Defective Fc-receptor functions associated with the HLA-B8/DRw3 haplotype: studies in patients with dermatitis herpetiformis and normal subjects

Impact of HLA polymorphisms among cadaveric donors on kidney graft allocation

This study provides data on HLA-A, -B, and -DRB1 frequencies among 861 end-stage renal disease (ESRD) patients from Croatia and estimates the benefit of the kidney exchange program by comparing HLA distribution and assessing HLA mismatches (MMs) within a group of ESRD patients who received kidney grafts from 707 cadaveric donors (422 from Croatia and 285 from Eurotransplant). Patients positive for HLA-B*07, -B*08, or -B*44 genes more often received a kidney from ET donors, while HLA-DRB1*11 and -DRB1*16 positive patients more frequently received a kidney from CRO donors. ABDR MM 000 was more frequently present in the case of transplantation from ET donors, while MM 222 was significantly more frequent when the donor was from Croatia. Sensitized patients received kidney more frequently from ET donors (P < .0001). A large pool of organ donors with different HLA gene distributions allows for a higher probability of transplantation from HLA highly matched donor.

Chronic stress induced duration dependent alterations in immune system and their reversibility in rats

The objective was to find out whether severity of stress effects on immunity increases with duration of exposure and recovery depends on duration of exposure. Adult male rats (n = 30) were subjected to restraint (1 h) followed by forced swimming exercise (15 min) after a gap of 4 h daily for 2, 4 and 8 weeks and allowed to recover for 6 weeks after each exposure period. Exposure of rats to stress resulted in duration dependent significant decreases in leukocyte count, phagocytic indices of neutrophils, number of bone marrow stem cells and serum levels of IL-12 and increases in apoptotic index of peripheral blood mononuclear cells and serum levels of IL-10. The alterations in counts of neutrophils, total immunoglobulin content, phagocytic index, apoptotic index of peripheral blood mononuclear cells and serum levels of IL-10 returned to control levels in recovery group rats of 2 and 4 weeks exposure but not in that of 8 weeks exposure. However, alterations in number and apoptotic index of bone marrow stem cells returned to control levels in 2, 4 and 8 weeks stress recovery groups. The results for the first time reveal that increase in duration of exposure results in more severe damage in immune system and that shorter the exposure period, faster the recovery. In addition, in vitro study for the first time showed that corticosterone causes apoptosis of peripheral blood mononuclear cells and bone marrow stem cells in dose dependent manner. Hence death of leukocytes and their stem cells is the major cause of stress induced immune dysfunction.

Clinical Role of Human Leukocyte Antigen in Health and Disease

Most of the genes in the major histocompatibility complex (MHC) region express high polymorphism that is fundamental for their function. The most important function of human leukocyte antigen (HLA) molecule is in the induction, regulation of immune responses and the selection of the T cell repertoire. A clinician's attention is normally drawn to a system only when it malfunctions. The HLA system is no exception in this regard, but in contrast to other systems, it also arouses interest when it functions well - too well, in fact. Population studies carried out over the last several decades have identified a long list of human diseases that are significantly more common among individuals that carry particular HLA alleles including inflammatory, autoimmune and malignant disorders. HLA-disease association is the name of this phenomenon, and the mechanism underlying is still a subject of hot debate. Social behaviours are affected by HLA genes and preference for HLA disparate mates may provide 'good genes' for an individual's offspring. Also, certain HLA genes may be associated with shorter life and others with longer lifespan, but the effects depend both on the genetic background and on the environmental conditions. The following is a general overview of the important functional aspects of HLA in health and diseases.

Association between Human Leukocyte Antigens (HLA-A, -B, and -DR) and end-stage renal disease in Kuwaiti patients awaiting transplantation

The number of patients with end stage renal disease (ESRD) is increasing considerably worldwide. Human Leukocyte Antigens (HLAs) are relevant for the expression of many immunological diseases and contribute to the development of different nephropathies. Therefore, we aimed from the present work to investigate the possible association between the frequency of HLA-A, -B, and -DR antigens and ESRD in Kuwaiti patients awaiting renal transplant. HLA-A, -B, and -DR typing was performed by complement-dependent cytotoxicity (CDC) method for 334 patients with ESRD awaiting renal transplantation and 191 healthy controls. The frequency of HLA-B8 antigen was significantly higher in ESRD patients (OR = 2.62, p = 0.001, pc = 0.038), and the frequency of HLA-A28, HLA-DR11 antigens was significantly higher in healthy controls (OR 0.42, p = 0.0001; pc = 0.0021, and OR = 0.44, p = 0.0007, pc = 0.01 respectively). While the HLA-B8 antigen may be a susceptibility risk factor for development of ESRD, the HLA-A28, and HLA-DR11 antigens may be protective against development of ESRD in Kuwaiti population.

HLA-B8, DR3: a new risk factor for graft failure after renal transplantation in patients with underlying immunoglobulin A nephropathy

BACKGROUND

The HLA-B8, DR3 haplotype has been associated with high immune reactivity. In this study, we have tested whether this haplotype has differential effect on graft survival in patients with IgAN compared with control patients.

METHODS

From the Eurotransplant Registry we analyzed graft survival of 1207 recipients with IgAN and 7935 control patients with non-glomerular diseases. Death-censored graft loss according to the HLA-B8, DR3 haplotype was calculated with Kaplan-Meier analysis and Cox-regression model was used to correct for various risk factors.

RESULTS

The frequency of the HLA-B8, DR3 haplotype was significantly lower in IgAN patients compared with controls (10.3% vs. 15.4%, p < 0.001). Ten-year graft survival was identical in the control group with and without the HLA-B8, DR3 haplotype (71.1% and 70.2%, respectively), but significantly worse in IgAN patients carrying the HLA-B8, DR3 haplotype compared with patients without it (52.5% vs. 69.1%, respectively, p = 0.009). The risk of graft loss was increased by 66% (HR 1.6, 95% CI 1.14, 2.29) in IgAN with the HLA-B8, DR3 haplotype and independent of well-known risk factors.

CONCLUSIONS

We have identified a new risk factor for graft loss unique to patients with IgAN. This finding emphasizes the exclusive immune characteristics of IgAN patients after transplantation.

B-cell function and islet cell and other organ-specific autoantibodies in relatives to insulin-dependent diabetic patients

The pancreatic B-cell function (glucose tolerance, C-peptide release) and organ-specific autoantibodies, including islet cell cytoplasmic and cell surface (mouse), were studied in 45 first-degree relatives of patients with insulin-dependent diabetes mellitus diagnosed before the age of 30 years. Compared to 107 healthy persons without any family history of either insulin-dependent or non-insulin-dependent diabetes mellitus, the prevalence of autoantibodies was increased among the relatives. The prevalence of islet cell antibodies did not differ between relatives and controls and none of the individuals had complement-fixing islet cell antibodies. There was no difference in glucose tolerance or C-peptide release between relatives and controls, whether they had autoantibodies or not. At a three-year follow-up, none of the individuals had developed insulin-dependent diabetes.

Speculations on potential anti-receptor autoimmune diseases

Many autoimmune disorders have a strong tendency to cluster in a single patient or type of patient. Therefore, in those cases in which anti-receptor antibodies are known to be responsible for one of the diseases in the cluster, it is logical to proceed investigatively on the presumption that the aetiology of other members of the cluster may also have an anti-receptor autoantibody basis. This logic is examined by considering examples of clustering in human diseases involving both organ-specific and non-organ-specific autoimmunities. The strong relationship between clustering among autoimmune diseases and the HLA-B8/DRw3 haplotype may provide a marker for anti-receptor autoimmune diseases.

Functional regulation of human neutrophil Fc gamma receptors

Interaction between Fc receptors expressed on phagocytic cells and antibodies play a critical role in innate immune response. Interestingly, immune cells such as neutrophils, monocytes, and dendritic cells (DCs) express multiple Fc receptors for IgG (FcgammaR) with overlapping ligand specificity. These receptors compete for the same ligand on the target and are known to transduce positive and negative signals to the same cell, depending on presence of type of signaling motif in their cytoplasmic domain. Neutrophils, the first line of defense against bacterial infection and the major phagocytic cell in the blood, express two types of FcgammaRs depending on the species. In humans, the neutrophils co-express immunoreceptor tyrosine-based activation motif (ITAM) containing CD32A and glycosyl-phosphatidyl inositol (GPI)-anchored CD16B, which is in contrast to co-expression of ITAM containing CD16A and ITIM containing CD32B in mouse neutrophils. Recent studies in gene knockout mice have demonstrated that the negative signaling by CD32B plays a critical role in preventing immune complex (IC)-mediated autoimmune diseases by regulating the activation signal delivered by CD16A. However, it is not known how the function of ITAM signaling CD32A is regulated in human neutrophils. Recent observations from our laboratory suggest that in human neutrophils, the CD32A receptor is regulated at the ligand-binding stage. Using a CD16B-deficient donor, we found that the CD32A expressed on resting neutrophils is unable to bind ligand; however, once neutrophils are activated with fMLP, a bacterial chemotactic peptide, the CD32A is functionally active in binding ligand. We also observed that this regulation is neutrophil-specific phenomenon. These observations suggest that FcgammaR can be regulated by distinct mechanisms and factors such as membrane-anchoring, cell-specific signaling, and avidity modulation that may be coordinately involved in regulating the function of human FcgammaR. Because neutrophils may be activated during infectious and inflammatory diseases, the knowledge of functional regulation of FcgammaR will be useful in designing therapies for many autoimmune diseases.

Dermatitis herpetiformis: close to unravelling a disease

Dermatitis herpetiformis is characterised by granular IgA precipitates in the papillary dermis. In contrast to other autoimmune blistering diseases, where tissue-deposited and circulating autoantibodies recognise the same target within the skin, in dermatitis herpetiformis a serum IgA reacting with a component of the healthy papillary dermis has not been detected. Recently, the antigenic specificity of pathognomic skin-bound IgA has been clarified: the immune precipitates contain epidermal transglutaminase, an enzyme not previously detected in the papillary region of normal skin. Furthermore, serum IgA in dermatitis herpetiformis has been found to bind epidermal transglutaminase. These findings may relate to the fact, that dermatitis herpetiformis is associated with gluten sensitive enteropathy, coeliac disease, which is characterised by IgA type autoantibodies to a closely related enzyme, tissue transglutaminase. The two transglutaminases are highly homologous, and therefore, cross reactivity of the two antibodies might explain why patients with gluten sensitive enteropathy, with or without skin disease, generally have serum autoantibodies to both enzymes. There is growing evidence that dermatitis herpetiformis should be considered as the skin manifestation of gluten sensitivity developing in those patients with mild coeliac disease, who produce epidermal transglutaminase autoantibodies of high avidity and affinity. Both the skin and the small bowel diseases are gluten dependent and are strongly associated with HLA DQ with no genetic differences to explain the two phenotypes. The question should be asked whether the rash in dermatitis herpetiformis is a classic autoimmune blistering disease or whether it has an immune complex basis, which is the most likely alternative.

The HLA-DR phenotype of the responder is predictive of humoral response against HLA class I antigens

Recent studies suggest that the immunogenicity of an human leukocyte antigen (HLA) incompatibility should be considered in the context of the HLA phenotype of the recipient. The HLA-DR phenotype of the responder is thought to be predictive for the strength of the alloimmune response. In order to analyze the humoral response against HLA class I antigens in the context of the HLA-DR phenotype of the responder, we selected all HLA-DR homozygous Dutch patients that were present on the Eurotransplant waiting list between 1967 and 2000 (n=1,317 patients). By logistic regression it was determined whether antibody production against a specific HLA class I antigen is associated with a particular HLA-DR antigen in the patient. Furthermore, it was analyzed whether a patient, expressing a particular HLA-DR antigen, preferentially produces antibodies against particular HLA class I antigens. The results demonstrate that patients, homozygous for a certain HLA-DR antigen, cannot be considered high or low responders when analyzing the antibody response in terms of panel reactive antibody (PRA) value. However, a correlation can be found between the HLA-DR phenotype of the patient and the specific antibody response against HLA class I antigens. For example, antibodies against HLA-A10, -A11, -A19, and -B35 are produced more frequently by HLA-DR6 positive individuals, whereas antibodies against HLA-A3, -B5, -B7, -B8, and -B12 are produced more frequently by HLA-DR4 positive individuals. These data confirm that the HLA-DR phenotype of the responder plays a determinative role in the immunogenicity of mismatched HLA antigens. The results indicate that selection of HLA class I mismatches of the donor in the context of the HLA-DR phenotype of the responder might reduce the incidence of humoral graft rejection and minimize the sensitization grade of retransplant candidates.

IgA deficiency: clinical correlates and responses to pneumococcal vaccine

We surveyed historical and laboratory data for 127 IgA-deficient patients (ages 2-67), referred to an immunology clinic; the commonest medical history was recurrent respiratory infections (50%), followed by autoimmunity (28%) asthma and allergy (13%). Fifty-two subjects have been given a pneumococcal vaccination; vaccine responses to 12 serotypes were significantly related to serum IgG2 levels (P = 0.004). Six immunized IgA/IgG2-deficient subjects produced insignificant amounts of antibodies to these pneumococcal serotypes; 10 others with normal IgG2 levels also had subnormal vaccine responses. IgA-deficient patients who had at least one B8 allele (n = 19) had a significantly greater response to this vaccine than the HLA-B8-negative subjects (n = 24) (P = 0.024). There was no relationship between a history of recurring infections and pneumococcal vaccine responses; HLA status was not related to a history of autoimmunity.

Clearance of red cells by monoclonal IgG3 anti-D in vivo is affected by the VF polymorphism of Fcgamma RIIIa (CD16)

Human red cells (RBC) coated with IgG anti-D are cleared from the circulation to the spleen by macrophages which express IgG receptors (Fcgamma R). Polymorphisms of Fcgamma RIIa and Fcgamma RIIIa affect IgG binding in vitro, and may alter the efficiency of clearance of immune complexes in vivo. In a RBC clearance study, 22 Rh D-negative subjects were given 100-400 micro g human monoclonal or polyclonal IgG anti-D i.m. followed 48 h later by 51Cr-labelled D+ RBC. The half lives of the infused D+ RBC were determined, together with the coating levels of anti-D on the D+ RBC. Fcgamma RIIA and FcgammaRIIIA genotyping was performed. Large ranges of phagocytosis and extracellular lysis of RBC in vitro, and of half lives of RBC in vivo, were observed. Clearance of RBC coated with monoclonal IgG3 anti-D (BRAD-3) was more rapid in five subjects homozygous for Fcgamma RIIIa-F/F158 than in three subjects expressing the Fcgamma RIIIa-V158 allele (P = 0.024). This effect was not observed, however, for those individuals given polyclonal anti-D. There was also no significant difference in the efficiency of RBC destruction in vitro or of RBC clearance in vivo between the subjects analysed for individual genotypes or alleles or combinations of alleles. In conclusion, the presence of the Fcgamma RIIIa-V158 allele compromised the efficiency of removal of RBC coated with IgG3 anti-D.

Common HLA-B8-DR3 haplotype in Northern India is different from that found in Europe

The aim of this study was to determine whether a common diabetic haplotype, including human leukocyte antigen (HLA)-B8 and HLA-DR3, in Northern India is the same haplotype as the European HLA-B8-DR3 haplotype. DNA samples from Northern Indian subjects selected on the basis of HLA-B8 and HLA-DR3 were tested for microsatellite and single nucleotide polymorphism alleles throughout the major histocompatibility complex (MHC). It was found that the Indian samples represent a conserved haplotype in which all alleles were shared by Indian subjects with HLA-B8 and HLA-DR3, but were different to those that are characteristic of the European 8.1 ancestral haplotype. The Indian and European haplotypes share HLA-B*0801, HLA-DRB1*0301 and HLA-DQB1*02 but differ for subtypes of HLA-Cw*07 and HLA-DRB3 and all central MHC alleles tested. In contrast, Indian subjects selected on the basis of HLA-B58 ( 1-17) and HLA-DR3 shared the same alleles at other MHC loci as have been described in the common Chinese haplotype with HLA-B58/17 and HLA-DR3. A third haplotype, HLA-B50/21 and HLA-DR3, was also found to be highly conserved but shares little in common with the other two HLA-DR3-containing Indian haplotypes.

The genetic basis for the association of the 8.1 ancestral haplotype (A1, B8, DR3) with multiple immunopathological diseases

An individual's major histocompatibility complex (MHC) ancestral haplotype (AH) is the clearest single determinant of susceptibility to MHC associated immunopathological disease, as it defines the alleles carried at all loci in the MHC. However, the direct effects of any of the 150-200 genes that constitute the MHC are difficult to determine since recombination only occurs at defined hotspots. This review concerns the 8.1 AH (HLA-A1, C7, B8, C4AQ0, C4B1, DR3, DQ2), which is carried by most Caucasians with HLA-B8. It is associated with accelerated human immunodeficiency virus (HIV) disease, and susceptibility to insulin-dependent diabetes mellitus (IDDM), systemic lupus erythematosus, dermatitis herpetiformis, common variable immunodeficiency and IgA deficiency, myasthenia gravis and several other conditions. We have mapped susceptibility genes for HIV, IDDM and myasthenia gravis to the central MHC between HLA-B and the tumour necrosis factor or complement genes. Here we consider which of the remaining 8.1-associated diseases are more closely associated with HLA-DR3 and/or DQ2. Several candidate genes in the central MHC have the potential to modulate immune or inflammatory responses in an antigen-independent manner, as is seen in studies of cultured cells from healthy carriers of the 8.1 AH. Hence these genes may act as a common co-factor in the diverse immunopathological conditions associated with the 8.1 AH.

A reassessment of splenic hypofunction in celiac disease

OBJECTIVES

Because there is controversy regarding the prevalence, familial occurrence, and possible factors inducing splenic hypofunction in celiac disease, we have reassessed them in a large series of untreated patients and their first-degree relatives.

METHODS

Pitted red cell counting was used to measure splenic function and the effect that age at diagnosis has on it, while severity of intestinal lesions and nutritional status were estimated by multiple linear regression analysis. Moreover, serum tuftsin activity was assayed by measuring its ability to stimulate phagocytosis of opsonized Staphylococcus aureus.

RESULTS

We found that 32.8% of untreated celiacs and none of their relatives had pitted red cell values in the range of splenic hypofunction (>4%). Only age at diagnosis, but not the other two covariates, was significantly associated with the degree of splenic hypofunction. Tuftsin activity was depressed in celiac disease and this reduction was significantly greater in hyposplenic patients.

CONCLUSIONS

In celiac disease the prevalence of splenic hypofunction is lower than formerly believed. The duration of preexposure to gluten is a crucial factor for the prevalence and severity of this complication that does not affect celiac relatives. In celiac disease splenic hypofunction is accompanied by a reduced phagocyte activity linked to the decreased release of tuftsin.

Defective elimination of C3b/iC3b-coated autologous erythrocytes in patients with primary biliary cirrhosis, alcoholic cirrhosis, and ulcerative colitis

Delayed in vivo elimination of autologous erythrocytes coated with immunoglobulin G has been reported in autoimmune and inflammatory gastrointestinal diseases. Our aim was to elucidate whether impairment of the macrophages was restricted to the Fc receptors of the reticuloendothelial system or whether complement receptors were also affected. We studied elimination by complement receptors of autologous erythrocytes coated with fragments of C3 and C4 in patients with primary biliary cirrhosis, ulcerative colitis, and alcoholic cirrhosis. Impaired function was seen in all patient groups as compared with function in normal subjects, both concerning the mean half-life of the injected cells and the total number of eliminated erythrocytes. Neither of these parameters correlated with the levels of C3 fragments bound to the injected autologous erythrocytes. This is the first report of defective complement receptor function in ulcerative colitis and alcoholic cirrhosis. Immunoglobulin G-dependent elimination of erythrocytes was confirmed to be lowered in all patient groups. The results suggest severe macrophage functional aberrations involving both complement receptors and Fc receptors as the basis of phagocytic defects in autoimmune/inflammatory conditions. In contrast, a general loss of macrophages might cause the functional loss in alcoholic cirrhosis.

HLA-B8,DR3 haplotype affects lymphocyte blood levels

The number of lymphocytes in the blood is constant, pointing to an effective control of circulating lymphocyte values. The mechanisms of this regulation are uncertain, although it is likely that the number of blood lymphocytes is conditioned by hormones, homing factors and cytokines whose production is at least partly restrained by genetic factors. Particularly genetic factors linked to major histocompatibility complex (MHC) appear to be involved. In human beings a decreased number of blood lymphocytes has been described in healthy subjects carrying the Human Leucocyte Antigens (HLA) haplotype HLA-B8,DR3. In the present study, to inquire into the mechanisms of this lymphocyte decreased number, we have performed an analysis of blood subset values in these subjects. When the absolute values of lymphocytes were analysed according to HLA phenotype, HLA-B8,DR3 positive subjects (N = 26) displayed significantly lower values as compared to HLA-B8,DR3 negative ones (N = 282). The analysis of lymphocyte subpopulations performed by flow cytometry in 72 subjects did not show significant changes in lymphocyte subset percentages between HLA-B8,DR3 positive subjects and negative ones. Thus, the decrease of circulating lymphocytes seems to be due to a reduction of cell number affecting all lymphocyte subsets rather than a single cell subpopulation. The analysis of in vitro spontaneous apoptosis performed by flow cytometry in a smaller sample of subjects showed a significant increase of spontaneous apoptosis in lymphocytes from HLA-B8,DR3 positive individuals suggesting a possible explanation for the deviation from normal lymphocyte count observed in these subjects. However it is intriguing that a decreased number of blood lymphocytes can be observed in healthy HLA-B8,DR3 positive subjects but also in autoimmune diseases linked to this haplotype like systemic lupus erythematosus and insulin-dependent diabetes. Furthermore, in our opinion, this finding is to be kept in mind in evaluating hematological parameters in healthy subjects.

Distinct immunologic features of Finnish Sjögren's syndrome patients with HLA alleles DRB1*0301, DQA1*0501, and DQB1*0201. Alterations in circulating T cell receptor gamma/delta subsets

OBJECTIVE

To determine whether there were differences in the circulating T lymphocyte subsets or clinical features of patients with primary Sjögren's syndrome (SS) who were positive for different HLA alleles.

METHODS

Two- and three-color flow cytometry analyses were performed, using a whole blood lysing method.

RESULTS

Patients with SS who had the HLA alleles DRB1*0301, DQA1*0501, and DQB1*0201 had lower levels of circulating V delta 1-positive T cell receptor gamma/delta (TCR gamma/delta) cells and higher levels of circulating CD45RO-positive TCR gamma/delta cells compared with patients with SS who did not have these alleles. The patient subgroup with these alleles also had higher levels of anti-SS-A/Ro and anti-SS-B/La.

CONCLUSION

These results indicate that patients with primary SS may be immunologically divided into subgroups according to their HLA status. These immunologic changes in SS may also be typical of other autoimmune disorders in patients with the HLA-DR3 haplotype.

Genetic susceptibility to severe course of nephropathia epidemica caused by Puumala hantavirus

Nephropathia epidemica (NE) caused by Puumala hantavirus is one type of hemorrhagic fever with renal syndrome (HFRS). There is considerable variability in the clinical severity of NE. Many infections are subclinical but the disease can even be fatal. We questioned whether the wide spectrum in the outcome of NE is dependent, on host-related immunological factors by determining the major histocompatibility complex markers (MHC) in 74 adult patients with NE. Patients with the most severe course of the disease had a very high frequency of HLA B8, C4A*Q0, and DRB1*0301 alleles. HLA B8 was found in all 7 (100%) patients with shock and in 9 of the 13 (69%) patients who required dialysis, versus in only 25 of 74 (34%) in the entire population, and in 14 of 93 (15%) controls. In addition, various other clinical findings pointing to a severe form of NE were found to be associated with these alleles. Interestingly, the same MHC alleles are risk factors for various autoimmune diseases. This is the first study where a certain HLA haplotype is found to be associated with the clinical course of an acute viral disease or acute nephritis.

Genetic predisposition to HIV-1 infection and acquired immune deficiency virus syndrome: a review of the literature examining associations with HLA [corrected]

Researchers have been studying the relationship between host HLA type and the immune response to HIV-1 since early in the AIDS epidemic. Although the literature is replete with suggestions of an association, the exact locus and nature is unclear. This article reviews the current HLA-HIV/AIDS literature, providing a complete summary of all significant associations reported in journal articles (N = 30) between 1982 and 1993. Consistent associations with alleles comprising the haplotype DQ2-DR3-B8-Cw7-A1 and AIDS progression support a genetic component in AIDS progression. DQ1-DR1-B35-Cw4-A11 and DR5 also show consistent associations with HIV/AIDS outcomes, although it is unclear whether they are measuring susceptibility to HIV-1 infection, AIDS progression, or both. The question of whether HLA influences susceptibility to HIV-1 infection remains unanswered, as well-designed studies addressing this topic are lacking. Similarly, further studies are needed to clarify if HLA type is associated with KS. Several issues that complicate across-study comparisons are discussed including heterogeneity of both HLA and AIDS, potential confounding by race or risk group, and other biases which may influence results. In addition, several proposed biologic mechanisms are explored.

T-cell activation in HLA-B8, DR3-positive individuals. Early antigen expression defect in vitro

The HLA-B8, DR3 haplotype is overrepresented in several autoimmune diseases, implying that genes predisposing to these disorders are linked to this haplotype. In the patients affected by these diseases, as well as in healthy HLA-B8, DR3 individuals, various dysfunctions reflecting an impairment of T-cell activation have been found. To better characterize T-cell impairment of HLA-B8, DR3-positive healthy individuals, we analyzed the surface expression of early (CD69) and late (CD71) activation phenotypes. MNC cultures were stimulated with PHA and used for T-cell phenotyping by flow cytometry analysis. The results showed that the percentage of CD69+ T cells was significantly decreased in MNC from HLA-B8, DR3+ subjects. This defect was detected in cell cultures from all subjects studied, but it attained significance only in females in the early hours after stimulation. The difference in CD69 expression between HLA-B8, DR3-positive individuals and -negative ones was not due to differences in CD4 and CD8 ratios in the HLA-B8, DR3 cells that underwent activation, as following activation the pattern of CD4 and CD8 antigen expression was the same in both groups of subjects. Concerning the late antigen CD71, no significant difference in percentage was observed between T lymphocytes from HLA-B8, DR3+ and HLA-B8, DR3- subjects at all the times studied. The analysis of the requirements for CD69 expression has suggested that sustained PKC activation and an increase of intracellular CA2+ could be responsible for TCR/CD3-mediated CD69 induction. Thus, present data suggest a defect in the signal transduction pathway of the TCR/CD3 complex.(ABSTRACT TRUNCATED AT 250 WORDS)

Lupus nephritis in childhood and adolescence

Lupus nephritis in childhood usually presents after the age of 10 years, and presentation under 5 years is very rare. More males (F:M ratio 4.5:1) are affected than in adult-onset cases, but the ratio is the same in prepubertal and pubertal children. The incidence of clinically evident renal disease is greater at onset than in adults (82%), the usual presentation being with proteinuria, 50% having a nephrotic syndrome. Half the children show World Health Organisation class IV nephritis in renal biopsies. Neuropsychiatric lupus is present at onset in 30%, may complicate 50% at some point and remains a major problem. Prognosis has improved greatly over the past 30 years, at least in part the result of immunosuppressive treatment. Treatment of the initial phase may be guided by the severity of the renal biopsy appearances, more aggressive treatment including cytotoxic agents, i.v. methylprednisolone and perhaps plasma exchange, although the value of exchange is not established. Controversy persists as to the most effective cytotoxic treatment in the acute phase, both oral and i.v. cyclophosphamide and azathioprine being used in different units. In the chronic maintenance phase it seems established both clinically and histologically that addition of a cytotoxic agent improves outcome, but again the drug and route of administration are contentious. Azathioprine has the advantage of being safe for pregnancy and not gonadotoxic, whilst i.v. cyclophosphamide has been demonstrated to improve results over prednisolone alone in controlled trials and has advantages in non-compliant patients. No trial comparing the two regimes has been carried out, and one is needed. Today children much less commonly go into renal failure, and the main causes of actual death (15% of patients over 10 years) are now infections and extra-renal manifestations of lupus, principally neurological. Morbidity of the disease and the treatment remain a major problem, especially when treatment exacerbates complications of the disease itself, such as infections, osteonecrosis, thrombosis, vascular disease and possibly neoplasia.

Lymphocyte subset abnormalities, autoantibodies and their relationship with HLA DR types in children with type 1 (insulin-dependent) diabetes and their first degree relatives

Type 1 (insulin-dependent) diabetes mellitus is associated with abnormalities of circulating lymphocyte subsets and autoantibodies. To investigate the prevalence of these in non-diabetic siblings and non-diabetic patients of children with Type 1 diabetes, we analysed T-cell subsets of function and activation in 31 families with an index case of Type 1 diabetes and related these to autoantibodies and HLA DR type. Using two and three colour cytofluorimetry, we studied total and activated (HLA-DR+) CD3+, CD4+, CD8+, lymphocytes and on CD4+ lymphocytes the CD45RA/RO "naive" and "memory" cell phenotypes. Diabetic children (mean duration of disease 3.1 years) had a reduced total lymphocyte count (p < 0.05), their non-diabetic siblings a reduced CD4+ T-helper cell count (p < 0.05), and their parents a reduced percentage and number of CD3+ T cells (p < 0.01 and p < 0.05) compared with age-matched control subjects. Diabetic children, their siblings and parents all had significantly increased levels of activated CD4+ T-helper cells (p < 0.01, p < 0.05 and p < 0.01). In diabetic children and their siblings there was a significant over-expression of the CD45RO "memory" cell marker and significant under-expression of the CD45RA "naive" cell marker, whilst these were normal in the parents. Islet cell antibody positive diabetic children had significantly higher levels of CD45RO-expressing CD4+ lymphocytes than those who were islet cell antibody negative (p < 0.05). Amongst the siblings and parents, possession of HLA-DR4 was associated with lower percentages of CD4+ and higher percentages of CD8+ T cells. These findings extend current knowledge about the role of immunoregulatory CD45RA/RO cells in Type 1 diabetes. In addition, they demonstrate lymphocyte subset abnormalities in unaffected family members, some of which may be influenced by HLA DR alleles.

In vitro cytokine production by HLA-B8,DR3 positive subjects

It is well known that healthy subjects carrying the HLA-B8,DR3 haplotype may show an impairment of immune system, the T cells being the most affected. To gain insight into the mechanism(s) of the impairment displayed by these subjects, efforts have been centered on the study of in vitro cytokine production because of the pivotal role played by these mediators in the activation and control of several immune functions. The available results indicate that the ability to several immune functions. The available results indicate that the ability to produce interleukin-1 (IL-1), IL-2 and the soluble form of its receptor (sIL-2R) is impaired in HLA-B8,DR3 positive healthy subjects. To better characterize the cytokine production capacity of HLA-B8,DR3 positive subjects, we have investigated the pattern of in vitro production of IL-2, sIL-2R, IL-4. IL-6 and gamma-interferon (gamma-IFN) by mononuclear cells from HLA-B8, DR3 positive subjects after phytohaemoagglutinin stimulation. A significant decrease of IL-2, sIL-2R and gamma-IFN production by HLA-B8,DR3 positive subjects was observed. No significant difference was instead found between the HLA-B8,DR3 positive subjects and the negative ones as regards IL-4 and IL-6 production. We suggest that this imbalanced cytokine production may well account for the pattern of immune response that may observed in HLA-B8,DR3 positive subjects, i.e. a normal or increased humoral response in face of a low T cell immune responsiveness.

Prevalence of abnormal thyroid function tests in connective tissue disease

The prevalence of thyroid function tests' abnormalities in 170 patients with various connective tissue diseases (CTD) was examined and compared to a group of 100 age- and sex-matched controls. The overall prevalence of diagnosed thyroid disease was 3.5%. Categorizing the patients into 5 "functional groups" by the concurrent thyroid function test/results showed normal thyroid function tests in 14%, isolated elevated TSH levels with normal T4 and T3 levels in 4% and findings consistent with the laboratory diagnosis of primary hypothyroidism in 3%. The "euthyroid sick syndrome" was evidenced in 54% and elevated T4 levels and/or increased or normal T3 values with normal TSH in 25%. Antimicrosomal antibodies were noted in 12 patients (7%), with the highest incidence in systemic lupus erythromatosus patients (10%). patients with mixed connective tissue disease had significantly (p < 0.0005) higher frequency of hypothyroidism, whereas patients with systemic vasculities had higher frequency of hyperthyroxinemia. In conclusion, CTD patients frequently have abnormal results of one or more of thyroid function tests. Hypothyroidism and hyperthyroidism should be considered when evaluating symptoms and signs in CTD and a significant subset of CTD patients appears to be predisposed to the development of hyperthyroidism.

Fc receptor-mediated signal transduction

Receptors for the Fc domain of IgG (Fc gamma Rs) on leukocytes mediate a pleiotropic response following cross-linking by immune complexes. Signaling events following cross-linking of B and T cell antigen receptors, Fc epsilon RI, and Fc gamma Rs share common elements. In each, signaling is initiated by receptor cross-linking by antigen or immune complexes and results in the activation of src family kinases and ZAP-70-related tyrosine kinases, which associate with members of the receptor complex. Subsequent events include phosphorylation on tyrosine of multiple cellular substrates including phospholipase C gamma 1 and PI3-kinase. The [Ca2+]i flux is an event secondary to phospholipase C gamma 1 activation. Protein tyrosine kinase inhibitors block both early events such as [Ca2+]i flux and the later effects of cytokine release and cellular proliferation.

Human lymphocyte antigens (HLA) and Graves' disease in Turkey

To evaluate the association of HLA types with Turkish patients with Graves' disease, HLA typing, clinical findings, and thyroid antibodies were correlated. The HLA types, clinical findings (ophthalmopathy and age at onset), and thyroid stimulating hormone (TSH) receptor (TRAb) and antithyroid microsomal antibodies (MAb) were analyzed. Seventy Turkish patients with Graves' disease and 306 control subjects were assessed. Serological HLA typing was performed in HLA A, B, C, DR, and DQ loci. There was a significantly increased prevalence of HLA B8, B49, DR3, DR4, and DR10 in Graves' disease. The association of Graves' disease with HLA DR3 was found to be less strong than previously described. The HLA DR4 antigen may contribute to the predisposition of Graves' disease in Turkey. The results suggest that HLA B7, B13, DR7, DQw2, and DQw3 may confer a protective effect for Graves' disease in Turkey. Patients carrying HLA B12, B18, and B44 haplotypes had a tendency to develop the disease at a later age. The difference from the other studies may be the result of the selection of the controls; in part, of the variability in serological typing reagents; and, also, of the rather weak HLA associations with the disease.

The effect of acute alcohol ingestion on Fc-receptor-mediated clearance of IgG-tagged erythrocytes by the reticuloendothelial system in humans

To help elucidate the pathogenesis of bacterial infections in alcoholics we documented reticuloendothelial system (RES) function in 14 healthy adults (9 males, 5 females, age: 22 +/- 2.6 years) prior to and following acute alcohol intoxication. Autologous erythrocytes were labelled with Cr51 isotope, tagged with anti-Rh IgG antibody, and infused into the systemic circulation. Blood samples were drawn at specific time intervals over a 2-h period and the radioactivity in each sample was used to develop computer-generated clearance curves from which half-lives (T1/2) were derived. Each study was carried out in the same individual on two separate occasions at least two weeks apart, once when sober and again one hour after ingestion of an intoxicating amount of alcohol (1 gm/kg over 1 h). Eleven of 14 participants showed no appreciable change in RES clearance capacity following alcohol ingestion. In the remaining three individuals alcohol prolonged the T1/2 by 38%, 38%, and 74% from when sober. These individuals were similar to other participants in terms of age, blood alcohol levels, pre- and postalcohol liver biochemistry, and hematologic and immunologic findings. Two of the three were HLA Dr5 positive, as compared to none of the 11 with unimpaired clearances. The results of this study suggest that perhaps a small subset of the population exists in whom acute alcohol intoxication impairs Fc-receptor-mediated RES clearance of IgG-tagged erythrocytes from the systemic circulation. This depression of RES function could contribute to the increased frequency and severity of bacterial infections reported in some alcoholics.

Tissue distribution of autoantigen specific for primary sclerosing cholangitis

AIM

To investigate the tissue distribution of the autoantigen specific for primary sclerosing cholangitis.

METHODS

A range of normal frozen tissues including nervous system, muscle, uterus, ovary, prostate, pancreas, thyroid, salivary gland, adrenal gland, colon, gall bladder, stomach, jejunum, aorta, skin, kidney, liver, spleen and thymus was sectioned, fixed with acetone, and air-dried. Normal bone marrow and HL60, K562, and U937 cells were cytocentrifuged on to slides, air-dried, and alcohol fixed. Four sera from primary sclerosing cholangitis with high titre antibody (> 1/100) were used to screen the tissues using either two-step or APAAP immunohistochemistry. Normal sera were used as controls.

RESULTS

Positive signal was detected in neutrophils in spleen with three out of four primary sclerosing cholangitis sera while one out of four primary sclerosing cholangitis sera stained spindle cells in the liver. All four sera stained mature neutrophils of the normal bone marrow. Some bone marrow neutrophil precursors (metamyelocytes and myelocytes) were also positive. All other tissues, including HL60, K562, and U937 cells, were negative. Normal sera were negative on all tissues.

CONCLUSION

Antigen specific for primary sclerosing cholangitis seems to be unique to neutrophil polymorphs and is present only after myeloblast differentiation of the myeloid cell line. The antigen may be within the secondary granule of the neutrophil polymorph.

HLA-DR3, DQ2 homozygosity in two patients with insulin-dependent diabetes mellitus superimposed with ulcerative colitis and primary sclerosing cholangitis

Two unrelated young males with the unusual simultaneous presence of insulin-dependent diabetes mellitus, ulcerative colitis and primary sclerosing cholangitis are reported. Both patients manifested homozygosity for the DR3-DQw2 (DQB*0201) HLA genotypes. We believe that homozygosity for this genotype may predispose for this type of multi-organ autoimmune disease.

HLA-B8,DR3 phenotype and the antibody response against Epstein-Barr virus

Antibodies against the viral capsid antigen (VCA) and nuclear antigens (EBNAs) of the Epstein-Barr virus (EBV) were determined in a sample of Sicilian population. A significant correlation was observed between HLA-B8,DR3 phenotype and reduced titres of antibodies to EBNAs, whereas HLA-B8,DR3 positive individuals displayed levels of antibodies to VCA comparable to those of HLA-B8,DR3 negative ones. These results further strengthen the suggestion that HLA-B8,DR3 positive subjects are low responders and that the depth of immune response depends on the fashion of antigenic challenge.

An Fc gamma RIII (CD16)-specific autoantibody from a patient with progressive systemic sclerosis

Polyspecific and organ specific autoimmune diseases are often accompanied by prolonged clearance of immune complexes. In mice, impaired macrophage Fc gamma receptor function may be associated with autoantibody against Fc gamma receptors. To extend these observations to autoimmune human disease, we transformed with EBV peripheral lymphocytes from a patient with terminal progressive systemic sclerosis and screened for clones secreting anti-Fc gamma receptor Ig. A clone, N55, which secretes a high affinity anti-Fc gamma receptor IgG2 antibody was obtained. The Fab fragment of N55 bound to human neutrophils, NK cells, but not to monocytes, consistent with specificity for Fc gamma RIII (CD16). N55 Fab competed weakly for the binding of anti-Fc gamma RIII mAb 3G8 to neutrophils but did not have any effect on staining with the anti-Fc gamma RII mAb, IV.3. N55 Fab did not bind to peripheral monocytes, but did bind to monocytes incubated with TGF-beta (24 h) to induce Fc gamma RIII. The specificity of N55 IgG for Fc gamma RIII was confirmed by ELISA using secreted recombinant Fc gamma RIIA and Fc gamma RIIIB protein to coat microtiter wells. N55 IgG triggered the release from neutrophils of beta-glucuronidase, arylsulfatase and alkaline phosphatase. Such antibody may play a pathogenic role in progressive systemic sclerosis.

In vivo clearance by the mononuclear phagocyte system in humans: an overview of methods and their interpretation

The mononuclear phagocyte system (MPS) is responsible for the elimination of foreign material, effete autologous material and immune complexes. To study the relationship between MPS function and human disease, several test substances have been developed, and used to determine the clearance capacity of the MPS in human subjects in vivo. These test substances and the multitude of factors that influence the elimination of these substances (and complicate the interpretation of the test results) are discussed. Use of these probes has provided important new insights, that may lead to the development of treatment modalities by which MPS function is modified in order to influence disease processes more effectively.

The immune response to hepatitis B vaccine in humans: inheritance patterns in families

We have recently shown that the human antibody response to the hepatitis B virus surface antigen (HBsAg) vaccine is major histocompatibility complex (MHC) associated. In studies of nonresponders to the vaccine, we found an increased incidence of individuals homozygous for human histocompatibility leukocyte antigen (HLA) proteins associated with the extended (conserved) haplotype [HLA-B8,SC01,DR3]. In later prospective vaccination trials, we showed that none of five individuals homozygous for this haplotype developed more than 1,300 radioimmunoassay (RIA) units of antibody (mean, 467 RIA units), while all heterozygotes made at least 2,500 RIA units (mean antibody level, 15,608 units). Our results suggested that [HLA-B8,SC01,DR3] lacks an immune response gene for HBsAg, and that response is inherited in a dominant fashion. To provide further evidence for this hypothesis, we have now analyzed the results of HBsAg immunization in families. 43 members of 10 families were immunized with the hepatitis B vaccine, including seven families where at least one member bore the haplotype [HLA-B8,SC01,DR3], and three families where one member had already received, but failed to respond to, the vaccine. In two of these three families, the presence of [HLA-B8,SC01,DR3] was subsequently found. Of nine MHC-identical sibling pairs in the study, both members of eight pairs had similar antibody responses (five nonresponder and three responder pairs). In all families with such sibling pairs, including the discordant pair, rank-ordering members by antibody level demonstrated that no relative's value came between the sibling pair values. Furthermore, of nine [HLA-B8,SC01,DR3]-haplotype-homozygous individuals, six were nonresponders, and two others had only low-normal responses. [HLA-B8,SC01,DR3]-heterozygous family members always had higher levels of antibody than their homozygous relatives. Linkage analysis of nonresponse to HLA haplotypes revealed a maximum likelihood LOD (logarithm of the odds) score of 6.3 at a recombination fraction of 0.1. The MHC association with lack of antibody response to HBsAg was not seen with tetanus immunization, where 1 of 20 HBsAg responders and 1 of 21 poor or nonresponders had tetanus titers of less than 1:512; both tetanus nonresponders were [HLA-B8,SC01,DR3] heterozygotes. Our results indicate that: (a) response to the HBsAg vaccine is MHC linked, and inherited in a dominant fashion; (b) an abnormal or missing immune response (Ir) gene for HBsAg is a characteristic of most examples of the extended haplotype [HLA-B8,SC01,DR3]; and (c) other haplotypes also have abnormal or missing Ir genes for HBsAg.

Defective Fc receptor-mediated clearance in patients with primary biliary cirrhosis

Fc receptor-mediated clearance of immunoglobulin G-coated autologous erythrocytes was studied in patients with primary biliary cirrhosis (n = 14), alcoholic liver cirrhosis (n = 5) and healthy reference individuals (n = 14). The mean half-life of the sensitized erythrocytes was significantly prolonged in patients with primary biliary cirrhosis (85 +/- 25 minutes; P less than 0.001) compared with the corresponding value in patients with alcoholic cirrhosis (16 +/- 2 minutes) and healthy reference individuals (20 +/- 5 minutes), respectively. No correlation between clearance rate and age, liver histopathology, or serum levels of bilirubin, aminotransferases, immunoglobulin G, immunoglobulin A, and Clq binding or C3-containing immune complexes was found. The results presented here indicate a profound disturbance of Fc receptor-mediated immune clearance function in patients with primary biliary cirrhosis.

Soluble interleukin-2 receptor levels in patients with dermatitis herpetiformis

To determine the role of T-cell activation in dermatitis herpetiformis (DH), soluble IL-2R levels were measured by enzyme-linked immunosorbent assay (ELISA) in the sera of 30 patients with DH. Levels of this shed receptor are considered to be a measure of in vivo T-lymphocyte activation, and are elevated in the sera of many patients with inflammatory and immune-mediated diseases. Fifteen of the thirty (50%) patients with DH had elevated levels of soluble IL-2R compared to one of 31 (3%) healthy HLA-B8 or HLA-DR3 control subjects (p less than 0.00001) and one of 10 (10%) healthy non-HLA-B8/-DR3 subjects (p less than 0.0018). In addition, the mean soluble IL-2R level in the patients with DH (744 +/- 381 U/ml) was also significantly higher than that seen in 31 healthy HLA B8 or HLA DR3 individuals (388 +/- 160 U/ml, p = 0.0001) and 10 healthy non-HLA-B8/DR3 individuals (397 +/- 201 U/ml, p = 0.002). Only two of the 30 patients with DH had active skin lesions at the time of serum sampling, one of whom had elevated levels of IL-2R. Measurement of soluble IL-2R levels in sequential serum samples, available in four patients with DH at times of active and inactive skin disease, demonstrated a temporal association between soluble IL-2R level elevations and active skin disease in two patients and no association in two patients. In one patient a marked elevation in soluble IL-2R levels occurred with the onset of gastrointestinal symptoms, which decreased by 14% with institution of a gluten-free diet. In order to determine if soluble IL-2R levels are related to the mucosal immune response, the IL-2R levels were compared to the level of IgA antibodies directed against the dietary antigen beta-lactoglobulin. Ten of eleven (91%) patients with circulating IgA anti-beta lactoglobulin antibodies were also found to have elevated levels of IL-2R. In contrast, in the patients with no detectable IgA anti-beta lactoglobulin antibodies, only four of 16 (25%) had elevated levels of IL-2R (p = 0.001). Because IL-2R levels are not related to activity of the skin disease in patients with DH but are associated with the presence of IgA antibodies against the dietary antigen beta-lactoglobulin, these results suggest that some of the T-cell activation commonly present in DH reflects an ongoing immune response in the gastrointestinal tract.

An improved method to study complement receptor-mediated function of the fixed macrophage system in vivo

A method to coat unsensitized erythrocytes with fragments of C3 and C4 using autologous serum, in order to study complement receptor-dependent function of the fixed macrophage system, is presented. After incubation with serum under optimal conditions, at least 90% of the cells had C3b/iC3b deposited on the surface, with an average of 20 x 10(3) molecules per cell. Elimination of the coated cells by the fixed macrophage system was studied in 12 normal subjects. With a dose of 4.5 x 10(8) red cells injected, 75% of the cells were eliminated with a half-life of approximately 2.4 +/- 0.3 min (n = 7). In subjects receiving ten times more cells, there was a rapid decrease in the amount of C3-coated cells, reaching a nadir with 85% remaining for 4-6 min, after which there was a gradual release of cells for another 20 min (n = 5). In absolute numbers, 3 x 10(8) of labeled cells were eliminated regardless of the dose injected. The coating procedure presented here is simple, does not introduce heterologous blood components and makes it possible to control the amount and the degree of fragmentation of the C3 and C4 deposited on the erythrocyte surface.

DNA sequence analysis and restriction fragment length polymorphism (RFLP) typing of the HLA-DQw2 alleles associated with dermatitis herpetiformis

Dermatitis herpetiformis (DH) is a blistering autoimmune skin disease associated with a 95-100% incidence of the HLA class II antigen HLA-DQw2. Although the precise role of this antigen in the pathogenesis of DH is unclear, one theory proposes that patients with DH possess a molecularly unique subtype of the HLA-DQw2 antigen that causes immune abnormalities eventuating in the clinical manifestations of DH. To test this hypothesis, we performed DNA sequence analysis on the highly polymorphic HLA-DQB1 and HLA-DQA1 loci of eight patients with dermatitis herpetiformis. All DQB1 alleles sequenced were identical to the previously described HLA-DQB*0201 allele from HLA-DQw2 normal subjects. In addition, DQA1 alleles sequenced were identical to those alleles previously associated with HLA-DQw2 (DQA*0201, DQA*0501). These data document that although HLA-DQw2 appears to be a necessary element in the pathogenesis of DH, the development of DH is not dependent on the presence of a unique HLA-DQw2 antigen. HLA-DQ allelic typing by restriction fragment length polymorphism analysis of PCR-amplified HLA-DQA1 and HLA-DQB1 fragments was also performed in ten patients with DH to determine the allelic distribution among both HLA-DR3 (eight patients) and non-DR3 (two patients) DH patients. At the HLA-DQ beta chain locus, all patients possessed the DQB1*0201 allele. At the HLA-DQ alpha chain locus, all HLA-DR3 patients and one non-DR3 patient displayed a pattern consistent with the DQA1*0501 allele, whereas one non-DR3 patient displayed a pattern consistent with the DQA1*0201 allele. These data document that patients with DH do not express a unique HLA-DQw2 heterodimer, that the HLA-DQw2 molecules present in patients with DH have no DNA sequence differences from those found in normal HLA-DQw2 subjects and therefore that susceptibility to DH is not due to a unique HLA-DQw2 molecule.

Fc receptor function and circulating immune complexes in gluten sensitive enteropathy--possible significance of serum IgA

The capacity to clear IgG containing immune complexes from the circulation was studied in patients with coeliac disease (n = 13), dermatitis herpetiformis (n = 8), and coeliac disease with concomitant serum IgA deficiency (n = 4). A small group of patients with active ulcerative colitis (n = 4) was included as a bowel disease control group. Clearance was estimated by measuring the disappearance rate of a bolus dose of intravenously injected IgG coated autologous erythrocytes. The mean T1/2 of clearance was prolonged in both coeliac disease (86 (24) minutes) and dermatitis herpetiformis (111 (35) minutes), compared with healthy subjects (20 (5) minutes) and coeliac patients with concomitant serum IgA deficiency (T1/2 = 17 (6) minutes). Patients with ulcerative colitis had a prolonged clearance, with a T1/2 of 195 (63) minutes. Values of circulating immune complexes were measured by four assays; C1q binding and C3, IgG, and IgA containing immune complexes. C1q binding immune complexes were detected only in IgA deficient gluten sensitive enteropathy. Patients with coeliac disease and dermatitis herpetiformis had higher values of C3, IgG, and IgA containing immune complexes than control subjects and serum IgA deficient patients with coeliac disease. The clearance rate was inversely correlated to the amount of immune complexes for the subgroups of gluten sensitive enteropathy.