Biology subjects

ElTanbouly, M. A.

Publications and source records attributed to ElTanbouly, M. A..

3 recordsLinked to original sources

bioRxiv2025

Antibody Mediated Diversification of Primary and Secondary Immune Responses

Humoral immune responses are characterized by increasing antibody affinity and diversity over time. Increased affinity is mediated by a combination of immunoglobulin gene somatic mutation and iterative cycles of selection in germinal centers. Less is understood about how diversity increases. Here we examine the role of antibody feedback in diversifying immune responses in mice that produce B cells that are incapable of secreting antibodies. To this end, we produced two strains of mice, one that expresses only membrane and secreted forms of IgM, and a second that produces only the membrane bound form of IgM. Analysis of primary and secondary immune responses show that antibody feedback significantly diversifies both primary and secondary immune responses even when antibodies are present at levels that are 10-30 fold lower than physiologic. The data have significant implication for sequential vaccination approaches aimed at shepherding immunity to produce broadly neutralizing antibodies to highly diversified pathogens such as HIV-1 and Influenza. SummaryHumoral immune responses diversify over time but whether secreted antibodies influence this process is unknown. Using antibody secretion-deficient mice this study shows a profound impact of secreted antibodies on the evolution of B cell diversity after vaccination.

immunology↗

bioRxiv2024

Affinity maturation of antibody responses is mediated by differential plasma cell proliferation

Increased antibody affinity over time after vaccination, known as affinity maturation, is a prototypical feature of immune responses. Recent studies have shown that a diverse collection of B cells, producing antibodies with a wide spectrum of different affinities, are selected into the plasma cell (PC) pathway. How affinity-permissive selection enables PC affinity maturation remains unknown. Here we report that PC precursors (prePC) expressing high affinity antibodies receive higher levels of T follicular helper (Tfh)-derived help and divide at higher rates than their lower affinity counterparts once they leave the GC. Thus, differential cell division by selected prePCs accounts for how diverse precursors develop into a PC compartment that mediates serological affinity maturation.

immunology↗

bioRxiv2024

The role of VISTA engagement in limiting neutrophil-mediated inflammation

A growing body of evidence suggests that VISTA, an immune checkpoint inhibitory receptor, plays a central role in the regulation of innate immunity in the settings of inflammatory diseases and cancer. Neutrophils are among the cells that have the highest membrane density of surface VISTA. Targeting VISTA on neutrophils with an agonist antibody resulted in a striking reduction in their LPS-induced peripheral accumulation. Fc receptor engagement was required for anti-VISTA antibody to mediate its effects on neutrophils. Concomitant with reduced peripheral neutrophil cell numbers, anti-VISTA antibody treatment increased neutrophil cell death in the liver. In a murine model of neutrophil-mediated arthritis, agonist anti-VISTA antibody treatment ameliorated disease severity, which was associated with reduced myeloperoxidase activity in the joints. These studies add to a growing spectrum of negative regulatory functions that VISTA performs in controlling inflammation through the innate and adaptive arms of the immune system that has implications for translation into the clinic.

immunology↗