The Hooks without bait theory: mechanisms involved in the immunomodulatory effect of IgG on the thymic modulation of TCD4, TCD8, gdT, iNKT MAIT and B cells, focus on atopic diseases and COVID-19

Abstract

Although used for therapeutic purposes in various pathological processes with immunological etiology for many years, the precise mechanisms by which IgG antibodies can modulate immunity in the absence of antigen are not known, especially when considering their possible role in primary lymphoid organs such as the thymus. In recent years, several studies have shown that IgG can effectively play a modulatory role in lymphocyte differentiation in the thymus. This effect seems to be dependent on the idiotypic IgG repertoire, as it occurs in the absence of antigens and induces functional changes in several cell populations matured in the thymus, including several populations of human T and B lymphocytes. Based on the literature, especially on findings resulting from the therapeutic use of purified IgG (IVIg) and recent evidence obtained by our group, we have recently proposed the "hooks without bait" immunological theory. In this proposal, we aim to elucidate the cellular and molecular mechanisms involved in the aforementioned hypothesis to generate evidence that collaborates with the understanding of the mechanisms of thymic differentiation of TCD4, TCD8, gamma-deltaT, iNKT, MAIT, and B lymphocytes at the individual cellular transcriptional level as well as with the future development of therapies that use the transfer of IgG antibodies as a means of regulating human immunity. (AU)