Interleukin-2 restores the depressed allogeneic cell-mediated lympholysis and natural killer cell activity in patients with systemic lupus erythematosus

Complement Factor H Family Proteins Modulate Monocyte and Neutrophil Granulocyte Functions

Besides being a key effector arm of innate immunity, a plethora of non-canonical functions of complement has recently been emerging. Factor H (FH), the main regulator of the alternative pathway of complement activation, has been reported to bind to various immune cells and regulate their functions, beyond its role in modulating complement activation. In this study we investigated the effect of FH, its alternative splice product FH-like protein 1 (FHL-1), the FH-related (FHR) proteins FHR-1 and FHR-5, and the recently developed artificial complement inhibitor mini-FH, on two key innate immune cells, monocytes and neutrophilic granulocytes. We found that, similar to FH, the other factor H family proteins FHL-1, FHR-1 and FHR-5, as well as the recombinant mini-FH, are able to bind to both monocytes and neutrophils. As a functional outcome, immobilized FH and FHR-1 inhibited PMA-induced NET formation, but increased the adherence and IL-8 production of neutrophils. FHL-1 increased only the adherence of the cells, while FHR-5 was ineffective in altering these functions. The adherence of monocytes was increased on FH, recombinant mini-FH and FHL-1 covered surfaces and, except for FHL-1, the same molecules also enhanced secretion of the inflammatory cytokines IL-1β and TNFα. When monocytes were stimulated with LPS in the presence of immobilized FH family proteins, FH, FHL-1 and mini-FH enhanced whereas FHR-1 and FHR-5 decreased the secretion of TNFα; FHL-1 and mini-FH also enhanced IL-10 release compared to the effect of LPS alone. Our results reveal heterogeneous effects of FH and FH family members on monocytes and neutrophils, altering key features involved in pathogen killing, and also demonstrate that FH-based complement inhibitors, such as mini-FH, may have effects beyond their function of inhibiting complement activation. Thus, our data provide new insight into the non-canonical functions of FH, FHL-1, FHR-1 and FHR-5 that might be exploited during protection against infections and in vaccine development.

Both perforin and FasL are required for optimal CD8 T cell control of autoreactive B cells and autoantibody production in parent-into-F1 lupus mice

To test the relative roles of perforin (pfp) vs. FasL in CTL control of autoreactive B cell expansion, we used the parent-into-F1 model of murine graft-vs.-host disease in which donor CD8 CTL prevent lupus like disease by eliminating activated autoreactive B cells. F1 mice receiving either pfp or FasL defective donor T cells exhibited an intermediate short-term phenotype. Pairing of purified normal CD4 T cells with either pfp or FasL defective CD8 T cell subsets resulted in impaired host B cell elimination and mild lupus like disease that was roughly equivalent in the two experimental groups. Thus, in addition to major roles in tumor and intracellular pathogen control, pfp mediated CD8 CTL killing plays a significant role in controlling autoreactive B cell expansion and lupus downregulation that is comparable to that mediated by FasL killing. Importantly, both pathways are required for optimal elimination of activated autoreactive B cells.

Defective in vitro IL-2 production in lupus is an early but secondary event paralleling disease activity: evidence from the murine parent-into-F1 model supports staging of IL-2 defects in human lupus

T cell defects are a well described feature of both human and murine lupus however their exact significance is unclear. Evidence from an induced model of lupus, the P --> F1 model of chronic lupus-like GVHD demonstrates that a secondary inducible T cell defect in in vitro IL-2 and CTL responses occurs early in the course of lupus-like disease and well in advance of clinical disease. Defective Th cell function was probed using a novel approach categorizing the response to two stimuli:1) the MHC self restricted response, termed self +X; and 2) the allogeneic response. Using this approach, lupus mice exhibited similar in vitro Th cell pattern i.e. an absent S+X response but preserved allogeneic (termed -/+). In contrast, human lupus patients exhibited three possible response patterns, +/+, - /+ or -/- with more severe in vitro T cell impairment correlated with more severe disease. Similarly, patients with other T cell mediated conditions i.e. HIV infection or renal allograft recipients, also exhibited more severe in vitro T cell impairment with greater disease activity or greater immunosuppression respectively. The similar Th response patterns in human and murine T cell mediated conditions indicates that the underlying mechanisms involved are not disease specific but instead reflect common immune responses and validate the use of the P --> F1 model for future studies of T cell mediated conditions. These results support the use of prospective monitoring of IL-2 responses in lupus patients. Successful adaptation of this approach to the clinical setting could allow not only earlier therapeutic intervention and reduced organ damage but also earlier tapering of pharmacological agents and reduced untoward effects.

Defective Control of Latent Epstein-Barr Virus Infection in Systemic Lupus Erythematosus

EBV infection is more common in patients with systemic lupus erythematosus (SLE) than in control subjects, suggesting that this virus plays an etiologic role in disease and/or that patients with lupus have impaired EBV-specific immune responses. In the current report we assessed immune responsiveness to EBV in patients with SLE and healthy controls, determining virus-specific T cell responses and EBV viral loads using whole blood recall assays, HLA-A2 tetramers, and real-time quantitative PCR. Patients with SLE had an approximately 40-fold increase in EBV viral loads compared with controls, a finding not explained by disease activity or immunosuppressive medications. The frequency of EBV-specific CD69+ CD4+ T cells producing IFN-gamma was higher in patients with SLE than in controls. By contrast, the frequency of EBV-specific CD69+ CD8+ T cells producing IFN-gamma in patients with SLE appeared lower than that in healthy controls, although this difference was not statistically significant. These findings suggest a role for CD4+ T cells in controlling, and a possible defect in CD8+ T cells in regulating, increased viral loads in lupus. These ideas were supported by correlations between viral loads and EBV-specific T cell responses in lupus patients. EBV viral loads were inversely correlated with the frequency of EBV-specific CD69+ CD4+ T cells producing IFN-gamma and were positively correlated with the frequencies of CD69+ CD8+ T cells producing IFN-gamma and with EBV-specific, HLA-A2 tetramer-positive CD8+ T cells. These results demonstrate that patients with SLE have defective control of latent EBV infection that probably stems from altered T cell responses against EBV.

Infectious complications in SLE after immunosuppressive therapies

Immunosuppressive drugs have become the gold standard for the treatment of major organ involvement in systemic lupus erythematosus. The use of immunosuppressive therapy in systemic lupus erythematosus carries significant risks for infection. This article reviews infectious complications in systemic lupus erythematosus, focusing on effects of immunosuppressive therapy. Patients with systemic lupus erythematosus appear to carry an intrinsically increased risk for infection. Recent studies support this notion further by showing increased risk for serious infections in patients with systemic lupus erythematosus who had mannose-binding lectin deficiency associated with homozygous mannose-binding lectin variant alleles. Patients with systemic lupus erythematosus who were homozygous for mannose-binding lectin variant alleles had a fourfold increase in the incidence of infections, requiring hospitalization. In terms of extrinsic risk factors for infection, use of steroids and cyclophosphamide are the strongest risk factors. The effect of these drugs on infection is also dose dependent. The incidence of infectious complications in patients treated with mycophenolate mofetil, a newly used immunosuppressive drug in systemic lupus erythematosus, appears less frequent compared with cyclophosphamide. Herpes zoster is still the most common viral infection in patients with systemic lupus erythematosus treated with cyclophosphamide and mycophenolate mofetil. Overall data indicate that patients with systemic lupus erythematosus may have intrinsically increased risks for infection that are augmented by immunosuppressive therapies. Cyclophosphamide, in particular in combination with high-dose glucocorticoids, has the strongest effect in suppressing the immune responses against microorganisms. Careful monitoring of infectious complications is warranted in patients with systemic lupus erythematosus receiving immunosuppressive therapies, in particular those on high-dose glucocorticoids and cytotoxic drugs.

Impaired recovery and cytolytic function of CD56+ T and non-T cells in systemic lupus erythematosus following in vitro polyclonal T cell stimulation. Studies in unselected patients and monozygotic disease-discordant twins

OBJECTIVE

To determine whether there is impaired generation and cytolytic function of CD56+ T cells and non-T cells in human systemic lupus erythematosus (SLE).

METHODS

Peripheral blood mononuclear cells (PBMC) were obtained from 73 patients with SLE, 39 normal controls, and 9 pairs of monozygotic (MZ) twins discordant for SLE. PBMC were stimulated with anti-CD3 monoclonal antibody, maintained in interleukin-2, and assayed for percentages of total CD56+ cells and CD56+ T cells by flow cytometry, and for cytolytic activity against 51Cr-labeled Daudi target cells.

RESULTS

Despite normal total cell expansion, the percentages of recovered CD56+ T cells and total CD56+ cells were 1.6-fold and 1.8-fold lower, respectively, in patients with SLE compared with normal controls (P = 0.011 and P < 0.001, respectively). Cytolytic activities of isolated total CD56+ cells and CD56+ T cells and were also reduced in patients with SLE compared with normal controls (P = 0.033). These defects associated with SLE were independent of disease activity and immunosuppressive medications, and they reflected impaired maturation of cytolytic effector cells rather than a deficiency in precursor cell number. In MZ twins discordant for SLE, recovered percentages of CD56+ cells and cytolytic responses were very low in 4 of 8 and 6 of 9 co-twins with SLE, respectively. Cellmixing experiments with the PBMC of the MZ twins demonstrated that the E+ cell fractions (containing all T cells and CD56+ non-T cells) from the co-twins with SLE had decreased ability to generate cytolytic activity compared with the corresponding E+ cell fractions from the healthy co-twins. However, recovered percentages of CD56+ cells and non-T cells and cytolytic responses were also depressed in 4 of 8 and 4 of 9 healthy co-twins, respectively.

CONCLUSION

Impaired CD56+ T cell and non-T cell responses are a feature of SLE and may antedate the onset of clinical disease.

Okadaic acid-like toxin in systemic lupus erythematosus patients: hypothesis for toxin-induced pathology, immune dysregulation, and transactivation of herpesviruses

Preliminary evidence suggests there is a toxin in the sera of systemic lupus erythematosus patients which reacts with a commercial enzyme-linked immunosorbent assay kit for the detection of the marine toxin, okadaic acid. Data is presented which supports the hypothesis that an okadaic acid-like toxin may be the principle agent of lymphocyte dysregulation in systemic lupus erythematosus and other immune-dysregulated states. The okadaic acid-like toxin can produce the specific abnormalities in T-lymphocyte phenotype and function typical of systemic lupus erythematosus, principally through its ability to inhibit serine/threonine phosphatases necessary for secondary signalling processes and through its ability to inhibit calcium which is crucial to protein kinase C-mediated signalling of T-lymphocytes. The disruption probably occurs through the protein tyrosine kinase p56lck pathway crucial for IL-2. Additionally, the toxin's ability to disrupt voltage-sensitive ion channels in cell membranes may be responsible for the multi-organ pathology observed in systemic lupus erythematosus patients, particularly neurological, cardiac and nephritic. Data from a different study conducted by the author suggests that latent and persistent viruses are reactivated in active lupus. This activation could be the result of the toxin's ability to act as an immune modulator, or its ability to act as a transactivating factor.

Impaired generation of polyclonal T cell-mediated cytolytic activity despite normal polyclonal T cell proliferation in systemic lupus erythematosus

No differences in proliferation induced by the anti-CD3 MAb 454 were detected between systemic lupus erythematosus (SLE) and normal peripheral blood mononuclear cells (PBMC) or purified T cells. In contrast, overnight culture with soluble MAb 454, immobilized MAb 454, or rIL2 induced significantly less increase in cytolytic activity against Daudi targets in SLE PBMC than in normal PBMC. Cytolytic activity in SLE PBMC cultures sequentially stimulated with soluble MAb 454 and rIL2 over a 6-day period overall was also lower than normal (with approximately 50% of the individual SLE cultures generating clearly subnormal levels of cytolytic activity) and did not correlate with the daily corticosteroid dose or with the presence of nephritis. Phenotypic analysis of soluble MAb 454-stimulated SLE PBMC cultures maintained for up to 23 days in rIL2 indicated that greater than 90% (and often greater than 96%) of the recovered cells were CD3+. Cytolytic activity generated in cultures of purified T cells stimulated with soluble MAb 454 + rIL2 over a 6-day period was also subnormal in 4/8 SLE donors, suggesting that the impaired generation of cytolytic activity in SLE is caused, at least in part, by impaired T cell-mediated cytolytic activity. Taken together, these observations demonstrate that normal CD3/T cell antigen receptor (TCR)-triggered polyclonal T cell proliferation can be dissociated from abnormal CD3/TCR-triggered polyclonal T cell cytolytic activity in SLE. This may have important implications for the pathogenesis of SLE and/or for the immunocompromised state seen in SLE.

Enhancement of human T lymphocyte function by prothymosin alpha: increased production of interleukin-2 and expression of interleukin-2 receptors in normal human peripheral blood T lymphocytes

The in vitro incubation of phytohemagglutinin (PHA)- or alloantigen-stimulated peripheral blood T cells with prothymosin alpha (ProT alpha) resulted in a marked and reproducible increase in the production of interleukin-2 (IL-2). Incubation of T cells with ProT alpha, in the absence of PHA or alloantigen, failed to induce any production of IL-2. ProT alpha by itself did not exert any IL-2 activity. Finally, ProT alpha was shown to increase the expression of IL-2 receptors on phytohemagglutinin- or alloantigen-activated T cells. These data provide the basis for understanding the in vitro immunoenhancing effects of ProT alpha in cellular immune systems.

Natural killer cells and autoimmunity

In various autoimmune diseases it appears that NK activity is impaired, and that this phenomenon is significant in disease development. Impairment of NK activity may be the result of two different mechanisms. In systemic autoimmune diseases, in which various target organs are involved (nonorgan-specific), the peripheral blood NK level is generally lower than normal. This most likely allows the expression of autoimmune phenomena such as B cell hyperactivity and polyclonal antibody production, as is seen in SLE, due to a defect in the termination of the immune response. In autoimmune diseases with more localized, organ-specific lesions one can detect increased NK activity at the target organ itself. In these instances, the cytotoxic characteristic of the NK cell is more prominent. This theory explains why both increased and decreased NK activity may be observed in autoimmune diseases. In some disorders in which decreased NK activity was suspected of being crucial, immunomodulators, known to increase NK activity, were administered. Yet it is still difficult to separate the NK activity from the effect of the remaining immune system.

Deficient interleukin-2-activated killer cell cytotoxicity in patients with systemic lupus erythematosus

This study was undertaken to determine if the cytotoxic activity of interleukin-2 (IL-2)-activated killer (LAK) cells, which is induced by the direct activation of lymphocytes by IL-2, is defective in systemic lupus erythematosus (SLE). The killer cell activity of SLE patients, whether it be generated in autologous plasma or serum-free media, was significantly less than the controls against three different target cells. It was observed, by incubating control lymphocytes in 10% fresh SLE plasma, that soluble factors were responsible for a portion of the reduced generation of LAK cell cytotoxicity (P less than 0.05). Suppression ranges from 4 to 70% with a mean of 33%. However, when SLE LAK cells were generated in serum-free media, a greater reduction of generated LAK cell activity was observed (P less than 0.005). Using a disease activity score, it was determined that SLE cytotoxicity negatively correlated with disease activity only when the cells were cultured in serum-free media. Irrespective of the culture conditions, lytic activity did not correlate with levels of anti-DNA antibodies, anti-Sm antibodies, circulating immune complexes, or prednisone therapy.

Role of interleukin 2 in inducing normalization of natural killer activity in systemic lupus erythematosus

A low natural killer (NK) activity has been well documented for lymphocytes from systemic lupus erythematosus (SLE) patients. Given the defect in interferon-gamma (IFN-gamma) and interleukin 2 (IL-2) production also reported in SLE, it seemed possible that the absence of these molecules could account for some of the defective NK activity. We have tested the NK activity present in peripheral blood mononuclear cells (PBMC) from SLE patients and its in vitro modulation by different preparations of exogenous IL-2. We have found a low NK activity for PBMC from steroid-treated SLE patients, and we report an enhancement in lytic activity after incubation with mitogen-induced, IL-2-containing supernatants obtained from human tonsils. This increase did not seem to be due to recruitment of new effectors because the numbers of cells expressing NK phenotype (Leu 7+ or Leu 11b+) did not change after the incubation, nor did the target specificity of the lysis. However, a similar degree in the improvement in cytotoxicity was not obtained by incubation with a purified preparation of IFN gamma and/or recombinant IL-2 (rIL-2). A possible role for a molecule other than these lymphokines that might influence this effect is discussed.

Increased serum levels of soluble interleukin-2 receptor in patients with systemic lupus erythematosus and rheumatoid arthritis

In this study we investigated the serum levels of a released soluble form of the interleukin-2 receptor (sIL-2R) in 42 patients with rheumatoid arthritis and in 12 cases of systemic lupus erythematosus. Data were evaluated in relationship to the clinical phase and compared with those observed in normal controls (N = 56) and in osteoarthritis (N = 7). Increased levels were observed in both rheumatoid arthritis (mean +/- SE, 604 +/- 49 U/ml) and systemic lupus erythematosus (1438 +/- 481 U/ml). These values were significantly higher than in control (256 +/- 15 U/ml; P less than 0.001) and in osteoarthritis (298 +/- 33 U/ml; P less than 0.001) groups. In addition, the highest values were associated with the active phases of both rheumatoid arthritis (active vs inactive, 771 +/- 78 vs 451 +/- 39 U/ml; P less than 0.001) and systemic lupus erythematosus (active vs inactive, 2108 +/- 489 vs 499 +/- 75 U/ml; P less than 0.001). Our findings suggest that the detection of sIL-2R in rheumatoid arthritis and in systemic lupus erythematosus may represent a good marker of disease activity, which indirectly indicates the ongoing activation and/or proliferation of immunoreactive cells which are involved in the pathogenetic events of these autoimmune conditions.

Mechanism of action of prothymosin alpha in the human autologous mixed lymphocyte response

Prothymosin alpha(Prot alpha), an immunologically active polypeptide derived initially from rat thymus, and now pig thymus, was tested for its effect on autoantigen-induced human T cell proliferation in vitro. Pig ProT alpha was found to enhance the autologous mixed lymphocyte response (auto-MLR). Optimum enhancement was achieved at doses which varied among different donors. Treatment of the stimulatory monocytes with ProT alpha resulted in considerably higher auto-MLR responses as compared to those with non treated monocytes. ProT alpha was without effect on T lymphocytes. In contrast, T lymphocytes exhibited enhanced proliferative activity when treated with ProT alpha in the environment of autologous monocytes. Moreover, supernatants from cultures of monocytes incubated with ProT alpha (ProT alpha-sup) were also shown to enhance the human auto-MLR either after addition in cultures or after preincubation with responder T lymphocytes. In addition, ProT alpha-sup did not demonstrate any detectable interleukin 1 (IL 1) or interleukin 2 (IL 2) - like activity. Furthermore, ProT alpha-sup induced an increase in IL 2 production in auto-MLR cultures. The enhancement of T-cell proliferation and IL 2 production by ProT alpha-sup was maximal when this material was added at the beginning of the auto-MLR, and no effect of ProT alpha-sup was seen if the latter was added 3 days after initiation of the culture. Finally, Prot alpha-sup was also shown to increase the expression of IL 2 receptors on T lymphocytes activated in the auto-MLR. These studies suggest that ProT alpha enhances the human auto-MLR through ProT alpha-sup which is released after interaction of monocytes with ProT alpha ProT alpha-sup then increases directly T lymphocyte proliferation by elevating IL 2 production and expression of IL 2 specific receptors on autoactivated T lymphocytes.

Deficient gamma-interferon production in patients with systemic lupus erythematosus

We examined the ability of peripheral mononuclear cells (MNC) from patients with systemic lupus erythematosus (SLE) to produce gamma-interferon (gamma-IFN) in vitro. MNC from patients with SLE produced varying amounts of gamma-IFN upon mitogenic stimulation. However, they produced distinctly decreased amounts of gamma-IFN upon in vitro stimulation with interleukin-2 (IL-2). Deficient production seemed to be primary, rather than secondary to either excessive monocytic suppression or failure of IL-2 to bind to the MNC surface membranes. gamma-IFN-specific RNA transcription, as determined by slot-blot analysis, was severely decreased in MNC that had been stimulated with phytohemagglutinin or IL-2. These findings suggest that MNC of patients with SLE have defects in the IL-2 signal transduction which is required for production of gamma-IFN.

Peripheral blood natural killer cell activity in human breast cancer patients and its modulation by T-cell growth factor and autologous plasma

The role of clinical status and chemotherapeutic intervention on native and inducible natural killer cell (NK) activity in breast cancer was ascertained by determining the K562 cytotoxicity capacity of peripheral blood lymphocytes. The level of NK activity in breast cancer patients receiving chemotherapy (n = 62) was significantly lower than that observed in patients currently receiving no treatment (n = 56) (at effector: target [E:T] ratios of 20:1, 10:1, and 5:1, 23.8%, 17.9%, and 12.1% versus 34.9%, 25.6%, and 15.9%, respectively; P less than 0.01, two-way analysis of variance). The absolute level of NK activity in peripheral blood of cancer patients on therapy was further reduced when compared with untreated patients and healthy controls when reductions in lymphocyte counts concomitant with chemotherapeutic intervention were included in calculations of NK activity. T-cell growth factor (TCGF) increased NK activity in all breast cancer patients and healthy controls with maximal stimulation of basal activity at a concentration of 10% (volume/volume [v/v]) TCGF. The percent stimulation of basal NK activity by TCGF was significantly greater in patients receiving chemotherapy (26.4%, 24.3%, and 19.0% at an E:T of 20:1, 10:1, and 5:1, respectively; n = 23) than in untreated patients (16.6%, 18.5%, and 18.9%; n = 21) and healthy controls (23.5, 18.6, and 8.1; n = 8) (P less than 0.05 and P less than 0.01, respectively, two-way ANOVA). The influence of soluble factors and agents in serum on peripheral blood NK activity was assessed by monitoring the effects of autologous plasma on basal and TCGF-stimulated NK activity. Autologous plasma at concentrations less than or equal to 10% (v/v) enhanced basal NK activity. Levels of inducible NK activity in the presence of either 10% TCGF, 5% plasma, or a combination of both were not significantly different in statistical comparisons of both the effects of inducer and therapeutic modality. At concentrations of plasma greater than 10% (v/v), progressively decreasing NK activities were observed. T-cell growth factor could partially reverse the inhibitions of NK activity by 25% autologous plasma. In 13 experiments, basal NK activity and NK activity in the presence of 10% TCGF, 25% autologous plasma, and a combination of TCGF and plasma were 27.6%, 46.0%, 16.3%, and 28.1%, respectively (E:T = 20:1). This study indicates that NK function is compromised in breast cancer patients receiving cytotoxic drug-therapy. The potential use of TCGF in adjuvant immunotherapy as a modulator of NK function has been demonstrated.(ABSTRACT TRUNCATED AT 400 WORDS)

Lack of natural killer cell activity in hairy cell leukemia patients and partial restoration with interleukin-2

Natural Killer (NK) cell activity was studied in ten hairy cell leukemia (HCL) patients by means of a 4-hour cytotoxicity assay using mononuclear cells isolated from either the spleen or peripheral blood. Identical assays were performed on individuals who were either normal or had nonmalignant hematologic disorders. HCL patients had a significant decrease in NK cell activity at all effector-to-target ratios compared with the control group. Effects of interleukin-2 (IL-2) on NK activity were studied in four patients. After a 3-day in vitro incubation with IL-2, there was a marked increase in NK activity of mononuclear cells obtained from each of these patients. On the basis of the results it can be hypothesized that susceptibility to infections, which are commonly encountered in HCL patients, may be due in part to a low level of NK activity. Based on the apparent augmentation of NK activity in vitro, it might be of interest to initiate a clinical trial with IL-2 in patients with HCL.