Defective interleukin 2 receptor expression is associated with the T cell disfunction subsequent to bone marrow transplantation

Differing functional recovery of donor-derived immune cells after purified haploidentical and fully mismatched hematopoietic stem cell transplantation in mice

Functional recovery of the immune system is critical for long-term survival in hematopoietic stem cell transplant recipients. In this study, two donor-recipient allogeneic transplant settings (haploidentical and fully mismatched) are used to investigate the functional activity of donor-derived B and T cells in animals grafted with purified c-kit(+), Thy 1.1(lo), Lin(-/lo), and Sca-1(+) hematopoietic stem cells (KTLS HSC).Ovalbumin-specific immunoglobulin G, polyclonal immunoglobulin isotypes, and B- and T-cell proliferation were examined on the recipients who received haploidentical or fully mismatched HSC.A severe deficiency of antigen-specific immunoglobulin response occurs in fully engrafted mice that received KTLS HSC from fully mismatched, but not haploidentical, donors. This lack of B-cell-specific immunity is not due to a deficiency of polyclonal immunoglobulins in serum. B cells from both fully mismatched and haploidentical recipients proliferate normally after stimulation with anti-mu and the percentage of mature B cells is normal. The T-cell response to anti-CD3 in fully mismatched recipients was much weaker than that of their untransplanted controls. However, T cells from haploidentical recipients respond normally to anti-CD3. This study demonstrates that numerical recovery of donor-derived cells in the periphery of recipients does not represent a functional reconstitution, particularly in animals that receive fully mismatched transplants. Defects of specific B-cell immunity and T-cell proliferation are observed in fully mismatched, purified HSC transplant recipients with a quantitative recovery within the normal range of donor-derived lymphocytes.

Secretion of IL-2, IL-3, IL-4, IL-6 and GM-CSF by CD4+ and CD8+ TCR alpha beta+ T-cell clones derived early after allogeneic bone marrow transplantation

Secretion of different cytokines may be an important T-cell effector mechanism for bone marrow engraftment, graft versus host disease and graft versus leukaemia effects after allogeneic bone marrow transplantation (BMT). Cytokine secretion and autocrine proliferative capacity of T-cell clones derived from leukaemia patients 3-6 weeks after allogeneic bone marrow transplantation were investigated. Only a minority of post-transplant T-cell clones (23/120; 19%) was capable of undergoing autocrine proliferation. By contrast, 21/65 (32%) normal control clones from the marrow donors derived under the same conditions were autocrine proliferative. All clones were interleukin-2 (IL-2) responsive. A majority (12/17; 71%) of autocrine proliferating post-transplant clones secreted detectable IL-2. Compared with control clones, CD4+ T-cell clones derived early after BMT produced decreased levels of interleukin-4 (IL-4) and interleukin-6 (IL-6), whereas secretion of interleukin-3 (IL-3) and granulocyte/macrophage colony-stimulating factor (GM-CSF) showed no significant difference. The small number (n = 8) of posttransplant CD8+ clones showed decreased production of IL-3, IL-4 and IL-6 compared with control clones, but normal secretion of GM-CSF. Neither CD4+ nor CD8+ T-cell clones secreted interleukin-7 (IL-7).

Analysis of different protein kinase C-dependent events in T cells from allogeneic bone marrow transplantation recipients

In order to understand the mechanisms underlying the T lymphocyte dysfunction associated to allogeneic bone marrow transplantation (BMT), we assessed two different protein kinase C (PKC) dependent events in T cells from BMT recipients: the PKC-dependent membrane expression and function of the CD69 early activation antigen; and the rapid phorbol ester-induced phosphorylation of PKC protein substrates in lysates from T cells permeabilized with digitonin, in the presence of (gamma-32P)ATP. Most BMT recipient T cells detectably expressed the CD69 surface antigen after 24 h of stimulation with either phorbol 12-myristate 13-acetate (PMA) or anti-CD3 MoAb and PMA, thus indicating that PKC activity is sufficient to induce de novo gene expression. Nevertheless, it is noteworthy that the fluorescent staining intensity with anti-CD69 MoAbs was significantly lower in BMT recipient T cells than in normal T lymphocytes, although no clear-cut correlation was found between the expression of CD69 and the proliferative capacity. However, the pattern of PMA-induced phosphoproteins analysed as early as 1 min after PKC activation in T cells from BMT recipients displaying a low response to mitogenic stimuli, was undistinguishable from that detected in T cells from healthy subjects. In all cases a major 110-kD phosphoprotein was observed, which was inducible with PMA, phorbol 12,13-dibutyrate (PDBu), 1-oleoyl-2-acetylglycerol (OAG) and a phorbol-ester-related activator of PKC (mezerein); moreover, its phosphorylation was blocked by pretreating cells with the PKC inhibitor H-7. Altogether our results suggest that the depressed mitogenic responses, which were also observed in the present study when T cells were stimulated via CD69, cannot be simply attributed to a defective PKC activity.

Relation between the increase of circulating CD3+ CD57+ lymphocytes and T cell dysfunction in recipients of bone marrow transplantation

Some patients undergoing bone marrow transplantation (BMT) persistently present increased proportions of circulating CD57+ T cells. We analysed the cell surface phenotype in peripheral blood mononuclear cells (PBMC) from 69 allogeneic and 11 autologous BMT recipients. In parallel samples from 49 patients, the proliferative response to T cell mitogens was assessed, either in the presence or absence of exogenous interleukin-2 (IL-2). PBMC samples from long-term allogeneic BMT patients with increased proportions of CD57+ cells displayed significantly (P less than 0.001) lower proliferative responses, compared with samples from patients with normal proportions of CD57+ cells and from healthy subjects. Elimination of the CD57+ population by C'-dependent lysis did not normalize the proliferative response. After positive selection by cell sorting, CD57+ cells responded poorly, but in the presence of IL-2 the proliferation appeared to be similar to that displayed by the CD57- subset and still suboptimal compared with normal controls. These data suggest that the hyporesponsiveness to mitogenic stimuli in the presence of exogenous IL-2 of PBMC from allogeneic BMT recipients cannot be simply attributed either to the putative suppressor activity of CD57+ cells, or to a poor proliferative capacity of this subset. Supporting this notion we report that PBMC from long-term autologous BMT recipients containing high proportions of CD57+ T cells respond normally to T cell mitogens.

Immunodeficiency after allogeneic bone marrow transplantation in man. Effect of phorbol ester (phorbol myristate acetate) and calcium ionophore (A23187) in vitro

This study was undertaken to clarify the mechanism behind the severely decreased lymphocyte proliferative response upon stimulation with mitogens and antigens seen after allogeneic bone marrow transplantation (BMT) in man. We investigated eight BMT patients and eight controls and found that the proliferative response of patient cells was reduced both when the cells were stimulated with phytohaemagglutinin (PHA) and when they were stimulated with a combination of phorbol myristate acetate (PMA), which is an activator of protein kinase C (PKC), and the calcium ionophore A23187, which irreversibly opens for calcium transport into the cell (median relative responses were 41 and 37%, respectively). However, the PHA-induced increase in the concentration of intracellular free calcium in post-BMT cells was not significantly different from the values found in control cells and the expression of interleukin 2 (IL-2) receptors (CD25) was only slightly decreased. However, the production of IL-2 was severely decreased in patient cells after stimulation with A23187/PMA (median 3541 units), although it was higher than in PHA-stimulated control cells (median 354 units). These results show that a direct activation of PKC by PMA combined with an increase in intracellular free calcium by A23187 cannot overcome the lymphocyte proliferation deficiency in cells from patients after allogeneic BMT. The data suggests that the defect is affecting the diacylglycerol pathway considerably more than the inositol triphosphate pathway.

A phase-II study of adoptive immunotherapy with continuous infusion of interleukin-2 in children with advanced neuroblastoma. A report on 11 cases

Nine children with poor prognosis neuroblastoma have been treated by continuous infusion of IL-2 and autologous LAK cells, as described previously by West et al. in adult patients. Six patients were in relapse after high-dose chemotherapy and autologous BMT and three presented with primary refractory disease after conventional therapy. Although patients were very young (median age 6 years; average weight 17 kg), infusion of IL-2, cytapheresis and reinjection of LAK cells appeared feasible with the usual and transient complications observed with IL-2. Haematological toxicity, although reversible, was more important than usually described and due to the presence of bone-marrow metastases in 8 of the 9 patients. Life-threatening toxicity was observed in only one of the admission centres and was probably due to the rapid reinjection of a very large number of activated cells. Two patients presenting with very active disease after high-dose chemotherapy and autologous or allogeneic BMT received IL-2 alone, at 120 days and at 90 days after the graft. The reactivation of grade-II GVHD was the major complication in the patient treated after an allograft, whereas no BMT-related toxicity was observed in the patient treated after the autologous BMT. Immunological modifications induced by IL-2 were very different between these patients. As expected, a preferential outgrowth of NK cells with both NK and LAK activity was observed in the patient treated just after the autograft. In contrast, in the patient treated after an allograft and in the 9 patients in relapse, T lymphocytes remained the major mononuclear cell population with a very large excess of CD8+ T cells. All patients progressed after the first induction cycle with the exception of the only patient treated after autologous BMT who reached a very good partial remission with disappearance of the local tumor and bone metastases. Although very preliminary, these data clearly show that the efficacy of IL-2 largely depends on the patient's immunological status with the optimal effect being observed when IL-2 is given in the first few months following an autograft.

High toxic efficiency of ricin immunotoxins specific for the T-cell antigen receptor of a human leukemia T-cell line

Immunotoxins (ITs) were prepared by covalently coupling ricin to monoclonal antibodies (MAbs) directed against: (a) 2 different epitopes of the T-cell receptor (TcR) expressed by the Jurkat leukemia T-cell line (JTi2 and JTi4 MAb), (b) 2 epitopes of the CD3 complex (SpV-T3b and 11D8 MAb), (c) the CD2 and the CD8 cell-surface molecules. Conjugates were assayed for their cytotoxic activity by pre-incubating the Jurkat cell line with different concentrations (10-250 ng/ml) of each IT for 2 hr at 37 degrees C in the presence of 0.1 M lactose. After washing, cells were cultured for 24 hr and their protein synthesis and proliferative capacities were assessed. Dose-response experiments indicated that JTi2, JTi4 and anti-CD3 (11D8) ITs inhibited by greater than 90% the cell line proliferation at 50 ng/ml, a 5-fold lower concentration than that required to achieve a similar effect when anti-CD2 and anti-CD3 (SpVT3b) were used. After 4 hr of culture subsequent to treatment with JTi2 or JTi4 ITs (250 ng/ml), protein synthesis was inhibited (greater than 80%). By limiting dilution analysis (LDA) we estimated that the frequency of proliferating Jurkat cells (1/1.5) was reduced to 1/20, 1/460 and 1/300 after treatment with anti-CD3 (SpVT3b), JTi4 and JTi2 ITs, respectively. Phenotypic analysis of 13 clones derived from JTi2 IT-treated Jurkat cells showed that 50% were CD7+ CD3- JTi- variants. When bone-marrow mononuclear cells, previously mixed with low concentrations of Jurkat cells, were treated with anti-JTi ITs, the toxic efficiency estimated by LDA was maintained whereas the growth of CFU-GM remained unaltered.