T helper cell dysfunction in systemic lupus erythematosus (SLE): relation to disease activity

Expression of Th1/Th2 cytokine mRNA in peritoneal exudative polymorphonuclear neutrophils and their effects on mononuclear cell Th1/Th2 cytokine production in MRL-lpr/lpr mice

Peritoneal exudative polymorphonuclear neutrophils (PEC-PMN) and mononuclear cells (PEC-MNC) were obtained from normal BALB/c and from autoimmune MRL-lpr/lpr mice (lpr) with different disease severities. The spontaneous and mitogen-stimulated expression of T-helper lymphocyte type-1 (Th1) [represented by interferon-gamma (IFN-gamma) and interleukin (IL-2)] and T-helper lymphocyte type-2 (Th2) (represented by IL-4 and IL-10) cytokine mRNA in these cells was detected by reverse transcription-polymerase chain reaction (RT-PCR). The production of these cytokines was measured by enzyme-linked immunosorbent assay (ELISA). We found that the spontaneous expression of Th1/Th2 cytokine mRNA in PEC-PMN from autoimmune mice was progressively increased in parallel with disease severity but was not changed by lipopolysaccharide (LPS) stimulation. By contrast, spontaneous expression of Th1/Th2 cytokine mRNA in PEC-MNC from these mice was progressively decreased in parallel with disease severity but retained the responsiveness to phytohaemagglutinin (PHA) stimulation. To determine the effect of PEC-PMN on Th1/Th2 cytokine production by PEC-MNC, autologous PEC-PMN and PEC-MNC were co-cultured at MNC:PMN ratios of 5:0, 4:1, 3:2, 2:3, 1:4 and 0:5 with PHA stimulation for 24 hr. The production of cytokines at each ratio was compared with the expected value, by calculation. We found that PEC-PMN from autoimmune mice progressively suppressed the production of IL-4, IL-10 and IFN-gamma whereas the production of IL-2 was enhanced by autologous MNC in parallel with disease severity. These results suggest that a reciprocal relationship exists in the expression of Th1/Th2 cytokine mRNA between PEC-PMN and PEC-MNC in lpr mice in parallel with disease severity. Autoimmune PEC-PMN can exert significant modulatory effects on Th1/Th2 cytokine production by autologous MNC in stimulation.

Decreased Th1-like and increased Th2-like cells in systemic lupus erythematosus

The proportion of the lymphocytes which produce the cytokines corresponding to murine T helper- (Th1) or Th2 cells was studied using flow cytometry in systemic lupus erythematosus (SLE). When the peripheral mononuclear cells were stimulated with phorbol myristate acetate and ionomycin in the presence of monensin, which blocks the secretion of cytokines, the positive rates for the cytoplasmic IL-2 and IFN-gamma were lower and those for the cytoplasmic IL-4 and IL-10 were higher in SLE than in normal subjects. When the cells were cultured with monensin alone, the positive rates for these 4 cytokines were slightly increased in SLE. These data suggest that the mononuclear cells are already activated in vivo and a deviation of the proportion of the Th cells to the Th2-like ones might be associated with the polyclonal B cell activation seen in SLE.

Infection in systemic lupus erythematosus

The improved survival of SLE patients since the 1950s is the result of not only better treatment, but also supportive treatment of renal failure and the wealth of antibiotics now available. Ironically, the wider use of immunosuppressives, especially the alkylating drugs, and the longer survival of patients with renal insufficiency and renal failure have made the identification and appropriate treatment of infection in SLE an ongoing challenge.

Proliferative responses to recall antigens are associated with pregnancy outcome in women with a history of recurrent spontaneous abortion

Maternal tolerance of the fetal hemiallograft suggests that immunomodulation occurs during gestation. Therefore, recurrent spontaneous abortion (RSA) may represent a failure of the immune changes that maintain pregnancy. We hypothesized that fertile women but not women with RSA may lose their immune responses to recall antigens when pregnant. This phenomenon has been seen in immunosuppressed transplant recipients and is associated with graft survival. Therefore, we evaluated proliferative responses to recall antigens in four groups of women: group 1, nonpregnant fertile women with no history of pregnancy loss and at least one prior healthy pregnancy, n = 13; group 2, nonpregnant women with a history of three or more spontaneous abortions, n = 28; group 3, healthy pregnant women between 6 and 9 wk of gestation without a history of prior pregnancy loss, n = 15; and group 4, pregnant women between 6 and 9 wk of gestation, with a history of RSA, n = 22. Proliferative responses of peripheral blood leukocytes to the recall antigens influenza and tetanus, alloantigens, and phytohemagglutinin were determined prospectively. Positive responses (stimulation index > 3) to recall antigens (a response to either influenza or tetanus was considered positive) were as follows: group 1 (nonpregnant fertile women), 11/13 (85%); group 2 (nonpregnant RSA women), 24/28 (86%); group 3 (pregnant fertile women), 4/15 (27%) (P </= 0.007); and group 4 (pregnant RSA women), 13/22 (59%) (P = 0.032) [corrected]. In group 4, there was 100% fetal survival in the nine women who lost responsiveness to recall antigens; however, in the 13/22 patients who responded to recall antigens, 9/13 (69%) had a repeat spontaneous abortion. These findings suggest that immunosuppression, indirectly measured by proliferation to recall antigens, is necessary for early pregnancy maintenance. Furthermore, this approach may be useful for predicting pregnancy outcome for women with RSA and may provide a useful means for designing and monitoring therapies.

Modulation of T-helper cell populations: potential mechanisms of respiratory hypersensitivity and immune suppression

Information presented at this symposium indicates that modulation of Th cell responses is one means by which xenobiotics may cause immunotoxicity. A shift from Th1 to Th2 responses can enhance both infectious and allergic disease. Hence, in some cases, a common mechanism may be responsible for effects that are generally considered to be very different. Because cytokines produced in the inflammatory process play a role in modulation of Th cell responses, there is a mechanism by which agents that appear to have only local effects at the portal of entry may, in fact, affect immune responses systemically. An understanding of conditions which trigger certain cytokine responses may be useful not only in understanding inflammation but also in predicting certain kinds of immunosuppressive and allergic responses. Future studies in this area are likely to provide insights into many areas of immunotoxicology.

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.

Type 1 and type 2 cytokine dysregulation in human infectious, neoplastic, and inflammatory diseases

In the mid-1980s, Mosmann, Coffman, and their colleagues discovered that murine CD4+ helper T-cell clones could be distinguished by the cytokines they synthesized. The isolation of human Th1 and Th2 clones by Romagnani and coworkers in the early 1990s has led to a large number of reports on the effects of Th1 and Th2 on the human immune system. More recently, cells other than CD4+ T cells, including CD8+ T cells, monocytes, NK cells, B cells, eosinophils, mast cells, basophils, and other cells, have been shown to be capable of producing "Th1" and "Th2" cytokines. In this review, we examine the literature on human diseases, using the nomenclature of type 1 (Th1-like) and type 2 (Th2-like) cytokines, which includes all cell types producing these cytokines rather than only CD4+ T cells. Type 1 cytokines include interleukin-2 (IL-2), gamma interferon, IL-12 and tumor necrosis factor beta, while type 2 cytokines include IL-4, IL-5, IL-6, IL-10, and IL-13. In general, type 1 cytokines favor the development of a strong cellular immune response whereas type 2 cytokines favor a strong humoral immune response. Some of these type 1 and type 2 cytokines are cross-regulatory. For example, gamma interferon and IL-12 decrease the levels of type 2 cytokines whereas IL-4 and IL-10 decrease the levels of type 1 cytokines. We use this cytokine perspective to examine human diseases including infections due to viruses, bacteria, parasites, and fungi, as well as selected neoplastic, atopic, rheumatologic, autoimmune, and idiopathic-inflammatory conditions. Clinically, type 1 cytokine-predominant responses should be suspected in any delayed-type hypersensitivity-like granulomatous reactions and in infections with intracellular pathogens, whereas conditions involving hypergammaglobulinemia, increased immunoglobulin E levels, and/or eosinophilia are suggestive of type 2 cytokine-predominant conditions. If this immunologic concept is relevant to human diseases, the potential exists for novel cytokine-based therapies and novel cytokine-directed preventive vaccines for such diseases.

Defective antigen-presenting cell function in patients with systemic lupus erythematosus

OBJECTIVE

Patients with systemic lupus erythematosus (SLE) who exhibit defective in vitro responses to recall antigens and normal responses to alloantigens have been shown to have an abnormality in antigen-presenting cell (APC) function. This study was undertaken to further characterize this defect in APC function in lupus patients.

METHODS

Mononuclear cells (MNC) from the peripheral blood of patients with SLE and from normal individuals were cultured in the presence of either recall antigen tetanus toxoid (TT), anti-CD3 (OKT3) monoclonal antibody, or alloantigens, and proliferative or interleukin-2 responses were assessed. Cell surface expression of B7-1 was assessed by flow cytometry.

RESULTS

MNC from all normal individuals and from 7 patients with SLE responded to both TT and alloantigen and were designated +/+. Twelve SLE patients did not respond to TT but did respond to alloantigen stimulation and were designated -/+. In both normal subjects and SLE patients, the ability to respond to OKT3 correlated strongly with the ability to respond to recall antigen. A defect in APC costimulatory function was suggested by data demonstrating that interferon-gamma-induced expression of B7-1 was significantly reduced in SLE patients compared with controls. Neither controls nor SLE patients expressed detectable amounts of surface B7-1 molecule on resting APC. Defective recall and anti-CD3-stimulated responses could be enhanced in SLE patients in the presence of B7/BBl-transfected P815 murine mastocytoma cells underscoring an SLE-associated defect in costimulatory activity. However, nontransfected P815 cells were also able to enhance responses to OKT3 in -/+ patients; blocking experiments showed that this was mediated through an IgG Fc receptor-dependent mechanism.

CONCLUSION

These data indicate that SLE-associated defects in APC function in vitro can be accounted for by abnormalities in APC surface membrane molecules such as B7, IgG Fc receptors, and possibly others.

Dysregulation of T helper cell cytokines in autoimmune prone NZB x NZW F1 mice

Multifactorial involvement in the pathogenesis of autoimmune NZB/W F1 mice has been well documented. To further elucidate the role of cytokines in the disease development of murine lupus, single spleen cells isolated from NZB/W F1 and non-autoimmune C57BL/6 mice were stimulated with T cell mitogens or anti-CD3 antibody at pre-determined optimal concentration. Supernatants were collected and assayed for production of cytokines including IL-2, gamma-IFN, IL-3, IL-4, IL-5 and IL-10. In both young and old mice, cytokine profiles by mitogen-stimulated T cells showed higher TH2 (type 2 T helper) cell-related cytokine production in NZB/W F1 mice compared to those in non-autoimmune C57BL/6 mice. In contrast, cytokines produced by TH1 (type 1 T helper) cells, such as gamma-IFN and IL-2, were lower in NZB/W F1 mice by stimulation with either mitogen or anti-CD3 antibody. In addition, cytokine production at different time points also demonstrated decreased gamma-IFN and increased IL-4 levels by anti-CD3 stimulated splenic cells in autoimmune NZB/W F1 mice. Furthermore, the IL-10 levels produced by lipopolysaccharide (LPS)-stimulated splenic and peritoneal exudate cells were higher in young NZB/W F1 mice compared to those in C57BL/6 mice. Our data suggest that dysregulation between TH1 and TH2 cells may play an important role in the pathogenesis of autoimmunity in NZB/W F1 mice.

Impaired polyclonal T cell cytolytic activity. A possible risk factor for systemic lupus erythematosus

OBJECTIVE

To determine whether impaired generation of polyclonal T cell cytolytic activity is over-represented in systemic lupus erythematosus (SLE) compared with other rheumatologic diseases and whether such impaired generation of cytolytic activity waxes and wanes with disease activity and/or changes in medications.

METHODS

Peripheral blood mononuclear cells from 84 SLE patients, 55 rheumatologic disease (RD) controls, and 44 normal subjects were stimulated with anti-CD3 monoclonal antibody, maintained in interleukin-2, and assayed for cytolytic activity against 51Cr-labeled Daudi target cells.

RESULTS

Generation of cytolytic activity was significantly lower in SLE patients than in either RD or normal controls. Abnormal cytolytic responses in SLE could not be attributed to the patient's sex, race, age, disease activity, or antirheumatic medications (including corticosteroids and cytotoxics), although both SLE and RD patients taking azathioprine (AZA) manifested lower responses than did corresponding patients not taking AZA. Abnormal cytolytic activity reflected, in large measure, impaired cytolytic activity of CD8+ T cells. No significant difference in the generation of cytolytic activity between RD and normal controls was detected.

CONCLUSION

Impaired generation of polyclonal T cell cytolytic activity may be a predisposing factor in the development of SLE.

CD30, Th2 cytokines and HIV infection: a complex and fascinating link

CD30 is a member of the tumor necrosis factor (TNF)/nerve growth factor (NGF) receptor superfamily, and was originally described as a marker of Hodgkin's and Reed-Sternberg cells in Hodgkin's lymphoma. CD30 is preferentially expressed on CD4+ and CD8+ T-cell clones that produce T helper 2 (Th2)-type cytokines, and is also released in a soluble form by these cells. Elevated serum levels of soluble (s)CD30 have been found in some conditions in which a pathogenic role for Th2 cells has been suggested, such as atopy, Omenn's syndrome, systemic lupus erythematosus, as well as following infection with measles virus or human immuno-deficiency virus (HIV). Here, Gianfranco Del Prete and colleagues suggest a complex and fascinating link between the expression and release of CD30, and the immunopathogenesis of HIV infection.