ABSTRACT
In the present review we have attempted to analyze recent findings concerning apoptosis of mature peripheral T cells. The great attention is made to the factors underlying resistance or sensitivity of mature T lymphocytes to activation-induced cell death. The role of preactivation and altered costimulation is discussed in this regard. Besides, the possible role of cytokines in the modulation of T cell apoptosis is emphasized. Particular attention is paid to the studies of apoptosis disorders in the pathogenesis of generalized bacterial infections. In this connection some own results are summarized as well. To characterize T cell death and its role in the pathogenesis of bacterial infections an anti-CD3-mAb or Con A-induced apoptosis in patients with severe and generalized forms of surgical infections have been investigated. We have found a significant increase of activation-induced lymphocyte apoptosis and a high level of apoptosis in freshly isolated lymphocytes in patients with surgical infections. Alternatively, peripheral blood mononuclear cells from surgical patients without infectious complications did not exhibit a marked enhancement of activation-induced cell death. Activation-induced T cell death in surgical infections appeared to be Fas-dependent, involved reactive oxygen intermediates and was partly prevented by pro-inflammatory cytokines, among which IL-2 exhibited the most pronounced anti-apoptotic activity. Likewise, APACHE II score, as a marker of the infection severity, directly correlated with a rate of activation-induced T cell apoptosis. Accelerated T cell apoptosis at the early stage of infection was revealed in survivors and non-survivors, that appears to designate a common pathway for the restriction of systemic inflammation. At the late stage of infection altered T cell apoptosis could account for different outcomes, since the patients with lethal outcome showed 2-fold increase in activation-induced cell death compared to the opposite group. Immunotherapy with rIL-2 declined anti-CD3-induced apoptosis and promoted a reduction in the mortality rate from 29% to 13%.
ABSTRACT
High-dose chemotherapy followed by hematopoietic stem cell (SC) transplantation has been recently proposed as a new strategy for the treatment of severe autoimmune diseases. The rationale for using stem cell transplantation to treat autoimmune disease is based on the principle of complete ablation of an aberrant immune system followed by reconstitution of a new immune system deriving from graft. Three different approaches are being currently used: 1) allogeneic SC transplantation, 2) autologous SC rescue following "immunoablation", and 3) intensive immunosuppression alone. By October 2000, a total of 310 patients who received SC transplantation for autoimmune diseases were registered in the European Group for Blood and Marrow Transplantation/European League Against Rheumatism. Five patients with primary severe autoimmune diseases (4 female and 1 male) were enrolled in our Institute from 1998 to 2000. Transplantations were made for systemic lupus erythematosus (SLE, n = 4) and idiopathic thrombocytopenic purpura (ITP, n = 1). Three SLE patients had lupus nephritis, lung vasculitis with pulmonary hypertension, secondary antiphospholipide syndrome, 1 SLE patient had central nervous system involvement with paraplegia, patient with ITP had a relapse after splenectomy and had unresponsive severe thrombocytopenia. Follow up is now 24 months for 1 SLE patient (she is in complete remission), 12 months for the 2nd SLE patient (partial response), ITP patient is well at present, platelets >100 x 10(9), dose of prednisolone is 10 mg/day. 2 SLE patients died on day +11 and +19 due to transplant-associated complications (sepsis). The study is still ongoing and longer follow-up is necessary to assess long-term efficacy of this treatment approach.
ABSTRACT
The investigations of 38 patients with pulmonary tuberculosis (PT) revealed combined T cell and monocyte functional disturbances. Indeed, the percentages of CD4(+) and CD8(+) T lymphocytes, proliferative response and IL-2 production, as well as the percentages of HLA DR(+) monocytes and IL-1beta production were significantly decreased in PT patients as compared with normal individuals. Herewith the absolute T lymphocyte number did not undergo the pronounced changes. The decrease of T cell proliferative response was not mediated through immunosuppressive action of monocytes or T lymphocytes since removing of "adherent" cells from patient's peripheral blood mononuclear cells (PBMC) or pretreatment of PBMC with indomethacin and cyclophosphan failed to recover mitogenic reactivity in vitro. The patient's sera also did not significantly influence on PBMC proliferation. The decrease of IL-2 production and the stimulation of T cell proliferative response via TcR-CD3 complex, i.e. through the classic pathway of activation, indicated the anergy of T lymphocyte in tuberculosis patients. Furthermore, T lymphocytes were characterized by enhanced apoptosis. It should be noted, that patient's sera (especially in the patients with an initially high apoptosis) promoted significant anti-apoptotic activity. It is likely that this mechanism may be an explanation, why absolute T lymphopenia is absent during tuberculosis infection. Our findings suggest, that T lymphocyte dysfunctions in patients with PT are caused by impairments of T cell activation process, which lead to predominance of "negative" response (induction anergy, apoptosis) and to a lesser degree connected with direct suppressive mechanisms mediated by monocytes, T lymphocytes or serum factors.
ABSTRACT
In the present study 37 patients with surgical infection were investigated and a new set of diagnostic tests for detection of major syndromes of systemic inflammation - systemic inflammatory response syndrome (SIRS), compensatory anti-inflammatory response syndrome (CARS) and mixed antagonist response syndrome (MARS) - was developed. In summary, we have demonstrated that patients with surgical infection were characterized by an immunodeficiency with significant reduction of mitogen-induced proliferation and IL-2/IL-4 production in vitro combined with decrease of HLA DR(+) monocytes. Furthermore, it was revealed that the patient's serum exhibited substantially enhanced suppressive and inflammatory activities as well as the level of C-reactive protein. We have defined the negative correlation between the serum inflammatory and suppressive activities (SIA and SSA) that was most prominent at the early stage of disease. Since the changes of serum bioactivity in the course of surgical infection were prominent and coherent, we supposed that tested activities might reflect the distinctive features of systemic inflammation. In according to this assumption, the patients were divided into 3 subgroups with predominance of SIRS, CARS and MARS by using the SIA and SSA expression. It has been shown that SIRS was more frequently detected at the early stage, whereas CARS - at the late stage of disease. Patients with SIRS, CARS or MARS significantly differed by the content of CD8(+) T and CD72(+) B lymphocytes, the concentration of IgG and IgA, the production of IL-2 and IL-4. Finally, the data obtained from patients, those were studied repeatedly, showed the possibility of transformation of the major systemic inflammatory syndromes during the disease course. Our findings suggest that measurement of serum inflammatory and suppressive activities may help to differentiate patients with SIRS, CARS or MARS and to select the appropriate strategy of immunotherapy.