CD32, also called FcγRII or FCGR2, is a glycoprotein surface receptor found on the surface of various immune cells. This receptor belongs to the Ig gene superfamily and has two primary functions: regulation of cellular responses and uptake of immune complexes in the form of IgG antibodies. While CD32 has a low affinity for the Fc region of IgG antibodies in their monomeric form, it has high affinity for IgG immune complexes.
CD32 plays a crucial role in cellular responses, which include phagocytosis, cytokine stimulation, and endocytic transport. When dysregulated or abnormal, CD32 is associated with several forms of autoimmunity, including systemic lupus erythematosus.
A study of recurrent bacterial respiratory tract infections and systemic meningococcal infections suggests that alleles encoding histidine at amino acid position 132, which are associated with greater opsonic activity, are less common in the disease group. Additionally, studies of invasive pneumococcal disease showed nearly threefold higher frequency of individuals homozygous for codon changes in the mannose-binding lectin gene.
CD32 is preferentially expressed in latently HIV-1-infected cells in an in vitro model of quiescent CD4 T cells. When CD4+ T cells are stimulated with IL-2, IL-7, PHA, and anti-CD3/CD28 antibodies, they undergo T-cell proliferation, which causes co-expression of CD32 and activation of the markers HLA-DR and CD69. HIV-1 infection also increases CD32 expression in the CD4+ T cells of HIV-positive individuals. There is no marked difference in provirus integration or replication-competent latent HIV-1 in CD32+ or CD32− CD4+ T cells from HIV+ individuals.
FAQs
What is CD32?
CD32, also known as FcγRII or FCGR2, is a glycoprotein surface receptor found on the surface of various immune cells. This receptor belongs to the Ig gene superfamily and has two primary functions: regulation of cellular responses and uptake of immune complexes in the form of IgG antibodies.
What are the functions of CD32?
CD32 primarily regulates cellular responses, which include phagocytosis, cytokine stimulation, and endocytic transport. It also plays a role in the uptake of immune complexes in the form of IgG antibodies.
What are the implications of abnormal CD32 expression?
When dysregulated or abnormal, CD32 is associated with several forms of autoimmunity, including systemic lupus erythematosus.
What is CD32’s role in HIV?
CD32 is preferentially expressed in latently HIV-1-infected cells in an in vitro model of quiescent CD4 T cells. HIV-1 infection also increases CD32 expression in the CD4+ T cells of HIV-positive individuals. There is no marked difference in provirus integration or replication-competent latent HIV-1 in CD32+ or CD32− CD4+ T cells from HIV+ individuals.
Conclusion
CD32 is an essential receptor in immune cells that plays a critical role in cellular responses and uptake of immune complexes. Dysregulated CD32 is associated with several autoimmune diseases, while its role in HIV amplifies its significance in the medical field.
