A functional defect in the early phase of the immune response observed in patients with hemophilia A

Important decrease in invariant natural killer T, CD4+ regulatory T cells, CD8+ regulatory T cells, gamma-delta T cells, and CD4+ T lymphocytes in HIV-negative patients with hemophilia

Hereditary hemophilias are X-linked inherited bleeding disorders defined as deficiencies of the coagulation factors VIII or IX. They are characterized by easy to provoke or spontaneous bleeding. HIV infection in hemophilic patients is a risk factor for the reduction of CD4+ T cells. There is no information regarding the cellular immune function in HIV-negative patients with hemophilia. To evaluate the number of lymphocyte subsets in adult patients with hemophilia A or B as compared with healthy donors. 39 Adult hemophilics and 27 healthy donors were included. Lymphocyte subsets [CD4 and CD8 T cells, natural killer cells, natural killer T (NKT) cells, invariant NKT (iNKT) cells, gamma-delta T (γδT) cells, type 1 and 2 dendritic cells, CD14 monocytes, CD4 and CD8 regulatory T cells (Tregs), and B cells], were analyzed by flow cytometry. A significant decrease of CD4+ T lymphocytes, γδT cells, iNKT cells, CD4+ and CD8+ Tregs was observed in patients with hemophilia. Those patients having factor VIII inhibitor had the lowest CD4+ Treg and CD8+ Treg counts. CD14 monocytes were increased, as well as iNKT and type 2 dendritic cells in obese-overweight hemophilics. CD4+ lymphocytes, iNKT, γδT cells, and Tregs (CD4+ and CD8+), are significantly decreased in patients with hemophilia. Depletion of Tregs is more important in patients with factor VIII inhibitor. Physicians caring for hemophilia patients should realize that, even when they are not suffering infections frequently, may have early evidence of cellular immunodeficiency.

Laboratory and clinical markers of HIV infection in a national haemophilia cohort treated with recombinant factor VIII concentrate. The Association of Hemophilia Clinic Directors of Canada

Over an interval of approximately six months beginning in October 1993, most haemophilia A patients in Canada were switched from a plasma-derived intermediate-purity factor VIII concentrate (i.p. VIII) to a recombinant factor VIII (rVIII). In order to determine the consequence of this change in therapy on progression of HIV infection, we gathered surveillance data on clinical status and CD4 and CD8 cell counts in those patients who were HIV seropositive at the time of switching concentrates. Data were recorded at the time of switchover, annually for 2 years thereafter, and retrospectively at a point 1 year prior to the switch. CD4 cells fell significantly over the study period. Multiple direct comparisons revealed that this decline was restricted to the time intervals which included the final year in which patients received intermediate-purity factor VIII concentrate (i.p. VIII). In the 2 year interval in which rVIII was used exclusively, there was a nonsignificant fall in CD4 cells. Changes in CD4 cells did not correlate with the intensity of exposure to either i.p.VIII or rVIII. CD8 cells did not fall significantly over the study period. There was no obvious reduction in the incidence of death or clinical progression over the 2 years in which rVIII was used. However, we are hopeful that the stabilizing trend in CD4 cell counts which followed the introduction of rVIII will be predictive of corresponding clinical stabilization over the coming years.

Clotting factor concentrates and immune function in haemophilic patients

Patients with haemophilia often exhibit a variety of disturbances in immune function. Although infections with HIV, hepatitis and other viruses no doubt contribute to these abnormalities, chronic exposure to extraneous proteins in clotting factor concentrates (CFCs) may also play a role. Numerous in vitro and ex vivo studies show that protein contaminants--such as immunoglobulins, fibrinogen and fibronectin--can depress various immune function indicators. Generally, such studies show that intermediate-purity CFCs are more inhibitory than very high-purity (e.g. monoclonal-purified) CFCs. In many, but not all, studies, the degree of immunosuppression correlates with the amount of intermediate-purity CFC administered over time. Among various indicators of immune function, CD4+ lymphocyte number is a marker for the progression of HIV infection, and maintenance of CD4+ number is associated with delayed progression. A number of studies suggest that, compared with intermediate-purity CFCs, use of very high-purity CFCs is associated with longer preservation of this class of lymphocytes. However, it remains to be seen whether this translates to improved long-term clinical outcomes. Further research is needed on the impact of CFCs on the immune system. For the time being, however, evidence to date favours the use of very high-purity products because they appear to preserve immune function and reduce the risk of infection with hepatitis and other viruses.

Expression of dipeptidylaminopeptidase IV/CD26 in peripheral blood lymphocytes of hemophilic subjects

CD26 antigen, a 110 kDa membrane glycoprotein with exopeptidase activity (DAP IV), is an activation marker of T lymphocytes preferentially expressed on CD4+ memory cells and involved in T cell proliferation and IL-2 production after antigenic stimulation. We employed cytochemical and immunocytochemical techniques to study DAP IV/CD26 expression in circulating lymphocytes from 40 hemophilic patients, chronically treated with coagulation factors, in order to verify the possible involvement of this molecule in the immunological alterations of hemophilia. In all the hemophiliacs DAP IV activity was significantly lower than in the controls, independently of the quantity of blood transfused and previous exposure to viruses. This reduction may be responsible for the impaired proliferative response of lymphocytes to antigens and mitogens, notoriously observed in hemophilia. Whereas in the group of HIV- patients CD26 expression was similar to that of normal controls, in the 8 HIV+ hemophilic patients both percentages of positive lymphocytes and intensity of staining were significantly lower. In only 4 of the 8 cases was this deficit associated with CD4+ cell depletion. The significant selective loss of CD26 expression observed in HIV+ patients is probably an early event after HIV infection and seems to occur even before CD4 cell depletion. In conclusion, evaluation of DAP IV/CD26 might be a useful option for monitoring the immunological alterations of all hemophilic patients, HIV positive or not, chronically treated with coagulation factors.

Inhibition of IL-10 protein synthesis induces major histocompatibility complex class II gene expression in class II-deficient patients

Major histocompatibility complex (MHC) class II deficiency is an inherited autosomal recessive combined immunodeficiency, characterized by a lack of constitutive expression of the human leukocyte antigen (HLA) class II genes. The patients investigated in this study are histoidentical twin brothers with a new phenotype in MHC class II deficiency. Examination of HLA-D locus genes in their fractionated peripheral mononuclear cells (MNCs) revealed an unusual and uncoordinated mRNA pattern. Here we analyzed the distribution of pro- and anti-inflammatory cytokines expressed in these patients' adherent and nonadherent MNCs. We show that gene expression of IL-1 alpha, IL-1 beta, IL-6, granulocyte-colony-stimulating factor, and IL-10 was induced in both cell fractions, whereas increased mRNA levels of interferon-gamma and the inducible nitric oxide synthase were exclusively detected in the patients' nonadherent MNCs. As IL-10 is known to be able to downregulate transcription of MHC class II and expression of IL-10 in the patients' MNCs was increased, we investigated the regulatory function of this cytokine. Interestingly, inhibition of IL-10 protein synthesis with IL-10-specific antisense oligonucleotide DNA (IL-10-AS-ODN) induced HLA-D locus genes in these MHC class II-deficient patients. Exposure of the nonadherent cell fraction to IL-10-AS-ODN resulted in a profound induction of a previously absent DR beta 1 and DP alpha gene expression. HLA-DQ beta mRNA levels, however, were increased in both the adherent and the nonadherent MNC population. Albeit expression of HLA-D locus genes was inducible via inhibition of IL-10 translation, surface expression of HLA class II antigens on the patients' MNCs was essentially negative. The data presented support the concept of a coordinated network of pro- and anti-inflammatory cytokine regulation and this network obviously has a significant role in the cell-type-specific regulation of MHC class II expression.

Association of changes in monocyte antigen presentation and cytokine production in haemophilic boys with treatment and blood-borne virus infection

Aspects of monocyte function (antigen presentation and cytokine production (e.g. IL-1, IL-6) have been studied in a normal control population and three groups of haemophilic boys: group 1 HIV and HCV seronegative and treated only with a single heat-treated factor VIII (FVIII) concentrate; group 2 HIV seronegative but HCV seropositive; group 3 all HIV and HCV seropositive. Groups 2 and 3 have been previously treated with unheated and heated FVIII concentrate. Group 1 boys (HIV/HCV uninfected) showed no significant reduction in monocyte antigen presentation function nor IL-1 or IL-6 production when compared with a control population. Group 2 boys (HCV infected) showed a reduced monocyte antigen presentation activity (P < 0.05), but no significant reduction in IL-1 or IL-6 production. Group 3 boys (HIV and HCV infected) showed a significantly reduced monocyte antigen presentation activity (P < 0.001) and an impairment of IL-1 and IL-6 production (P < 0.05). A significant reduction of IL-1 and IL-6 production was only seen in the HIV and HCV infected haemophilic boys, implicating HIV as an aetiological agent. In contrast, reduced monocyte antigen presentation activity was seen in haemophilic boys with both HIV and HCV infection or HCV alone. The HIV and HCV seronegative boys had normal antigen presentation. The absence of immune modulation in haemophilic boys that have not acquired HIV and HCV infection suggests that chronic blood-borne virus infections as contributory to immune modulation seen in haemophiliacs with virus infections.

Molecular characterization of major histocompatibility complex class II gene expression and demonstration of antigen-specific T cell response indicate a new phenotype in class II-deficient patients

Major histocompatibility complex (MHC) class II deficiency is an inherited autosomal recessive combined immunodeficiency. The disease is known as bare lymphocyte syndrome (BLS). BLS is characterized by a lack of constitutive MHC class II expression on macrophages and B cells as well as a lack of induced MHC class II expression on cells other than professional antigen-presenting cells (APCs) due to the absence of mRNA and protein of the human leukocyte antigen (HLA) class II molecules, designated HLA-DR, -DQ, and -DP. The defect in gene expression is located at the transcriptional level and affects all class II genes simultaneously. Here we have analyzed transcription and protein expression of class II antigens in Epstein-Barr virus (EBV)-transformed B lymphoblastoid cell lines and mononuclear cells (MNCs) of twin brothers. Whereas flow cytometric analysis failed to detect class II antigens on the cell surface of the patients' EBV-B cells and MNCs, examination of the genes coding for HLA-DR, -DQ, -DP, and the invariant chain (Ii) by reverse transcriptase-polymerase chain reaction amplification resulted in an unusual mRNA pattern in the B cell lines of the patients (HLA-DR alpha +, -DR beta, -DQ alpha +, -DQ beta -, -DP alpha -; -DP beta +, Ii+). In accordance with these findings no HLA-DR beta-specific protein was detected by immunoblotting, whereas low levels of HLA-DR alpha and normal levels of Ii were present. In contrast to EBV-B cells, the MNCs of both patients displayed a residual HLA-DR beta, -DQ beta, and -DP alpha mRNA signal. Furthermore, HLA-DR beta-specific protein was found in addition to HLA-DR alpha by immunoblotting of cell lysates, even though it was clearly decreased as compared with controls. Our results indicate that the defect in class II antigen expression is not necessarily present to the same extent in B cells and cells of other lineages. mRNA levels of HLA-DR beta were found to be enriched in adherent cells within the MNC fraction. Further investigations indicated that the MHC class II expressed is functional in antigen presentation, as the two boys' CD4+ T cells became activated and expressed interleukin-2R after stimulation of peripheral blood mononuclear cell cultures with recall antigen (tetanus toxoid). Furthermore, T cells tested in one of the two patients responded to both MHC class I and II allostimulation, and this response was inhibited by monoclonal antibodies of the respective specificity.(ABSTRACT TRUNCATED AT 400 WORDS)

Immunological effects of intermediate purity clotting factor concentrates: failure to affect lymphocyte activation in vivo

Concern has been expressed that intermediate purity clotting factor concentrates may cause immunological abnormalities in haemophilic patients, distinct from those related to HIV infection. Early reports of lymphocyte dysfunction in anti-HIV seronegative haemophiliacs pointed to activation of their lymphocytes; a potential cause of CD4+ ve lymphocyte decline in anti-HIV seropositive patients. Recent reports have suggested that the use of high purity FVIII concentrates might retard the rate of decline in CD4+ ve lymphocytes in haemophiliacs infected with the HIV virus. Expression of markers of acute and chronic activation of T and B lymphocytes was measured in heavily treated anti-HIV seronegative haemophiliacs using two-colour flow cytometry. No T or B lymphocyte stimulation was observed. Cellular markers of activation were absent and CD4+ ve lymphocyte counts and serum IgG levels were normal. Anti-HIV seropositive haemophiliacs showed T and B cell activation consistent with HIV infection. The extent of lymphocyte activation in individual patients was unrelated to the type, amount or frequency of FVIII received. These findings do not support the hypothesis that lymphocytes of haemophiliacs are affected directly by the regular administration of intermediate purity concentrates so as to accelerate the progression of HIV disease.

Cellular and humoral immune responses in haemophiliacs after vaccination against tick-borne encephalitis

The primary immune response to a viral antigen (tick-borne encephalitis, TBE) has been determined in haemophiliacs. Twelve HIV-negative and four clinically asymptomatic, HIV-positive haemophiliacs as well as 16 age-matched healthy controls were included in the study. Antibody responses after TBE vaccination were comparable in HIV-negative haemophiliacs and controls; however, antibody titres in HIV-infected haemophiliacs were significantly lower after completion of the three-dose vaccination schedule (geometric mean reciprocal antibody titres (SEM): controls, 193 (1.37), HIV-positive haemophiliacs, 13 (2.18), P < 0.005). TBE vaccination failed to induce a T cell proliferative response in the HIV-positive haemophiliacs. While in HIV-negative patients the antigen-specific lymphoproliferative responses after primary and one booster vaccination were comparable to those of the controls, cellular responses were decreased in HIV-negative haemophiliacs following a second booster immunization 19 months after primary immunization (3H-thymidine incorporation, delta dpm, mean +/- SEM: controls, 34662 +/- 7129, HIV-negative haemophiliacs, 14339 +/- 7420, P < 0.005). As the protective mechanisms for TBE infection are not yet completely understood, further work will be necessary to determine whether the decreased capacity to mount a sufficient long-term cellular memory response in HIV-negative haemophiliacs might be important for the protective effect of TBE vaccination in this population.

Immunological abnormalities in haemophiliacs

10 years ago, it became apparent that haemophiliacs were developing diseases which were indicative of underlying immunodeficiency. The results of investigation confirmed that many had abnormal immune systems, particularly with regard to cell-mediated immunity. These abnormalities were thought to be a consequence of the use of clotting factor concentrates, and indeed the discovery of HIV and its mode of transmission, confirmed these suspicions. However, it subsequently became clear that HIV infection did not explain all the abnormalities observed. Many in vivo studies have shown that the immune systems of HIV-negative haemophiliacs are not entirely normal, and in vitro studies have shown that clotting factor concentrates per se have a modulating effect on immune function. We have reviewed particularly the abnormalities seen in HIV-negative haemophiliacs and their possible causes, as well as the specific features of HIV infection in haemophiliacs.

In vitro and in vivo inhibition of monocyte phagocytic function by factor VIII concentrates: correlation with concentrate purity

Seven factor VIII concentrates of varying purity (specific activity 0.67-10 units factor VIII procoagulant activity (VIII: C)/mg protein) have been examined over a range of concentrations (0.5-0.005 u/ml factor VIII) to establish their effect on in vitro monocyte phagocytic function. All these products inhibited monocyte phagocytic function, but the monoclonally purified product tested was significantly less inhibitory than the others (P less than 0.05). The degree of inhibition observed was independent of the virus inactivation method used to increase product safety. However, comparison of these products of differing purity from the same manufacturer showed that the inhibitory effect decreased as product purity increased. In vivo studies of monocyte function following infusion of two of these factor VIII concentrates demonstrated inhibition of circulating monocytes. The possible role of product purity in modulating immune responses in haemophiliacs is discussed.

Inhibition of lymphocyte IL2-receptor expression by factor VIII concentrate: a possible cause of immunosuppression in haemophiliacs

Factor VIII concentrate inhibits T-cell function in vitro and in vivo. The mechanisms underlying the phenomenon were investigated. Factor VIII concentrate has a direct effect on lymphocytes, uninfluenced by haemophilic monocyte dysfunction, since it inhibited lymphocyte transformation with phorbol myristate acetate, a reaction unaffected by monocyte depletion. Inhibition of lymphocyte transformation by factor VIII concentrate is not corrected by the addition of exogenous IL2, suggesting that it does not inhibit lymphocyte function by suppression of IL2 secretion alone. Factor VIII concentrate causes profound inhibition of IL2-receptor expression (CD25); with an 89% reduction in CD25-positive CD4 cells and a 50% reduction in CD25-antigen molecules per cell. CD8 lymphocytes are similarly affected. Smaller reductions in CD71 and HLA-DR expression are also observed. Down modulation of CD25-antigen may explain the reduced IL2 secretion observed by others, and may be an important cause of immunodeficiency in HIV-seronegative haemophiliacs.

Identification of individuals at increased risk for AIDS among clinically asymptomatic homosexuals and abusers of intravenous drugs

Immunological parameters previously shown to constitute an increased risk for progression towards AIDS have been observed in clinically asymptomatic individuals considered to be at risk for this syndrome. These parameters include severely decreased numbers of T helper cells (count below 400/mm3 blood for CD4+ cells were detected in 7 our of 33 HIV antibody-positive, asymptomatic homosexuals and in 3 out of 29 HIV antibody-positive, asymptomatic drug abusers) and elevated serum IgA and IgM levels (found in 7 to 30 percent of these subjects). Furthermore, up to 60% of risk group members showed a decreased lymphoproliferative response to tetanus toxoid as compared to only 11% of so-called low responders in the simultaneously tested healthy controls. Finally, the capacity to mount an immune response to viral glycoproteins was found to be impaired in individuals at risk for AIDS, as indicated by a low serum level of antibodies to tick-borne meningoencephalitis virus antigen in recently vaccinated subjects.

Effect of polymeric IgG on human accessory cell function

Circulating immune complexes are considered to have a profound effect on host defense mechanisms against invading pathogens and to modulate cellular interactions required for an appropriate course of the immune response. In this study we have investigated the influence of polymeric IgG (used as a model system for immune complexes) on accessory functions of human monocytes. We show that a short (1 hr) incubation of human monocytes in the presence of polymeric IgG (16 hr prior to antigen pulsing) led to a significant decrease of these cells' antigen-presenting capacity while accessory functions in alloantigen- or mitogen-driven proliferation systems remained unimpaired. The polymeric IgG-induced impairment of antigen presentation, which was assessed by diminished proliferation of antigen-reactive T cells following stimulation by antigen-pulsed polymeric IgG-treated or Dulbecco's phosphate-buffered saline (PBS-D)-treated control monocytes, could not be attributed to the generation of suppressor mechanisms (no release of soluble suppressor factors, no induction of suppressive monocytes). The release of interleukin-1 by polymeric IgG-treated monocytes and PBS-D-treated monocytes was comparable and polymeric IgG did not down modulate major histocompatibility complex (MHC) class II molecules already expressed in the monocyte plasma membrane. Profound changes in the monocyte plasma membrane occurring subsequent to polymeric IgG treatment possibly accompanied by altered kinetics of MHC class II reexpression are likely to contribute to the observed decrease of antigen presentation.