Recent studies on animal and human autoimmune hemolytic anemia (AIHA) suggest that immunological tolerance loss toward red blood cells (RBC) self-antigens may be originate by different, non-mutually ...exclusive, mechanisms. According to now available data the identified mechanisms may be: ignorance against RBC self-antigens; molecular mimicry; polyclonal T and/or B cells activation; errors in central or peripheral tolerance; immunoregulatory disorders including cytokine network alteration.
In some patients with AIHA, stimulation of PMBC by synthetic Rh peptides indicate that ignorant T and/or B cell clones may recognize cryptic RBC self-antigens. AIHA associated with bacterial or viral infections seems to be produced by polyclonal T and/or B cells activation against foreign antigens which mimic protein or carbohydrate epitopes on RBC. Polyclonal activation of host B cell clones by donor alloreactive T cells causes the AIHA in chronic GVHD. As the tolerance loss is concerned, experiments on mouse lines expressing a transgene with autoantibody activity against murine RBC have shown that non-deleted peripheral B cell clones may produce RBC autoantibodies. In humans a genetic defect of Fas/FasL autoreactive lymphocytes apoptosis may be associated to AIHA. Immunoregulatory disorders due to depletion of CD4+ CD25+ T cells or Th1/Th2 cytokines imbalance may induce autoimmune diseases. In mice AIHA may be induced or improved by cytokines or anticytokine antibodies administration. In NZB/W mice and human AIHA there is an increased production of Th2 cytokines as IL4 and IL10 but INF- reduced production. In addition in human AIHA has been shown a downregulation of IL12 and therefore, an IL10/IL12 immunoregulatory circuit imbalance which might facilitate the RBC autoantibodies production.
Recent studies about autoimmune diseases in animal models and in humans focused their attention on lymphocyte activation and in vitro cytokine production. The respective contribution of the Th1 and ...Th2 cytokines to the pathogenesis of autoimmune diseases is still a matter of debate. In this study the role of IL-2, IL-4, IFN- n, IL-10 and IL-12 cytokines were investigated by examining their spontaneous and mitogen-induced (OKT3 and PHA or LPS) synthesis and T-cells proliferative response by peripheral blood mononuclear cells to determine their role in the pathogenesis of AIHA. Thirteen patients affected by AIHA, idiopathic or associated with other diseases, and 13 healthy subjects, randomly selected from a group of blood donors, were investigated. This study indicated that AIHA is characterised by increased basal synthesis of IL-4 and decreased levels of IFN- n compared with healthy controls ( p <0,01). These results suggest that there is a basal decrease of Th1 cytokine and an increase of the Th2 ones. Enhanced IL-2 levels in AIHA patients are likely due to the necessity of a T-cell proliferation stimulus rather than produced as Th1 prevalent stimulation. Furthermore, it has been observed a significant increase in IL-12 production in LPS stimulated cultures from healthy controls, but not in AIHA patients, that shows IL-10 increased levels, which could cause a secondary decrease in IFN- n production and a stimulation of Th2 differentiation. These observations indicate that decreased production of Th1-type cytokines and prevalent Th2 ones leading to autoantibodies production in AIHA may be secondary to the imbalance between IL-10 and IL-12. These results strongly suggest that manipulation of the cytokine network, i.e. IL-10/IL-12 balance, maintained by cells of the innate immune system, can have a strong effect on the incidence of AIHA and their modulation might be useful for a therapeutic control of the disorder.
Recent studies on animal and human autoimmune hemolytic anaemia (AIHA) suggest that the loss of immunological tolerance vs. erythrocyte (Er) self antigens (Ag) may be primed by different mechanisms: ...ignorance of Er self Ag, molecular mimicry between self and non-self Ag, policlonal T and/or B cells activation, errors in central or peripheral tolerance, immunoregulatory disturbances including the alteration of cytokines network. In vitro stimulation by synthetic Rh peptides indicates that ignorant T and/or B cells from patients with AIHA may recognize criptic Er self Ag. The AIHA associated with bacterial or viral infections seems to be produced by policlonal T and/or B cell activation against foreign Ag that mimics protein or carbohydrate epitopes on Er. Policlonal activation of host B cell clones by donor T cells causes the AIHA in chronic graft-versus-host disease. Mouse lines expressing a transgene with autoantibody (autoAb) activity against murine Er have shown that non-deleted peripheral B cell clones may produce Er autoAb. In human a genetic defect of Fas/FasL autoreactive lymphocyte apoptosis may be associated with AIHA. Th1/Th2 cytokines or IL10/IL12 imbalance may induce AIHA: in NZB mice and in human AIHA there is an increased production of Th2 cytokines such as IL4 and IL10 but INF-γ and IL12 reduced production. Particularly, IL10 seems to act as critical mediator for the Er autoAb production.
: In animal and human autoimmune hemolytic anemia (AIHA) immunologic tolerance loss against RBC self‐antigens could be originated by several mechanisms: ignored self‐antigens' epitopes, polyclonal ...lymphocyte activation, molecular mimicry between self‐ and foreign antigens, central or peripheral tolerance errors, or immunoregulatory disturbances including the alteration of a cytokine network. To identify the immunologic factors contributing to autoimmune onset and maintenance, several murine strains (such as NZB and NZB/NZW) that spontaneously develop a complex autoimmune syndrome, including AIHA, have been extensively studied. In human AIHA, the respective roles of IL‐2, IL‐4, IFN‐γ, IL‐10, and IL‐12 were investigated by examining the spontaneous and mitogen‐induced (OKT3 or LPS) production of these cytokines. ELISA methods were used in PBMCs to evaluate whether the manipulation of IL‐10/IL‐12 balance can have an effect on the incidence of autoimmune diseases and whether this might be useful for the control of AIHA. Results affirmed that AIHA is a disease that exhibits an increased basal synthesis of IL‐4 and decreased levels of IFN‐γ by AIHA PBMCs compared with controls and that there is a basal increase of Th2 cytokines. Th1‐type cytokine decrease in the basal state occurred in parallel with an increase of constitutive IL‐10 production and an IL‐12 decrease. In conclusion, decreased production of Th1‐type cytokines and the production of autoantibodies in AIHA may be secondary to the imbalance between IL‐10 and IL‐12, and the neutralization of IL‐10 may be efficacious in diminishing the clinical pathology associated with Th2 subset prevalence. In the same way, the treatment with IL‐12 could offer a second and independent level of blockade against the consequences of the overstimulation of B cells associated with AIHA.
AIHA is characterised by the destruction of antibody-coated red blood cells, but the mechanism that initiates the production of autoantibodies remains unclear. We have studied the proliferative ...response and the spontaneous and mitogen-induced (PHA and OKT3) synthesis of IFN-g, IL-2 and IL-4 by peripheral blood mononuclear cells from patients with AIHA before any treatment to investigate the activation of Th1 and Th2 subsets.
Thirteen AIHA patients, both idiopathic and associated with other diseases, were studied by ELISA methods and H3 thymidine incorporation to determine in vitro cytokine production and T cell proliferative response, respectively.
Under basal conditions the proliferative response induced in peripheral blood mononuclear cells was enhanced in AIHA patients suggesting a basal state of hyperactivation. This increase in proliferative response can be related to the basal enhanced levels of IL-2 (p<0.04), a key cytokine, that regulates the growth, differentiation and function of lymphocytes. High IL-2 levels in AIHA patients supernatants, with or without OKT3 stimulation, justify the high basal activation of T lymphocytes. Under basal conditions levels of IFN-g are decreased and IL-4 levels are increased.
AIHA is characterised by the destruction of antibody-coated red blood cells, but the mechanism that initiates the production of autoantibodies remains unclear. But looking to this data it is possible to suppose that there is a prevalent contribution of Th2 lymphocytes to the pathogenesis of AIHA.
We studied 16 patients affected by autoimmune hemolytic anaemia (AIHA), both idiopathic and associated with other diseases (B and T lymphoma, B hepatitis, gastric carcinoma, systemic lupus ...erythematosus) or alpha-methyldopa therapy, in order to value T- and B-cell activation. We determined the count of T- and B-cell subsets in peripheral blood, the proliferative response of peripheral blood lymphocytes (PBL) to phytohemagglutinin (PHA) and to pokeweed mitogen (PWM), the percentage of CD25+ cells in culture and interleukin (IL)-1alpha, IL-2, IL-4, tumor necrosis factor (TNF)alpha and soluble IL-2 receptor (sIL-2R) levels in sera and in culture. Except for an increase in CD4+ and CD8+ T cell number in a case of AIHA associated with a T lymphoma and an increase in the percentage of CD5+ and PCA1+ B cells in two cases of AIHA associated with B lymphoma and with SLE, no further data showed a relationship with the disease possibly associated with AIHA, so both idiopathic and secondary AIHA cases were analyzed together. CD4+ T cells were reduced in number in 9 cases, while CD8+ T cells were reduced in 6 cases. The percentage of CD5+ B cells was increased in 5 cases. The percentage of PCA1+ cells was increased in all cases (mean +/- sd: 18 +/- 22 vs 0,2 +/- 1 in controls). The average PBL proliferative response to PHA was reduced (S.I. 71 +/- 55 vs 138 +/- 45 in controls) as well as that to PWM (S.I. 27 +/- 21 vs 75 +/- 24 in controls), despite IL-2 high levels, in all cases, in both sera (mean +/- sd: 648 +/- 351 pg/ml vs 16 +/- 4 pg/ml in controls) and culture supernatants (mean +/- sd: 1045 +/- 677 pg/ml vs 195 +/- 51 pg/ml in controls). In PHA stimulated cultures the percentage of CD25+ cells was reduced (mean +/- sd: 37 +/- 18 vs 63 +/- 14 in controls), sIL-2R levels were like controls in 7 cases. In sera sIL-2R levels were increased in all cases (mean +/- sd: 1256 +/- 465 U/ml vs 256 +/- 114 U/ml in controls), IL-1alpha was increased in all cases too, while IL-4 levels were increased only in 7 cases. Linear regression analysis generally showed a low relationship between S.I. and IL-2, IL-4 and sIL-2R levels in supernatants of PHA stimulated culture as well as between S.I. and the percentage of CD25+ cells. Taken together these data suggest a state of B- and T-cell hyperactivation in AIHA. The low PBL proliferative response in vitro, explained in previous studies as a temporary functional exhaustion, might be itself a sign of the complete lymphocyte activation occurring in vivo in AIHA.
Our previous studies on autoimmune haemolytic anaemia (AIHA) have shown a hyperactivation concerning cytokine production in T and B lymphocytes obtained from AIHA patients. In this study the ...production of interleukin (IL)-10, basal and stimulated by lipopolysaccharide (LPS), was determined in cultured monocytes obtained from patients affected by AIHA, either idiopathic or associated with other autoimmune diseases, e.g. idiopathic thrombocytopenic purpura (ITP), systemic lupus erythematosus (SLE), myastenia gravis (MG). In cultured AIHA monocytes the IL-10 basal production (mean ± SD) was increased in all but one patient, compared to the controls, 125.96±76.10 pg/mL and 19.18±15.80 pg/mL respectively. Specifically, LPS stimulation was able to induce a higher IL-10 production by monocytes in two AIHA cases, whereas in five patients there was no difference and in two cases the LPS stimulated IL-10 production was even decreased compared to the levels observed in the controls. Interestingly in the latter two cases AIHA was associated with other autoimmune diseases (ITP, SLE). These results indicate a constitutively higher basal IL-10 production in monocytes from AIHA patients. The increased level of IL-10 could play an important role in the modified pathways of the immune response in AIHA.
Aims: Several immunological mechanisms seems to be similar in cancer and autoimmune disease. Studying interleukins production and proliferative response in autoimmune haemolytic anaemia (AIHA), it is ...possible to observe that manipulation of IL-10/IL-12 balance can have profound effect on the incidence of autoimmune diseases and this might be useful for the control of AIHA.
Methods: Respective role of IL-2, IL-4, IFN-γ, IL-10 and IL-12 in non-cancer associated AIHA were investigated by examining the spontaneous and mitogen-induced (OKT3 or LPS) synthesis of these cytokines in PBMC cultures by ELISA methods.
Results: Our results affirmed that AIHA is a disease which exhibited an increased basal synthesis of IL-4 and decreased levels of IFN-γ by AIHA PBMC compared with controls and then there is a basal increase of Th2 cytokines. Th1-type cytokine decrease in basal state occurred in parallel with an increase of constitutive IL-10 production and a IL-12 decrease.
Conclusions: Decreased production of Th1-type cytokines and the production of autoantibodies in AIHA may be secondary to the imbalance between IL-10 and IL-12 and then the neutralisation of IL-10 may be efficacious in diminishing the clinical pathology associated with Th2 subset prevalence. In the same way, the treatment with IL-12 could offer a second and independent level of blockade against the consequences of the over B cell activation associated with AIHA and sometimes with cancer.
In autoimmune diseases striking abnormalities of T and B cell activation and of cytokine production are present. In 14 patients with autoimmune hemolytic anemia (AIHA), idiopathic or in the course ...of: lymphoma, B hepatitis, carcinoma, drug therapy (alpha-methyldopa), systemic lupus erythematosus (SLE), and not yet submitted to immunosuppressive therapy, the PBL proliferative response to PHA and the IL1 alpha, IL2, IL4 and IL2R serum levels have been valued. While the stimulation index of PBL was strongly reduced in 10 cases (64 +/- 56 vs 138 +/- 45 in the control group), IL1 alpha, IL2 and IL2R were greatly increased in all the patients, and IL4 in 5 (IL1 alpha :199 +/- 268 pg/ml in patients vs 0.30 +/- 0.2 in controls; IL2:716 +/- 311 pg/ml vs 16 +/- 4; IL4:29 +/- 13 pg/ml vs 13 +/- 7; IL2R:1233 +/- 471 U/ml vs 256 +/- 114). Cytokine serum levels were not related with the associated disease, with the CD4+ and CD8+ cells absolute number or with PBL blastogenic in vitro response. The high serum levels of cytokines and IL2R suggest that in AIHA there exist a CD4+ lymphocyte hyperactivation (the low proliferative response of PBL might imply a temporary functional exhaustion of T lymphocytes) as in the other autoimmune diseases.
Recent studies on animal and human autoimmune hemolytic anemia (AIHA) suggest that immunological tolerance loss toward red blood cells (RBC) self-antigens may be originate by different, non-mutually ...exclusive, mechanisms. According to now available data the identified mechanisms may be: ignorance against RBC self-antigens; molecular mimicry; polyclonal T and/or B cells activation; errors in central or peripheral tolerance; immunoregulatory disorders including cytokine network alteration. In some patients with AIHA, stimulation of PMBC by synthetic Rh peptides indicate that ignorant T and/or B cell clones may recognize cryptic RBC self-antigens. AIHA associated with bacterial or viral infections seems to be produced by polyclonal T and/or B cells activation against foreign antigens which mimic protein or carbohydrate epitopes on RBC. Polyclonal activation of host B cell clones by donor alloreactive T cells causes the AIHA in chronic GVHD. As the tolerance loss is concerned, experiments on mouse lines expressing a transgene with autoantibody activity against murine RBC have shown that non-deleted peripheral B cell clones may produce RBC autoantibodies. In humans a genetic defect of Fas/FasL autoreactive lymphocytes apoptosis may be associated to AIHA. Immunoregulatory disorders due to depletion of CD4+ CD25+ T cells or Th1/Th2 cytokines imbalance may induce autoimmune diseases. In mice AIHA may be induced or improved by cytokines or anticytokine antibodies administration. In NZB/W mice and human AIHA there is an increased production of Th2 cytokines as IL4 and IL10 but INF-% reduced production. In addition in human AIHA has been shown a downregulation of IL12 and therefore, an IL10/IL12 immunoregulatory circuit imbalance which might facilitate the RBC autoantibodies production.
