcRIIIb, which is a GPI-linked Fc-receptor that lacks intrinsic intracellular signaling capacity (4). This receptor is selectively present on neutrophils and on a subset of basophils (6). In spite of the lack for direct signaling through FcRIIIb evidence from a number of studies show that FcRIIIb cooperates together with other FcR in the context of the phagocytosis of opsonized microbes (7). This suggests that the abundantly expressed FcRIIIb primarily acts to facilitate enhanced recognition and that ITAM signaling via the other FcR, in particular FcRIIa, is sufficient, or at least instrumental, to trigger the phagocytic process. The FcRIIIb-encoding gene, locus on human chromosome 1, where it is prone to gene copy number variation (CNV) (9). The CNV of Diphenylpyraline hydrochloride ranges from very rare individuals with no CNV has been shown to affect various diseases, i.e., a low CNV of was shown to result in an increased susceptibility to autoimmune diseases like systemic lupus erythematosus (SLE) (11, 12), primary Sjogren’s syndrome (pSS) (12), Wegener’s granulomatosis (WG) (12) and rheumatoid arthritis (RA) (13). A high CNV of has been associated with psoriasis vulgaris in Han Chinese (14). Nevertheless, no enhanced susceptibility to bacterial or fungal infection was observed in very Diphenylpyraline hydrochloride rare individuals lacking FcRIIIb expression (15), also showing that their neutrophils were able to function normally in regards to phagocytosis and superoxide generation (16). In addition, several polymorphic variants of the gene, known as the NA1, NA2, and SH haplotypes exist (17, 18), which do not result in marked differences in IgG-affinity. On the level of neutrophil-mediated ADCC of cancer cells all polymorphic variants appear similarly effective (3), but neutrophils from NA1NA1 individuals have been reported to bind and phagocytose IgG-opsonized bacteria and red cells somewhat more effectively than their heterozygous NA1NA2 and homozygous NA2NA2 counterparts (19, 20). Neutrophils constitute a major first line of host immune defense against fungal and bacterial infection (21). After extravasation from blood circulation they can enter a variety of tissues, including solid tumors (22C25). And even though the role of neutrophils in cancer is complex, with evidence for both positive or negative effects on tumor development (26), it is clear that neutrophils can contribute to the destruction of cancer cells particularly upon treatment with cancer therapeutic antibodies, as demonstrated now in a variety of animal models (27C30). Recently, we have found that neutrophils destroy antibody-opsonized cancer cells by a unique cytotoxic mechanism, termed at a concentration of 1 1 mg/mL) for 10 min at 37C. ADCC Cancer cell lines were labeled with 100 Ci 51Cr (Perkin-Elmer) for 90 min at 37C. After 3 washes with PBS, 5 103 cells were incubated in RPMI medium supplemented with 10% fetal bovine serum, 2 mM L-glutamine,.