Cloning and characterization of porcine Fc gamma receptor II (FcγRII)

Receptors for the Fc region (FcγRs) of IgG play a crucial role in the immune system and host protection against infection. In the present study, we describe the cloning, sequencing and characterization of porcine FcγRII. By screening a translated EST database with the protein sequence of the human FcγRII (CD32) we identified a putative porcine homologue. Using rapid amplification of cDNA ends (RACE), we isolated the full-length cDNA encoding porcine FcγRII from peripheral blood leucocyte RNA. The porcine FcγRII cDNA was 1488 bp long, encoding a 297 amino acid trans-membrane glycoprotein composed of two immunoglobulin-like extracelluar domains, a trans-membrane region and a cytoplasmic tail with an immunoreceptor tyrosine-based inhibitory motif (ITIM). The predicted amino acid sequence was found to be 67% and 52% identitical with human and mouse FcγRIIB. RT-PCR indicated porcine FcγRII transcripts expressed in liver, alveolar, mesenteric lymph node and PBLs. COS-7 cells transfected with the pig FcγRII cDNA were able to bind chicken erythrocytes sensitized with porcine IgG. Identification of porcine FcγRII will aid in the understanding IgG-FcγR interactions, and may help in developing new immunization protocols.