Growth inhibition of clonogenic leukemic precursor cells by minor histocompatibility antigen-specific cytotoxic T lymphocytes.

Minor histocompatibility (mH) antigens appear to play a major role in bone marrow transplantation (BMT) using HLA-identical donors. Previously, we reported the isolation of major histocompatibility complex (MHC)-restricted mH antigen-specific cytotoxic T lymphocytes (CTL) from patients with graft-vs.-host disease or rejection after HLA-identical BMT. We have demonstrated that mH antigens can be recognized on hematopoietic progenitor cells, and residual recipient CTL specific for mH antigens expressed on donor hematopoietic progenitor cells may be responsible for graft rejection in spite of intensive conditioning regimens in HLA-identical BMT. Here, we investigated whether mH antigen-specific CTL directed against the mH antigens HA-1 to HA-5 and the male-specific antigen H-Y were capable of antigen-specific inhibition of in vitro growth of clonogenic leukemic precursor cells. We demonstrate that mH antigen-specific CTL against all mH antigens tested can lyse freshly obtained myeloid leukemic cells, that these mH antigen-specific CTL can inhibit their clonogenic leukemic growth in vitro, and that this recognition is MHC restricted. We illustrate that leukemic (precursor) cells can escape elimination by mH antigen-specific CTL by impaired expression of the relevant MHC restriction molecule. We suggest that mH antigen-specific MHC-restricted CTL may be involved in vivo in the graft-vs.-leukemia reactivity after BMT.

Hypothyroidism during immunotherapy with interleukin-2 is associated with antithyroid antibodies and response to treatment.

PURPOSE: We investigated whether the association of interleukin-2 (IL-2) with hypothyroidism is related to the presence of thyroid autoantibodies, dose of IL-2, and clinical effectiveness of treatment, and reviewed the literature. PATIENTS AND METHODS: Sixteen cancer patients were treated with high-dose recombinant, continuous infusion IL-2 (18 x 10(6) IU/m2/d) and lymphokine-activated killer (LAK) cells. One patient previously treated for a toxic goiter with radioactive iodine was analyzed separately. Thyroid function and levels of thyroid antibodies were determined regularly. RESULTS: Seven of 15 patients (47%) became hypothyroid with high serum thyrotropin (TSH) levels within 60 to 120 days after the start of treatment; five responded favorably to treatment (one complete remission [CR], four partial remissions [PRs]), compared with none of the other eight patients. Two hypothyroid patients developed antimicrosomal antibodies (AMAs), one showed a further increase of antithyroglobulin antibodies (TgAbs), and six developed TgAbs. Only one of eight euthyroid patients developed slightly elevated TgAb levels. Development of hypothyroidism correlated significantly with a favorable response to treatment (r = .76, P = .001). The patient, treated with radioactive iodine, also became hypothyroid with high levels of TSH and development of AMAs and TgAbs. No difference was found between the hypothyroid and euthyroid patients in mean cumulative dose of IL-2 administered within the first 60 days or total treatment period, or with the relative dose-intensity. No other autoantibodies were found and patients had normal corticotropin (ACTH) stimulation tests. CONCLUSION: The likelihood of developing (transient) hypothyroidism is higher in patients who respond to IL-2 treatment. The development of antithyroid antibodies suggests that IL-2 treatment triggers autoreactive B-cell clones or that cellular and/or cytokine-mediated thyroid destruction leads to activation of autoreactive B-cell clones.

Comparison between clonogenic and cytotoxic assays for measuring LAK cell activity.

The antiproliferative effect of lymphokine-activated killer (LAK) cells was studied using a clonogenic assay in an attempt to find a model for predicting this effect in vivo or ex vivo (in the case of purging) in cancer treatment. The results were compared with the standard 51Cr-release cytotoxic assay. Cells from clonogenic neoplastic cell lines (K562 and HL-60) were plated in methylcellulose with LAK cells obtained from ten different donors in various effector-to-target (E:T) ratios. At E:T ratios of 16:1, elimination of greater than 90% of the clonogenic cells was seen in 20 of 21 experiments, whereas such lysis was incidentally found in the 51Cr-release assay. In almost all paired combinations, clonogenic cells tested in a colony assay were more sensitive to kill by LAK cells than the whole tumor cell suspensions measured in the 51Cr-release assay.

Recognition of minor histocompatibility antigens on lymphocytic and myeloid leukemic cells by cytotoxic T-cell clones.

Clinical studies indicated an enhanced antileukemic effect of allogeneic bone marrow transplantation (BMT), as compared with autologous BMT. After allogeneic HLA-identical BMT, donor-derived cytotoxic T lymphocytes (CTLs) directed at minor histocompatibility (mH) antigens on the recipients, tissues can be shown. To evaluate the antileukemic reactivity of mH antigen-specific CTLs, we analyzed the expression of mH antigens on circulating lymphocytic and myeloid leukemic cells. We show that the defined mH specificities HA-1 through HA-5 and H-Y are present on leukemic cells, indicating that mH antigen-specific CTLs are capable of HLA class I-restricted antigen-specific lysis of leukemic cells. Compared with interleukin-2-stimulated normal lymphocytes, leukemic cells of lymphocytic origin are less susceptible to T-cell-mediated cytotoxicity by the HA-2 mH antigen-specific CTL and the anti-HLA-A2 CTL clone. A possible explanation for this phenomenon is impaired expression of the LFA-1 adhesion molecule. Our study suggests that mH antigen-specific HLA class I-restricted CD8+ CTLs may be involved in the graft-versus-leukemia reactivity after allogeneic BMT.

Selective outgrowth of CD45RO+ V gamma 9+/V delta 2+ T-cell receptor gamma/delta T cells early after bone marrow transplantation.

Before and after bone marrow transplantation (BMT) for hematologic malignancies, peripheral blood mononuclear cells from 10 patients were obtained. The relative and absolute numbers of CD3+ T-cell receptor gamma delta+ (TCR gamma delta+) cells, as defined by the reaction of monoclonal antibodies (MoAbs) directed against CD3 and the TCR gamma delta (anti-TCR gamma delta-1), were determined. Before transplantation, eight of nine patients tested had less than 10% CD3+TCR gamma delta+ cells. Consistent increased numbers of gamma delta cells up to eightfold the pretransplant level can be seen in four of nine patients tested within the first 4 months after BMT. The large majority of early posttransplant gamma delta and alpha beta T cells express the CD45RO antigen, which is usually expressed on "memory" cells only. The V-region usage of the TCR gamma delta+ T cells was analyzed using fresh mononuclear cells and MoAbs against known V gamma and V delta regions. For more detailed analysis, CD3+TCR gamma delta+ cells were sorted and cultured in bulk and cloned. Using fresh cells and bulk cultures, mainly V gamma 9+V delta 1-V delta 2+ cells were found during engraftment. Only after 6 weeks post-BMT, V gamma 9-V delta 1+V delta 2- cells appear. Analysis of the V gamma and V delta usage at the clonal level confirmed the observation that early after BMT only V gamma 9+V delta 2+ cells are present, whereas gamma delta T-cell clones expressing other gamma delta TCR phenotypes can only be detected 4 to 6 weeks post-BMT. The predominance of V gamma 9+ cells during early engraftment could be explained by several mechanisms: (A) sequential rearrangements during T-cell development, leading to an early wave of V gamma 9+ cells, or (B) selective outgrowth of preexisting V gamma 9+V delta 2+CD45RO+ TCR gamma delta cells in the bone marrow graft, possibly as a result of antigen driven expansion due to exposure to environmental antigens.

Induction of CD11a/leukocyte function antigen-1 and CD54/intercellular adhesion molecule-1 on hairy cell leukemia cells is accompanied by enhanced susceptibility to T-cell but not lymphokine-activated killer-cell cytotoxicity.

Some B-cell neoplasms, including hairy cell leukemia (HCL), lack expression of the adhesion molecule leukocyte function antigen-1 (LFA-1/CD11a). Additionally, HCL cells express relatively low amounts of intercellular adhesion molecule-1 (ICAM-1/CD54) and may therefore be an inappropriate target for recognition by T cells or lymphokine-activated killer (LAK) cells. We tested whether these molecules were inducible on HCL cells and if induction would lead to enhanced susceptibility to lysis by LAK cells or cytolytic T cells. CD11a expression was induced by incubation with interferon-alpha (IFN-alpha) or interleukin-4. CD54 was induced by culturing the cells irrespectively of the addition of cytokines. Expression of CD11a and CD54 did not enhance susceptibility to either autologous or allogeneous LAK cells. However, induction of these adhesion molecules was accompanied by enhanced susceptibility to lysis by cytotoxic T lymphocyte clones. This lysis could be reversed by the addition of anti-CD11a and anti-CD54 antibodies. Finally, we monitored the expression of CD11a and CD54 on HCL cells from patients during IFN-alpha therapy. In one of four patients monitored, we observed rapid in vivo induction of CD11a and CD54 on the leukemic cells during IFN-alpha therapy. These studies provide a model for studying immunosurveillance in HCL.

Increased numbers of circulating haematopoietic progenitor cells after treatment with high-dose interleukin-2 in cancer patients.

Immunotherapy with recombinant interleukin-2 (IL-2) and lymphokine-activated killer (LAK) cells has been applied to patients with metastatic cancers for its antitumour activity. In the present study we investigated the effects of in vivo administration of IL-2 (3 x 10(6) U/m2/d, continuously i.v.) on haematopoiesis. Six patients with disseminated renal cell carcinoma, treated with IL-2 and LAK cells, were monitored for the numbers of white blood cells and circulating haematopoietic progenitor cells (HPC). During IL-2 treatment lymphopenia developed, followed by lymphocytosis after discontinuation of IL-2 infusions. IL-2 administration also resulted in neutrophilia and eosinophilia. Absolute numbers of circulating HPC declined markedly during IL-2 treatment. However, after completing IL-2 infusions, the numbers of circulating erythroid (BFU-E), myeloid (CFU-GM) and multipotential progenitor cells (CFU-GEMM) strongly increased, reaching a maximum after 5 d (day 10 from the start of IL-2 treatment). This increase did not result from repeated leucaphereses, since patients treated with IL-2 alone showed a similar response. In comparison with pretreatment levels the pool of circulating HPC expanded about 20-fold. This study illustrates that IL-2 treatment has a biphasic effect on the frequency of circulating BFU-E, CFU-GM and CFU-GEMM, causing a decrease during IL-2 infusion, followed by an increase after IL-2 administration. The total number of progenitor cells harvested by four consecutive leucaphereses is in the range that is commonly used for peripheral blood stem cell autografting.

Clonal B-cell populations in patients with idiopathic thrombocytopenic purpura.

Idiopathic thrombocytopenic purpura (ITP) may be associated with other autoimmune diseases and the development of lymphoproliferative malignancies. In Sjögren's disease, Graves' disease, and essential mixed cryoglobulinemia, which are also associated with the development of B-cell neoplasia, clonal B-cell expansions have been detected. Eleven patients with ITP were investigated for the presence of a clonal excess (CE) using kappa-lambda flow cytometry and DNA analysis for rearrangement of immunoglobulin heavy and light chain genes in blood and/or spleen lymphocytes. In 10 of 11 patients, clonal B-cell populations were found by one or both tests. In three of these patients, oligoclonal B-cell populations were suggested by the combined findings. In all four patients with a small paraproteinemia, the isotype was confirmed by either flow cytometry or DNA rearrangement analysis. Our data suggest that the oligoclonal expansions are not restricted to CD5+ B cells, as in the majority of patients this subset was below the detection level of flow cytometry or DNA rearrangement analysis. None of the patients developed clinical manifestations of malignant lymphoma during a follow-up period of 10 to 44 months after sampling. We conclude that clonal excess populations of B cells are not a unique feature of malignant lymphoma, but may occur in autoimmune diseases, suggesting a benign (oligo)clonal B-cell proliferation.

Lymphokine-activated killer cell functions in patients with leukemic B-lymphoproliferative diseases.

Nine patients with leukemic B-lymphoproliferative diseases (B-LPD) were evaluated for development of in vitro recombinant interleukin-2 (rIL-2)-activated killer (LAK) cells. B-cell cultures were established from peripheral blood mononuclear cells (PBMNCs) containing 63% +/- 29% malignant cells. Short-term cultures were tested after 5-day activation with 500 U rIL-2/mL. Long-term cultures were maintained for 4 to 6 weeks by weekly addition of 500 U rIL-2 and autologous irradiated feeder cells. In the first week, the cells decreased considerably in the long-term cultures but thereafter cells proliferated (mainly T cells) on the average 300-fold (range 30- to 1,000-fold). In the short-term cultures, there was a 36% reduction of malignant B cells. In long-term cultures, B cells were reduced from 63% to 8%; three cultures still contained greater than 15% B cells. The CD16-positive cell percentage was comparable in both types of cultures and ranged from 2% to 17%. Effector cells lysing the natural killer (NK)-sensitive cell line K562 could be induced in all patients. Except in patients with chronic lymphocytic leukemia (CLL) and high malignant cell numbers, NK activity was already restored after 5 days. Optimal NK activity was obtained after 1.5 to 2.5 weeks. LAK cells killing NK-resistant lymphoma cell lines showed optimal activity after 2 to 3 weeks of culture. However, LAK cells killing greater than 10% of autologous malignant cells were obtained in only one third of the patients. The discrepancy between strong cytolytic activity against the NK-sensitive (K562) target cells obtained in all patients and the cytotoxic activity against NK-resistant cell lines contrasts with the poor development of LAK cells against autologous tumor cells. This discrepancy does not appear to be explained by soluble inhibitory factors released during the tumor cultures, as allogeneic LAK cells were not inhibited by supernatants from patients' cultures. Further investigations are warranted to reveal cell-mediated inhibition by tumor cells or suppressor cells.