Clonal regulatory T cells specific for a red blood cell autoantigen in human autoimmune hemolytic anemia

Abstract

Regulatory T (Tr) cells have the potential to treat immune-mediated disease, but cloning such cells for study from patients with autoimmune disease has proven difficult. Here, we describe autoantigen-specific, interleukin-10 (IL-10)–secreting Tr cell clones recovered ex vivo from a patient with autoimmune hemolytic anemia (AIHA) and characterize their phenotype, origin, and regulatory function. These IL-10+ Tr cells recognized a peptide, 72H-86L, derived from the Rh red blood cell autoantigen and shared phenotypic characteristics with both natural and inducible Tr cells. The clones also expressed different Tr markers depending on activation state: high levels of CD25 and LAG-3 when expanding nonspecifically, but FoxP3 after activation by the autoantigen they recognize. Despite a discrete Tr phenotype, these cells stably expressed the T helper 1 (Th1) signature transcription factor T-bet, suggesting they derive from Th1 T cells. Finally, the contribution of CTLA-4 in activating these IL-10+ Tr cells was confirmed by analyzing responses to transgenic B7.1-like molecules that preferentially bind either CD28 or CTLA-4. Overall, these Tr cells have a functional phenotype different from those described in previous studies of human Tr populations, which have not taken account of antigen specificity, and understanding their properties will enable them to be exploited therapeutically in AIHA.

Type 1 regulatory T cells are associated with persistent split erythroid/lymphoid chimerism after allogeneic hematopoietic stem cell transplantation for thalassemia

“…A recent report described the presence of Rhesus peptide-specific IL-10-secreting Treg cell clones in the spleen of a patient with autoimmune hemolytic anemia. 51 These findings, together with the isolation of activated autoreactive T cells specific to human red blood cell auto-antigens, 52 demonstrate the existence of both regulatory and effector T cells specific to erythroid antigens.…”

Generation and expansion of regulatory human CD4+ T-cell clones specific for pancreatic islet autoantigens

“…Tr1 type Treg, defined by IL-10 expression, had specificity for the skin autoantigen desmoglein 3 in pemphigus vulgaris [31] and for a red cell autoantigen in haemolytic anemia [32]. CD4 þ CD25 þ Treg specific for platelet glycoprotein peptides were induced in vitro from naïve (CD45RA þ ) CD4 þ CD25 À blood T cells of patients with autoimmune idiopathic thrombocytopenia [33].…”

Combination peptide immunotherapy suppresses antibody and helper T-cell responses to the RhD protein in HLA-transgenic mice

“…Although Treg cells are often considered anergic, they can proliferate after activation via the T-cell receptor, [45][46][47] and human Treg cells responsive to the RhD protein have been cloned. 13 IL-2 is well-known for its ability to reverse T-cell anergy, and could have been produced in our cultures by effector cells prior to their suppression, but may not be an absolute requirement for the propagation of all Treg types, particularly those of thymic origin. [48][49][50] Predominant expression of Helios within the expanded population suggests that it did contain a majority of committed, thymically derived Treg cells, rather than reflecting de novo induction of Foxp3.…”

“…[11][12][13] The vast majority of IgG antibody responses are dependent on T-cell help, and the production of antibodies specific for RBC, including anti-D, is no exception. 1,2,14,15 An attractive therapeutic approach is to deliver synthetic peptides containing the dominant epitopes recognized by Th-cells in such a way as to induce tolerance, rather than effector immune responses.…”