Identification, characterization, and quantitation of soluble HLA antigens in the circulation and peritoneal dialysate of renal patients

Soluble Human Leukocyte Antigen class I antigen and interleukin-12 in hepatectomized patients

BACKGROUND

Interleukin-12 (IL-12) has been shown to enhance the cytotoxic activity of NK cells and CTL. IL-12 also acts as a growth factor for activated NK, T and NKT cells. The soluble HLA class I (sHLA-I) has been reported to bind a killer-cell inhibitory receptor, which is expressed on the NK cell, and its signals inhibit NK cell-mediated cytotoxicity. Effects of fresh frozen plasma (FFP) on post-operative immune status have not yet been completely examined.

METHODS

Thirty consecutive patients taking a hepatectomy were enrolled. The levels of IL-12 and sHLA-I were examined by enzyme-linked immunosorbent assay.

RESULTS

The rate of complication after hepatectomy in the FFP-administered patients was higher than that in patients without FFP administration (P = 0.0358). Decreased IL-12 levels after surgery in patients without FFP administration recovered to the preoperative state earlier than those in patients with FFP administration (P < 0.05). The levels of sHLA-I in the FFP-administered patients were higher than those in the patients without FFP administration (P < 0.05).

CONCLUSIONS

Administration of FFP, which contains sHLA-I, affected the levels of sHLA-I after hepatectomy. Both high levels of sHLA-I and low levels of IL-12 could attenuate NK activities after hepatectomy, especially when FFP would be administered.

Peptides derived from a soluble molecule of the human leukocyte antigen (HLA) class I cause apoptosis in gastric cancer cell lines

We have reported that the levels of the soluble molecule of the human leukocyte antigen class I (sHLA-I) in patients with advanced gastric cancer were significantly lower than those in patients with cancer in the early stages. However, the effect of sHLA-I on gastric cancer cells has not been elucidated. Using human gastric cancer cell lines, MKN28, MKN45, and MKN74, we evaluated the effects of sHLA-I on cell growth, DNA synthesis, and apoptosis induction. Three types of synthesized peptides derived from HLA-I were also examined for their capacity to induce apoptosis. sHLA-I and a synthesized peptide, nos. 220-232 of the alpha3 domain of HLA-B7, caused cell growth inhibition by inducing apoptosis in human gastric cancer cells. This peptide also inhibited the in vivo growth of cancer dissemination caused by an intraperitoneal injection of MKN45 into severe combined immunodeficient mice. In conclusion, sHLA-I and the peptides derived from HLA-I cause apoptosis in human gastric cancer cell lines.

Soluble HLA measurement in saliva and cerebrospinal fluid in Caucasian patients with multiple sclerosis: a preliminary study

Background

Measurement of soluble HLA in body fluids has a potential role in assessing disease activity in autoimmune disorders.

Methods

We applied a solid phase, enzyme-linked immunoassay to measure soluble HLA class I (sHLA-I) and class II (sHLA-II) molecules in the saliva and cerebrospinal fluid (CSF) in 13 untreated patients with relapsing-remitting form of multiple sclerosis (MS). For comparison purposes, we also studied saliva from 53 healthy subjects.

Results

Saliva from normal controls had detectable sHLA-I levels in 41 of 53 individuals studied, with values ranging from 9–100 ng/ml (mean = 41 ± 2.8 ng/ml). sHLA-I was undetectable in the saliva in 11 of 13 MS patients, and in none of the CSF specimens. In contrast, mean sHLA-II concentration in the saliva of MS patients was significantly increased compared to controls (386 ± 52 unit/ml vs. 222 ± 18.4 unit/ml, t = 8.68, P < 0.005). The mean CSF sHLA-II level (369 ± 16 unit/ml) was equivalent to the mean sHLA-II concentration measured in saliva (mean = 386 ± 52 unit/ml) (P = 0.7). In patients with brain magnetic resonance imaging (MRI) enhancing lesions (n = 5), reflective of more active disease, CSF sHLA-II averaged 356 ± 26 unit/ml compared to 380 ± 51 in saliva. Similarly, in patients with non-enhancing lesions (n = 8), CSF sHLA-II averaged 377 ± 18 unit/ml compared to 390 ± 77 unit/ml in saliva. Thus, the mean sHLA-II concentration in saliva and CSF was essentially equivalent for MS patients with or without enhancing plaques.

Conclusion

Our data suggest that the measurement of soluble HLA in saliva, specifically sHLA-II, correlates with the level found in the CSF. Therefore, if sHLA correlates with disease activity in MS, as has been proposed, saliva measurements provide a noninvasive correlate of CSF measurement.

Soluble HLA Class I and Class II Molecules in Relapsing-Remitting Multiple Sclerosis: Acute Response to Interferon-β1a Treatment and Their Use as Markers of Disease Activity

During relapses in relapsing-remitting multiple sclerosis (RRMS), serum soluble HLA class I surface antigen (sHLA-I) levels are reported to either decrease or remain unchanged, whereas serum sHLA-II levels increase. Interferon-beta1b therapy was recently reported to increase serum sHLA-I in RRMS. In the present prospective study, solid-phase enzyme-linked immunosorbent assay was used to measure sHLA-I and sHLA-II in the sera of 21 RRMS patients during a clinical exacerbation, and then six weeks after treatment with high-dose interferon-beta1a (IFN-beta1a). Pretreatment serum sHLA-I was significantly lower in patients than in normal controls (P < 0.0005). Pretreatment sHLA-II was also significantly lower than in normal controls (P = .003) unless enhancing MRI lesions (objectified relapse) were present; then sHLA-II levels were similar to normal controls (relative increase). Six weeks after initiation of IFN-beta1a treatment, a significant increase in serum sHLA-I was observed in all 21 RRMS patients (P < .0005). Conversely, serum sHLA-II decreased significantly after treatment in the entire patient group (P < .0005). The acute effect of IFN-beta1a on serum sHLA-I and sHLA-II was observed to be the opposite of that occurring during RRMS relapses. Monitoring of both sHLA-I and sHLA-II appears necessary if these molecules are to be developed as RRMS activity markers.

Clinical significance of soluble form of HLA class I molecule in Japanese patients with pancreatic cancer

In recent studies a soluble form of human leukocyte antigen class I (sHLA-I) has been found in blood, urine, ascitic fluid, and various other tissues. Research has been focused on the role of sHLA-I in the induction of immunotolerance in organ transplantation. To examine the role of sHLA-I in the immune system of patients with malignancy, we examined serum sHLA-I levels in patients with pancreatic, biliary, hepatic malignancy, and other diseases. We examined sHLA-I levels in the sera of patients with pancreatic cancer (n = 19), benign biliary disease and chronic pancreatitis (n = 20), hepatocellular carcinoma (n = 51), gallbladder cancer (n = 6), cholangiocellular carcinoma (n = 6), and in normal controls (n = 22), using enzyme-linked immunosorbent assay (ELISA). In patients with pancreatic cancer we also analyzed the relationship between sHLA-I and CA19-9, and the specificity and sensitivity of sHLA-I. When patients with acute or chronic hepatitis were excluded from analysis, the mean sHLA-I level in patients with pancreatic cancer was significantly higher than that of normal controls (p < 0.01) and patients with benign disease (p < 0.01), hepatocellular carcinoma (p < 0.01), gallbladder cancer (p < 0.05), and cholangiocarcinoma (p < 0.05). We determined a serum sHLA-I cutoff level for normal controls of 2000 ng/ml; serum levels of sHLA-I were higher than the cutoff in ten patients with pancreatic cancer, and serum levels of CA19-9 were lower than 37 IU/l in 9 of 14 patients; sensitivity and specificity were 88.2% and 85.5%, respectively. Serum levels of sHLA-I in pancreatic cancer patients were higher than in the other diseases, although we found that pancreatic cancer cell lines did not produce the sHLA-I. The evaluation of serum sHLA-I levels could have clinical significance in pancreatic cancer.

Soluble HLA in human body fluids

There is a growing body of information about the soluble forms of HLA in serum but there are only a few reports discussing sHLA in other body fluids. We quantitated sHLA-I and sHLA-II concentrations in sweat, saliva and tear samples from five normal individuals with known HLA-phenotypes. We also studied sweat samples from an additional 12 normal nonphenotyped subjects, as well as in CSF of 20 subjects with different illnesses, using solid phase enzyme linked immunoassay. Sweat, saliva and tears from normal subjects were found to contain very low or nondetectable amounts of sHLA-I. In contrast, sHLA-II molecules were found in each of these body fluids, although, with considerable variation between individuals. The presence of sHLA-II in saliva was further confirmed by Western-blotting. It was observed that sHLA-II having molecular mass of 43,900 and 18,100 daltons was comparable with that found in serum from normal individuals. In addition, no association of sHLA-II levels with allospecificities in either body fluid or in serum was apparent. The results of CSF sHLA concentrations in different diseases were as follows: (1) High CSF SHLA-I levels were measured during viral encephylitis (n = 3), while none of these patients contained sHLA-II in CSF; (2) The levels of sHLA-II, but not sHLA-I were elevated in CSF of patients during seizure (n = 6) and of patients with neonatal hepatitis (1 of 2) or with connective tissue disease accompanied with viral infection (n = 2); (3) No CSF sHLA-I or sHLA-II could be detected at polyneuropathy (n = 2), or in patients with syphilis (n = 3), or leukemia (n = 2) with evidence of neurologic involvement of central nervous system. Taken together, it may be concluded that the presence of sHLA in several body fluids is physiologically normal. It appears that sHLA-II is the predominant class of HLA molecules present in different body fluids. We propose that the system responsible for sHLA-II production in various body fluids must involve different mechanisms than those responsible for sHLA-I synthesis in serum.

Soluble HLA-I in rheumatic diseases

OBJECTIVE

To study serum levels of Class I soluble HLA (sHLA-I) in patients with systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), polymyositis or dermatomyositis (PM/DM) or scleroderma and to assess the possible influence of ethnic factors on concentration in each disease group.

METHODS

Solid-phase enzyme linked immunoassay was used to measure sHLA-I in the serum of 385 patients with varied ethnic backgrounds (American-Caucasians, African-Americans, Georgian-Caucasians) with rheumatic diseases. Studies on patients were compared to similar measurements of 189 healthy individuals.

RESULTS

Mean sHLA-I levels were significantly higher in patients with SLE than those observed in healthy individuals or other rheumatic diseases. Highest concentrations were present in Georgian-Caucasian patients with SLE. American-Caucasian patients with RA or scleroderma had higher sHLA-I levels than normal Caucasian individuals. The majority of patients with PM/DM in all ethnic subgroups were low secretors of sHLA-I.

CONCLUSION

Mechanisms underlying the secretion of sHLA-I appear to differ among the rheumatic diseases studied and various ethnic groups. These genetic differences in sHLA-I secretion could be associated with ethnic and pathophysiologic differences among these rheumatic diseases.

Serologic allogeneic chimerism

BACKGROUND

At least some transplanted livers secrete soluble human leukocyte antigens (sHLA) of donor phenotype into the body fluids of recipients. The individuals in whom this phenomenon occurs are by definition serologic allogeneic chimeras. Because an allogeneic transplanted liver may induce tolerance to itself and other organs in animals of the donor strain, and because maintenance of a soluble antigen in the circulation of any animal in sufficient quantity for a sufficient period generally leads to tolerance, this phenomenon may be biologically important. This study was performed to determine how common this phenomenon is and whether it occurs after transplantation of organs other than the liver.

METHODS

We studied 445 serum samples obtained from transplant recipients (liver, n=12; kidney, n=18; and heart, n=8) before and at various intervals after transplantation. All patients studied had allografts that had functioned for more than 1 year. We used an enzyme-linked immunosorbent assay to quantitate sHLA-A2 and sHLA-A1/A3/A11 (as a cross-reacting group). Donor and recipient combinations were selected in which measurable allotypes in donors were not present in recipients. In some instances, an additional allotype was present in a recipient but not in a donor.

RESULTS

All liver transplant recipients had detectable donor sHLA in their serum samples after transplantation. In 72% of kidney and 50% of heart transplant recipients, donor sHLA was found persistently in serum samples obtained after transplantation. Interestingly, all heart transplant recipients of HLA-A3, but none of HLA-A2, had detectable donor sHLA in their serum samples, a finding that may be due to technical reasons. High and stable serum concentrations of donor sHLA characterize long-term stable allograft function.

CONCLUSIONS

Donor sHLA is produced by all transplanted livers, most transplanted kidneys, and at least half of (but probably more) transplanted hearts. The hypothesis that donor sHLA may be tolerogenic to liver transplants can be expanded to include kidney and heart transplants.

Peripheral blood mononuclear cell sonicates as an alternative to irradiated allogeneic cells to stimulate a mixed lymphocyte reaction and to enumerate CD69+ alloreactive T cells

An alloreactive reaction similar to that occurring during GvHD can be generated in a mixed lymphocyte culture. The presence of both stimulator and responder cells in these cultures makes the identification and enumeration of alloreactive cells difficult and unreliable. We describe the use of PBMC sonicates as an alternative to the standard MLC method to stimulate an allogeneic reaction. Using combinations of autologous or allogeneic PBMC sonicates, we showed that the lymphocyte proliferative response to cell sonicates was comparable to the response using irradiated cells. The proliferative response was concentration dependent and reached maximum levels at day 6. Both irradiated cells and PBMC sonicates induced significantly lower responses when the stimulating cells were partially HLA-DR matched rather than completely mismatched. Alloreactive T cells stimulated with sonicates were enumerated by the flow cytometric detection of CD69 or CD25. In HLA-mismatched cultures, approximately 7% of CD3+ T cells were CD69+ or CD25+, suggesting alloreactivity. Although there was a significant correlation between the expression of these activation markers and lymphocyte proliferative responses, significant individual variations in the results of these two assays were observed. The results in this study demonstrate the potential of using PBMC sonicates instead of irradiated lymphocytes for the study and identification of alloreactive cells at the cellular and molecular level.

Soluble HLA class I antigens in patients with type I diabetes and their family members

Our objective was to study a possible contribution of MHC genes to S-HLA-I secretion in patients with Type I diabetes. Quantitatively, we used a highly sensitive enzyme-linked immunoassay to measure S-HLA-I in the serum of a total of 39 patients with Type I diabetes, as well as 36 kinships of 12 diabetic patients and 82 normal individuals with known HLA-phenotypes. S-HLA-I levels were abnormally elevated in patients or their non-diabetic relatives compared to normal controls (p < 0.0009). No complete HLA-haplotype had been identified to be correlated with high or low S-HLA-I secretion. Only the HLA-A23 or A24 (splits of HLA-A9) positive individuals sera were found to contain high S-HLA-I concentrations in all populations studied. The difference in S-HLA-I levels of HLA-A24 patients (n = 4) or their HLA-A24 positive non-diabetic relatives (n = 10) to the group of HLA-A24 normal controls (n = 15) was statistically highly significant (p < 0.0005 and p < 0.0009, respectively). The results suggests that HLA-A24 may confer additional independent risk for the disease expression in male children but not in female siblings. Nevertheless, the data implies that the patients or their non-diabetic relatives carrying the HLA-A24 have increased risk of developing ICA associated with high S-HLA-I levels compared to HLA-A24 negative probands or their kinships with low levels of S-HLA-I. This effect occurred irrespective to other diabetes related HLA-DR alleles. In summary, the results show a pronounced genetic heterogeneity of Type I diabetes with MHC control of the expression of S-HLA-I and possible involvement of hormonal factors that might potentiate a specific synthesis of S-HLA-I. The findings have implications for identifying individuals with a possible risk for developing the disease.

Soluble histocompatibility class I antigens and beta 2-microglobulin in pregnant females and cord blood samples

Pregnancy can be considered a successful transplantation of allogeneic paternal tissue to the mother. Soluble HLA class I serum levels have been found to increase during solid organ rejection episodes and during graft-versus-host disease after bone marrow transplantation. We wished to determine whether significant changes in sHLA class I and beta 2-microglobulin light chain levels occurred during pregnancy, because these may reflect adaptive changes permitting the acceptance of the fetal graft. Serum samples were obtained from women at different stages of pregnancy and in the postpartum period. Cord blood samples and serum samples from nonpregnant female and male controls living in the same geographic area in Southern Chile were also studied. The levels of sHLA class I heterodimers were determined by an ELISA sandwich technique; beta 2-microglobulin levels were measured by MEIA IMX-Abbott. There was a significant elevation of sHLA class I levels in the first 2 trimesters of pregnancy, followed by a significant drop below normal levels at the end of pregnancy, with normalization in the post-partum period. beta 2-microglobulin levels did not change significantly during pregnancy and did not correlate with sHLA class I levels. In cord blood samples, sHLA class I levels were lower and beta 2-microglobulin levels higher than those of adult controls and of mothers at the time of delivery. The variations in sHLA class I levels during pregnancy may reflect or contribute to immunoregulatory events related to the acceptance of the fetal graft.

Serum and urine soluble HLA class I antigen concentrations are increased in patients with hemorrhagic fever with renal syndrome

OBJECTIVES

In order to evaluate the association between the Hantaan virus-induced cellular-immune response and clinical severity in patients with hemorrhagic fever with renal syndrome (HFRS).

METHODS

We serially measured the serum (n = 16) and urine (n = 6) concentrations of soluble HLA class 1 antigen (sHLA-l) and clinical powameters in patients with HFRS.

RESULTS

Serum sHLA-I concentrations in patients with HFRS were significantly higher than those in controls throughout all clinical phases (p < 0.01). The highly elevated Serum sHLA-I concentrations peaked in the oliguric phase and declined gradually through the phases of HFRS. Serum sHLA-l concentrations in patients with hypotensive episode were higher than in those without the episode (5,85 +/-2,184 vs. 2,389 +/- 860 ng/ml in oliguric phase, 4.11 +/- 1,952 vs. 1,502 +/- 592 ng/ml in diuretic phase, p < 0.05), and serum sHLA-l levels showed a significant correlation with blood WBC count (r = 0.75 in the febrile and hypotensive phase, p < 0.01) and serum creatinine concentrations (r = 0.64 in the oliguric phase, p < 0.01), respectively, Urine sHLA-I levels in the oliguric phase were significantly higher than those in the diuretic phase (390 +/- 155 vs. 214 +/- 45 ng/mg Cr, p < 0.05) and urine sHLA-I levels are associated with severe illness in patients with HFRS. The higher serum sHLA-I are associated with severe illness in patients with HFRS. The persistent elevation of serum sHLA-I during all phases of HFRS might be related to increased production due to prolonged cellular immunologic stimulation by the Hantaan virus rather than decreased excretion of sHLA-I through the kidney.

CONCLUSION

We suggest that the serum and urine sHLA-I concentrations can be used as a stable and objective parameter for monitoring clinical severity and renal dysfunction in patients with HFRS.

Quantification of serum-soluble HLA class I antigens in patients with gastric cancer

The amount of sHLA-I in serum was examined in 74 patients with gastric cancer and 15 normal healthy controls. For mAbs, W6/32 specific for HLA-A, -B, -C, and biotin IOT2 specific for HLA class I associated with beta 2 microglobulin, were used to determine the values of sHLA-I using an ELISA. The patients in stage-IV gastric cancer showed lower values of sHLA-I (445.4 +/- 247.1 ng/ml) than those in stage I (725.9 +/- 575.8 ng/ml), stage II (752.8 +/- 255.0 ng/ml), and normal controls (868.9 +/- 715.0 ng/ml) (P < 0.05). In analysis of the patients with HLA-A24, the allele that has been reported to secrete more sHLA-I than other alleles, the results were nearly the same. These results suggest that the secretion of sHLA-I is low in patients with very advanced cancer. However, there was no correlation between the sHLA-I level and the metastasis or prognosis in longitudinal studies in 11 patients.

Quantitation and characterization of plasma HLA in neonates of different gestational ages

The functional significance of plasma HLA class I antigens is unclear. They are thought to have an immunomodulatory role and be tolerogenic in transplant settings including the materno-fetal semi-allograft. There is, however, no available data on the concentrations of soluble HLA class I antigens in fetuses or newborns. We therefore determined plasma HLA class I antigen levels in 93 neonates born at different gestational ages and compared them to those in 66 healthy adults. The mean plasma HLA concentration in cord blood obtained from these neonates (0.30 +/- 0.15 microgram/ml, mean +/- SD) was significantly lower (p < 0.0001) than in the adults (0.77 +/- 0.44 microgram/ml). No correlation between the plasma HLA levels and the gestational ages of the neonates was detected. Characterizing the plasma HLA class I antigens by immunoprecipitation and immunoblotting, four different molecular weight forms, 44, 39, 36 and 34 kDa, were recognized. Their distribution in neonates was not different from that in adults. Since the circulating leukocytes are a probable source of plasma HLA class I antigens, we measured the surface HLA expression on leukocytes in 4 neonates and 4 adults by immunofluorescent flow cytometry. The fluorescence intensities on neonatal granulocytes and lymphocytes were 50% of those on corresponding adult cells. This finding suggests that the reduced HLA expression by neonatal leukocytes may be partially responsible for the lower concentration of HLA class I antigens in neonatal plasma.

Soluble HLA class I in the serum of transplant recipients

BACKGROUND

Soluble HLA, Class I (S-HLA-I) has been found in serum, plasma, body fluids, peritoneal dialysates, and urine. S-HLA-I may be a product of membrane shedding, proteolysis, and/or alternate gene splicing. Previous assays to quantitate S-HLA-I were cumbersome, required radioisotope labeling procedures, or the purification of Class I antigen preceding antigen quantitation. The authors developed a solid-phase, enzyme-linked immunoassay that can be used to quantitate S-HLA-I and to study its relevance in transplantation.

METHODS

A solid-phase enzyme-linked immunoassay employing monoclonal anti-Class I to catch S-HLA-I present in plasma and peroxidase-labeled monoclonal anti-beta 2-microglobulin (B2M) to quantitate bound S-HLA-I was employed. Values were correlated with rejection and infection episodes. Pre and postoperative determinations were made from the sera of liver, heart, and kidney recipients. Size chromatography was used to compare the molecular weight of S-HLA-I from baseline and peak serum concentrations obtained during rejection episodes (2 liver, 1 heart, 1 kidney), and from 1 kidney recipient with a wound infection.

RESULTS

All 9 liver recipients and 12 heart recipients demonstrated a fall in S-HLA-I, or very low initial values, for the first 10 days and then a progressive increase in values substantially above preoperative concentrations. Values from renal recipients were more variable. There were temporary increases in S-HLA-I preceding or during 16 of 20 (80%) biopsy-proven rejections (all reversible), and in 9 of 11 (83%) episodes of infection (bacterial, viral, and fungal). In heart and liver rejection, as well as the wound infection, the sera contained increased S-HLA-I, which was almost all of the same molecular weight (approximately 52,000 daltons). In serum from the one patient with renal rejection, two additional S-HLA-I peaks occurred, one with a molecular weight near 1,000,000 daltons and the second at a molecular weight approximately 11,000 daltons suggesting cellular breakdown of the donor organ.

CONCLUSION

In summary, different patterns of S-HLA-I concentrations occur after kidney transplantation. Most liver and heart recipients reached a steady state higher than preoperative levels. Transient increases in S-HLA-I occurred with rejection and infection. In one severe rejection episode, larger and smaller fractions of S-HLA-I were detected and may represent cell membrane breakdown.