Engrafted maternal T cells in human severe combined immunodeficiency: Evidence for a T H2 phenotype and a potential role of apoptosis on the restriction of T-cell receptor variable β repertoire

Engraftment of transplacentally derived maternal T lymphocytes in infants with severe combined immunodeficiency (SCID) is caused by lack of rejection of the HLA-mismatched maternal T cells by the recipient's immune system. Although the engrafted T cells express surface activation markers, they are anergic.1O'Reilly RJ Keever CA Small TN Brochstein J The use of HLA-non-identical T-cell-depleted marrow transplants for correction of severe combined immunodeficiency disease.Immunodeficiency Rev. 1989; 1: 273-309PubMed Google Scholar Restriction of T-cell receptor variable β (TCRV-β) segment use has been demonstrated in engrafted maternal T cells,2Knobloch C Goldmann SF Friedrich W. Limited T cell receptor diversity of transplacentally acquired maternal T cells in severe combined immunodeficiency.J Immunol. 1991; 146: 4157-4164PubMed Google Scholar, 3Sottini A Quirós-Roldan E Notarangelo LD Malagoli A Primi D Imberti L. Engrafted maternal T cells in a severe combined immunodeficiency patient express T-cell receptor variable beta segments characterized by a restricted V-D-J junctional diversity.Blood. 1995; 85: 2105-2113PubMed Google Scholar but it remains to be explained how it occurs. The high IgE levels and eosinophilia typical of Omenn's syndrome, a SCID characterized by the emergence of a limited number of autoreactive endogenous T-cell clones, has been attributed to the T H2 phenotype of these cells.4Melamed I Cohen A Roifman CM Expansion of CD3+CD4-CD8- T cell population expressing high levels of IL-5 in Omenn's syndrome.Clin Exp Immunol. 1994; 95: 14-21Crossref PubMed Scopus (30) Google Scholar However, little is known about the T H phenotype of engrafted maternal T cells in other patients with SCID with elevated serum IgE levels and eosinophilia. In one such patient described here, the engrafted maternal T cells had a predominantly T H2 phenotype and a restricted pattern of TCRV-β gene use. In addition, evidence was obtained suggesting that the latter phenomenon might result from apoptosis. The patient, a female and second child of unrelated parents with a negative family history for immunodeficiency disease, was hospitalized at 3 months of age because of mild erythroderma, oral candidiasis, and failure to thrive. Moderate anemia (3,370,000/mm3; hemoglobin: 9.7 gm/dl) and leukocytosis (29,000/mm3; 20% neutrophils, 29% lymphocytes, 11% monocytes, and 40% eosinophils) with hypereosinophilia and elevated serum IgE levels (109 to 481 IU/ml) were present. The patient's serum immunoglobulin level was low (IgG, 50 mg/dl; IgA and IgM undetectable). Flow cytometric analysis showed the following percentages and absolute numbers of CD3 (39%, 3279/mm3), CD8+ (13%, 1093/mm3), CD4+ (35%, 2943/mm3) and CD2+ cells (70%, 5880/mm3). CD19+ cells were less than 1%. Virtually all CD3+ cells expressed the αβ T-cell receptor and were CD4+ and DR. No CD3/CD8 double-positive cells were detected, indicating that the CD8+ cells were CD3-. The similar percentages of CD8+ cells and of those coexpressing CD2/CD16 (15%) suggested an almost exclusive expression of CD8 on natural killer cells. In vitro cell cultures3Sottini A Quirós-Roldan E Notarangelo LD Malagoli A Primi D Imberti L. Engrafted maternal T cells in a severe combined immunodeficiency patient express T-cell receptor variable beta segments characterized by a restricted V-D-J junctional diversity.Blood. 1995; 85: 2105-2113PubMed Google Scholar with phytohemagglutinin, phorbol myristate acetate plus ionomycin, and anti-CD3 yielded abnormally low responses (<15% of controls); the defective response to anti-CD3 reached normal levels after addition of human recombinant IL-2. HLA typing by a microtoxicity assay revealed the exclusive presence of maternal haplotypes on both the patient's unseparated peripheral blood mononuclear cells and CD4+ enriched cells, whereas the CD8+ and CD4/CD8 double-negative cell subsets expressed both parents' haplotypes. In skin and lymph node biopsy specimens, CD4+ cells overwhelmed CD8+ cells, and in the skin most CD4+ cells were also CD45RO+. Features typical of graft-versus-host disease (GVHD) were evident in the skin biopsy specimens; the corticoparacortical area was largely depleted in the lymph nodes. Adenosine deaminase and purine nucleoside phosphorylase activities were normal. The above data allowed the diagnosis of a T-B- SCID with maternal engraftment of CD3/CD4 positive cells. Cytokine gene expression5Facchetti P Prigione I Ghiotto F Tasso P Garaventa A Pistoia V Functional and molecular characterization of tumor-infiltrating lymphocytes and clones thereof from a major-histocompatibility complex-negative human tumor: neuroblastoma.Cancer Immunol Immunother. 1996; 42: 170-178Crossref PubMed Scopus (44) Google Scholar showed IL-4 messenger RNA (mRNA) in the patient's CD3 cells but not in her CD3+ or her mother's CD3+ cells. It also showed IL-2 mRNA in both the patient's and her mother's CD3+ cells but not in the patient's CD3- cells. No IL-5 or interferon-γ mRNA were detected in any of the cell fractions studied, whereas tumor necrosis factor, IL-10, and TGF-β1 mRNA were found in all three cell subsets. Granulocyte-macrophage colony-stimulating factor (GM-CSF) and IL-3 mRNA were detected only in the patient's CD3- cells (Fig. 1, A). Expression of TCRV-β genes3Sottini A Quirós-Roldan E Notarangelo LD Malagoli A Primi D Imberti L. Engrafted maternal T cells in a severe combined immunodeficiency patient express T-cell receptor variable beta segments characterized by a restricted V-D-J junctional diversity.Blood. 1995; 85: 2105-2113PubMed Google Scholar revealed a restricted pattern of TCRV-β gene use in the patient's CD3 cells compared with maternal CD3+ cells (Fig. 1, B). Flow cytometry, after 24 hours of culture in complete medium and propidium iodide staining,6Nicoletti I Migliorati G Pagliacci MC Grignani F Riccardi C. A rapid and simple method for measuring thymocyte apoptosis by propidium iodide staining and flow cytometry.J Immunol Methods. 1991; 139: 271-279Crossref PubMed Scopus (4431) Google Scholar showed a significantly higher percentage of spontaneous apoptosis in the patient's (31.6%) than in her mother's (1.3%) CD3+ cells, and on microscopic examination of the patient's CD3- cells, an elevated degree of apoptosis was observed among cells with the features of monocytes (Fig. 1, C). In the infant with T–B– SCID with hypereosinophilia and elevated serum IgE levels reported here, the finding of an engraftment of maternal CD4+ lymphocytes indicates a proliferative advantage, or survival, of CD4+ over CD8+ cells. Absence of CD8+ cells in the bloodstream cannot be attributed to their preferential tissue recruitment because CD4+ infiltrates were predominant in both the skin and lymph nodes. In patients with SCID, the engrafted cells are preferentially either CD4+ or CD8+,2Knobloch C Goldmann SF Friedrich W. Limited T cell receptor diversity of transplacentally acquired maternal T cells in severe combined immunodeficiency.J Immunol. 1991; 146: 4157-4164PubMed Google Scholar but so far it is undetermined whether the type of SCID or the patient's and/or mother's HLA haplotype determines which subset is engrafted. The finding of IL-4 mRNA in the engrafted, but not in the maternal, control cells and the absence of interferon-γ mRNA in both samples demonstrates the T H2 phenotype of the engrafted cells and may explain the elevated serum IgE levels. In the absence of IL-5 transcript, the hypereosinophilia can be explained by the abundant expression of GM-CSF mRNA observed together with the faint band of IL-3 mRNA in the patient's CD3- subset, as such hematopoietic growth factors released by non-T-cells can induce eosinophil differentiation and expansion in vivo.7Clark SC Kamen R The human hematopoietic colony stimulating factors.Science. 1987; 236: 1229-1237Crossref PubMed Scopus (1199) Google Scholar A restricted TCRV-β gene pattern, often present in patients with SCID, was documented by the absent expression of 13 TCRV-β genes in engrafted (CD4+), but not in control (CD4+ and CD8+), maternal cells. Such a finding was unlikely because of their different subset compositions. TCRV-β gene use is similar in normal CD4 and CD8 subsets. It has been demonstrated that TCRV-β subsets predominant in the maternal T cells of patients with SCID are not specific for HLA,2Knobloch C Goldmann SF Friedrich W. Limited T cell receptor diversity of transplacentally acquired maternal T cells in severe combined immunodeficiency.J Immunol. 1991; 146: 4157-4164PubMed Google Scholar, 3Sottini A Quirós-Roldan E Notarangelo LD Malagoli A Primi D Imberti L. Engrafted maternal T cells in a severe combined immunodeficiency patient express T-cell receptor variable beta segments characterized by a restricted V-D-J junctional diversity.Blood. 1995; 85: 2105-2113PubMed Google Scholar leading to rejection of the hypothesis of clonotypic selection in response to host HLA. It is well known that absence of a costimulatory signal provided by antigen-presenting cells causes activated T-cell anergy and cell death.8Boussiotis VA Barber DL Nakarai T et al.Prevention of T cell anergy by signalling through the γc chain of the IL-2-receptor.Science. 1994; 226: 1039-1042Crossref Scopus (309) Google Scholar Thus it is tempting to speculate that the high rate of apoptosis observed in this patient's monocytes may have resulted in inefficient T-cell/monocyte interaction, leading to T-cell anergy and death and consequently to restricted TCRV-β repertoire by the engrafted T cells. Whether anergic T cells may contribute to monocyte/macrophage apoptosis is not known, but antigen-presenting cell lysis by anergic T-cell clones has been reported.9Go C Lancki DW Fitch FW Miller J. Anergized T cell clones retain their cytolytic ability.J Immunol. 1993; 150: 367-376PubMed Google Scholar As in other patients with SCID,1O'Reilly RJ Keever CA Small TN Brochstein J The use of HLA-non-identical T-cell-depleted marrow transplants for correction of severe combined immunodeficiency disease.Immunodeficiency Rev. 1989; 1: 273-309PubMed Google Scholar, 2Knobloch C Goldmann SF Friedrich W. Limited T cell receptor diversity of transplacentally acquired maternal T cells in severe combined immunodeficiency.J Immunol. 1991; 146: 4157-4164PubMed Google Scholar, 3Sottini A Quirós-Roldan E Notarangelo LD Malagoli A Primi D Imberti L. Engrafted maternal T cells in a severe combined immunodeficiency patient express T-cell receptor variable beta segments characterized by a restricted V-D-J junctional diversity.Blood. 1995; 85: 2105-2113PubMed Google Scholar anergy of the engrafted T cells in the proband is shown by lack of proliferative response to T-cell activators, as well as by the restoration of the patient's proliferative response to anti-CD3 monoclonal antibodies in the presence of IL-2. In fact, IL-2 is known to prevent anergy that occurs when T-cell signaling is triggered in the absence of a costimulatory signal.8Boussiotis VA Barber DL Nakarai T et al.Prevention of T cell anergy by signalling through the γc chain of the IL-2-receptor.Science. 1994; 226: 1039-1042Crossref Scopus (309) Google Scholar The similar intensity of the IL-2 transcripts in the mother's resting CD3+ cells and in the patient's activated CD3+ cells suggests that an inappropriate IL-2 transcription occurs in response to activation of the patient's cells. The mild cutaneous GVHD, a further confirmation of T-cell anergy, could in part be attributed to the presence of IL-10 and TGF-β1 transcripts, cytokines that exert an immunosuppressive effect, in the patient's CD3+ and CD3– cells. In conclusion, this report shows that engrafted maternal T cells in our patient with SCID had a T H2-type pattern of cytokine production and a restricted pattern of TCRV-β gene use, which may have resulted from elimination by apoptosis of cells rendered anergic by inefficient T-cell–monocyte/macrophage interaction. Both features can explain the mild degree of GVHD observed here and in other patients with SCID with maternal engraftment.1O'Reilly RJ Keever CA Small TN Brochstein J The use of HLA-non-identical T-cell-depleted marrow transplants for correction of severe combined immunodeficiency disease.Immunodeficiency Rev. 1989; 1: 273-309PubMed Google Scholar, 2Knobloch C Goldmann SF Friedrich W. Limited T cell receptor diversity of transplacentally acquired maternal T cells in severe combined immunodeficiency.J Immunol. 1991; 146: 4157-4164PubMed Google Scholar In this respect, animal models have shown that switch of alloreactive T cells to a type 2 cytokine phenotype has been associated with failure of acute GVHD induction after transplantation across both major histocompatibility complex class II and I barriers,10Krenger W Snyder KM Byon JCH Falzarano G Ferrara JLM. Polarized type 2 alloreactive CD4+ and CD8+ donor T cells fail to induce experimental acute graft-versus-host disease.J Immunol. 1995; 155: 585-593PubMed Google Scholar which suggests the possibility of new approaches to prevention and treatment of acute GVHD. Patients with SCID might provide a good model for the evaluation of this issue.