Enhancement of humoral and cellular immunity with an anti‐glucocorticoid‐induced tumour necrosis factor receptor monoclonal antibody

Abstract

Summary Adjuvants, including antibodies to tumour necrosis factor receptor superfamily members, augment immune responses. One member of this family, glucocorticoid‐induced tumour necrosis factor receptor (GITR), is expressed at low levels on naive/resting T cells, B cells and macrophages, but at higher levels on T regulatory cells. The aim of this study was to determine the ability of a rat anti‐mouse GITR monoclonal antibody, 2F8, to stimulate murine humoral and cellular immunity in a prime boost model with particular attention to posology and antigen‐specific effects. 2F8 enhanced the humoral immune response to ovalbumin and haemagglutinin (HA) compared with controls and this enhancement was equal to or greater than that obtained in mice dosed with standard adjuvants. 2F8 F(ab′)2 fragments were as effective as intact antibody in boosting humoral immunity, indicating that FcR‐mediated cross‐linking of 2F8 is not required for efficacy. Moreover, the enhanced response was durable and antigen specific. Administration of 2F8 shifted the immune response towards a T helper type 1 response with significant enhancement of immunoglobulin G2a‐ and G2b‐specific anti‐HA antibodies, as well as enhanced cellular immunity as measured by ELISPOT. 2F8‐treated mice also generated significantly more neutralizing antibodies to HA than control mice. Our findings show that anti‐GITR is a robust, versatile adjuvant that, unlike commonly used adjuvants that primarily enhance humoral immunity, enhances both humoral and cellular immunity. These results support the continued development of anti‐GITR for such indications as haematological and solid tumours, chronic viral infections, and as a vaccine adjuvant.

Anaphylaxis caused by repetitive doses of a GITR agonist monoclonal antibody in mice

“…33,43 We found that mMT mice, which lack mature B cells, were protected from anaphylaxis caused by DTA-1 ( Figure 3E) We observed that neutralizing IL-4 considerably reduced anaphylaxis severity ( Figure 3F). …”

“…Although GITR is expressed at much lower levels on B cells than on CD4 1 T cells (supplemental Figure 6), we also examined whether B cells were required for DTA-1-induced anaphylaxis, because GITR agonist antibodies have recently been shown to have potent humoral adjuvant effects. 33,43 We found that mMT mice, which lack mature B cells, were protected from anaphylaxis caused by DTA-1 ( Figure 3E). Because CD4 We observed that neutralizing IL-4 considerably reduced anaphylaxis severity ( Figure 3F).…”

GITR+ regulatory T cells in the treatment of autoimmune diseases

“…The potentiation of effector T cells is due to three mechanisms: costimulation of CD4 + and CD8 + T cells, resistance of effectors to Treg regulatory activity, and inhibition of Treg activity. These effects were obtained by using mAbs against GITR (DTA-1 and 2F8) [90,91].…”

Authentic GITR Signaling Fails To Induce Tumor Regression unless Foxp3+ Regulatory T Cells Are Depleted

“…Cross-linking of GITR using agonistic anti-GITR mAb (DTA-1) generally enhances immune responses in animal models involving viral infection, tumors, and autoimmune disease (6)(7)(8)(9)(10)(11)(12). GITR is an excellent adjuvant for humoral and cellular responses using agonistic mAb (13). Because the functions of mAbs are controlled by their Fc regions, anti-GITR mAb DTA-1 (rat IgG2b) essentially requires activating FcgR, but not inhibitory FcgRIIB, to suppress tumor growth and to eliminate intratumoral Treg cells in vivo (14).…”