AUTHOR=Chauhan Anil K. TITLE=Human CD4+ T-Cells: A Role for Low-Affinity Fc Receptors JOURNAL=Frontiers in Immunology VOLUME=7 YEAR=2016 URL=https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2016.00215 DOI=10.3389/fimmu.2016.00215 ISSN=1664-3224 ABSTRACT=

Both lymphoid and myeloid cells express Fc receptors (FcRs). Low-affinity FcRs engage circulating immune complexes, which results in the cellular activation and pro-inflammatory cytokine production. FcRs participate in the internalization, transport, and/or recycling of antibodies and antigens. Cytosolic FcRs also route these proteins to proteasomes and antigen-presentation pathways. Non-activated CD4+ T-cells do not express FcRs. Once activated, naive CD4+ T-cells express FcγRIIIa, which, upon IC ligation, provide a costimulatory signal for the differentiation of these cells into effector cell population. FcγRIIIa present on CD4+ T-cell membrane could internalize nucleic acid-containing ICs and elicit a cross-talk with toll-like receptors. FcγRIIIa common γ-chain forms a heterodimer with the ζ-chain of T-cell receptor complex, suggesting a synergistic role for these receptors. This review first summarizes our current understanding of FcRs on CD4+ T-cells. Thereafter, I will attempt to correlate the findings from the recent literature on FcRs and propose a role for these receptors in modulating adaptive immune responses via TLR signaling, nucleic acid sensing, and epigenetic changes in CD4+ T-cells.