Clinical implications of the polymorphic interaction of murine IgG2b and IgG1 with human Fc receptors

The FcgammaRIIa polymorphism in patients with chronic kidney graft rejection

The FcgammaRIIa receptors, which provide a crucial link between cellular and humoral components of the immune response, display allelic polymorphism. Individuals are homozygous for either arginine 131 (RR131) or histidine 131 (HH131) or are heterozygous for these two alleles (RH131). The HH131 genotype binds human IgG2 with high RR131 with low, and RH131 with intermediate affinity. The aim of the study was to evaluate the FcgammaRIIa polymorphism in patients with chronic kidney graft rejection. The study included 121 renal transplant recipients: 53 patients with long-term stable graft function and 68 with chronic allograft rejection. The distribution of FcgammaRIIa genotypes in patients with chronic kidney graft rejection did not differ significantly from that in patients with stable graft function. The results suggest that the FcgammaRIIa polymorphism is not an important genetic risk factor for chronic rejection of kidney allografts.

Role of polymorphic Fc receptor Fc gammaRIIa in cytokine release and adverse effects of murine IgG1 anti-CD3/T cell receptor antibody (WT31)

Anti-CD3 monoclonal antibody (mAb) OKT3 is immunosuppressive, but causes severe adverse effects during the first administration ("first-dose reaction"). These adverse effects are presumably caused by cytokine release that results from T-cell activation. In vitro, T-cell activation by anti-CD3 mAb requires interaction with monocyte Fc receptors. The Fc receptor for murine IgG1, Fc gammaRIIa, is polymorphic. In some individuals, murine IgG1 anti-CD3 mAb causes T-cell proliferation and cytokine release in vitro (high responders [HR]), whereas in individuals with the low-responder (LR) phenotype it does not. We have now investigated the role of this Fc gammaRIIa polymorphism in the release of cytokines in vivo and the occurrence of adverse effects after the administration of WT31, a murine IgG1 anti-CD3/T cell receptor mAb. WT31 caused an increase of plasma tumor necrosis factor-alpha in all four HR patients and none of the five LR patients. In all HR patients except one, plasma gamma-interferon and interleukin 6 also increased, and a first-dose response was observed, whereas no cytokine release or adverse effects occurred in any of the LR patients. WT31 caused lymphopenia in all HR and none of the LR patients. FACS analysis demonstrated that in HR patients, after the initial disappearance of CD3+ cells from peripheral blood, modulation of CD3 occurred, whereas in LR patients a high degree of coating of the lymphocytes was observed. Surprisingly, WT31 also induced a marked granulocytopenia, as well as a decrease of thrombocytes, in three of the four HR patients (and in none of the LR patients). These data provide direct clinical evidence that Fc receptor interaction determines the release of cytokines and the occurrence of adverse effects after administration of anti-CD3/T cell receptor mAb. Furthermore, these data suggest that tumor necrosis factor-alpha by itself is not sufficient to induce the first-dose reaction.

Performance of CD3xCD19 bispecific monoclonal antibodies in B cell malignancy

Bispecific monoclonal antibodies, with a dual specificity for tumor associated antigens on target cells and for surface markers on immune effector cells, have been shown (in vitro) to be effective in directing and triggering effector cells to kill target cells resulting in target cell lysis. Bispecific monoclonal antibodies (BsAb) against the CD3 antigen on T cells and the CD19 antigen on B cell were developed. Data obtained by in vitro experiments might indicate that clinical responses in BsAb immunotherapy, will only be obtained in patients with minimal tumor load, and may need additional T cell stimulation via cytokines such as IL-2. Although these experiments have shown us their limitations, they also include the promise of BsAb-directed immunotherapy in B cell malignancy as further demonstrated during a Phase I trail, showing little toxicity. Clearly, much remains to be done before this BsAb is routinely used for therapy, but, the results presented show that the CD3xCD19 BsAb has a potential as a therapeutic agent in B cell malignancy. This report describes the experiments performed to test a new immunotherapeutic approach for the treatment of B cell malignancy. Bispecific antibodies are described that can target cytotoxic T cells to tumor cells and elicit a cytolytic action towards these cancer cells.