Cold case: COVID-19-triggered type 1 cryoglobulinemia.

A 42-year-old male was referred to the internal medicine department because of renal failure and persistent malaise after a recent SARS-CoV-2 infection. Blood results showed anemia and severe renal insufficiency (hemoglobin of 10.3 g/dL and a creatinine of 2.19 mg/dL). Additional tests revealed a type I cryoglobulinemia with a cryoprecipitate composed of dual IgM (kappa and lambda). Further investigations on the cryoprecipitate revealed that the immunoglobulins were directed against SARS-CoV-2 antigens. In the meanwhile, our patient noticed improvement of his symptoms accompanied by resolution of laboratory abnormalities. Three months later, the cryoglobulin could no longer be detected.Type 1 cryoglobulinemia is usually associated with lymphoproliferative disorders and is characterized by various symptoms caused by cryoprecipitates occluding small blood vessels. This is, to our knowledge, the first case of type I cryoglobulinemia with proven precipitation of SARS-CoV-19 antibodies. COVID-19 induced cryoglobulinemia appears to have a mild disease course and to be self-limiting upon viral clearance.

Determination of acceptable HLA mismatches in highly sensitized patients by soluble HLA class I ELISA inhibition.

BACKGROUND: Acceptable HLA mismatches for highly sensitized patients are determined so as to increase their chances of receiving transplants. The disadvantage of the current procedures is that the antibody reactivity of the patients' sera is tested against HLA antigens expressed on cells or HLA antigens isolated from cell lysates. Therefore, two (homozygous for HLA-A and -B) to four (heterozygous for HLA-A and -B) different HLA class I antigens are present in the test. This might cause reactivity toward nonacceptable mismatches to mask the determination of acceptable mismatches. METHODS: Recently we observed that the detection of soluble HLA class I antigens is inhibited by HLA-specific antibodies. In the present study, inhibition of soluble HLA-specific ELISAs (anti-soluble HLA-A2, -B7, -B12) was evaluated as a tool used to determine acceptable mismatches. The results were compared with current determination of acceptable mismatches (which is by complement-dependent cytotoxicity and/or fluorescence-activated cell sorter analysis). RESULTS: In the case of acceptable mismatches determined by conventional methods, sera from the patients were not interfering in these ELISAs, whereas in the case of nonacceptable mismatches (thus specific antibodies), significant inhibition was observed in most instances. Among the nonacceptable mismatches, the test showed significant inhibition in 20 of 24 cases, whereas among acceptable mismatches, no inhibition was observed (in eight of eight), indicating the lack of specific antibodies. CONCLUSIONS: In highly sensitized patients, the introduction of soluble HLA-specific ELISAs is of additional and confirmatory value for the determination of acceptable mismatches. The major advantage of this approach is that antibody reactivity is tested against single antigens only.

Differential inhibitory effects of intravenous immunoglobulin preparations on HLA-alloantibodies in vitro.

BACKGROUND: Treatment of allosensitized patients with intravenously administered pooled immunoglobulin preparations (IVIG) may lead to a long-lasting reduction of anti-HLA alloantibody titers. An inhibitory response of IVIG preparations on lymphocytotoxicity is suggested to depend on IgG and to predict a successful reduction of anti-HLA alloantibodies upon the administration of high-dose IVIG in vivo. METHODS: In this study, we evaluated different IVIG preparations for their in vitro inhibitory capacity on lymphocytotoxicity and binding of anti-HLA alloantibodies to purified HLA antigens. For that purpose sera from 24 highly sensitized patients awaiting kidney transplantation and serological HLA testing reagents were used. Panel-reactive antibody (PRA) determinations using standard complement-dependent cytotoxicity testing and anti-HLA alloantibody determination by ELISA were carried out in the presence and absence of 50% (v/v) IVIG. RESULTS: The addition of IgG-containing IVIG preparations gave only a moderate inhibitory response judging from the average decrease of PRA levels (absolute DeltaPRA range: -2% to 16%), whereas the largest inhibition of lymphocytotoxicity was seen after the addition of IgM/IgA-containing IVIG preparations (absolute DeltaPRA range: 19% to 44%). For both IgG and IgM/IgA-containing IVIG preparations, the reduction of lymphocytotoxicity occurred in a dose-dependent fashion without a preference for particular anti-HLA class I antibody specificities. Significantly lower inhibitory effects on anti-HLA antibody reactivity were observed when the effects of IVIG preparations were monitored by ELISA (absolute DeltaPRA range: 7% to 22%). CONCLUSIONS: Our data suggest that the immunomodulatory capacity is largely caused by the IgM/IgA fraction of IVIG when analyzed by lymphocytotoxicity. The different effect on ELISA versus complement-dependent cytotoxicity testing suggests that interactions of IVIG with complement rather than anti-idiotypic antibodies may contribute to the inhibitory effects of IVIG in vitro.

Anti-HLA antibodies interfere in the detection of soluble HLA class I molecules.

Heart transplant rejection is routinely defined by histological evaluation of endomyocardial biopsies (EMB). As elevated levels of donor derived sHLA (dsHLA) can be detected in the serum of transplanted patients just before or during rejection, quantification of donor specific soluble counterparts of HLA Class I (sHLA-I) in the serum of the recipient may be a new way for non-invasive monitoring of graft rejection. However, not all patients show an increase of dsHLA at time of rejection. A reason for this might be that anti-donor-HLA antibodies, which are formed by the patient, form complexes with donor sHLA-I molecules. This masking or blocking of sHLA-I binding sites might cause false-negative results of tests detecting donor specific sHLA. Using HLA-antigen specific ELISA tests we could demonstrate that most anti-HLA antibodies block the detection of sHLA antigens in plasma, even in high dilutions of the antibody when the antibodies were not detectable in a CDC test. In general, HLA-antigen specific antibodies block the detection of sHLA molecules, while broadly-reactive antibodies, recognizing another epitope on the molecule, do not. The implication of these findings is that more than one dsHLA allotype within one patient should be tested to monitor graft rejection. In addition, sHLA monitoring must be combined with an HLA-antibody screening.

The application of human monoclonal antibodies for monitoring donor derived soluble HLA class I molecules in the serum of heart transplant recipients.

Increased levels of both donor and recipient derived HLA molecules can be found in serum and plasma of transplanted patients during rejection. Recent data suggest that levels of donor specific soluble HLA Class I (sHLA-1) correlate better with graft rejection than total sHLA Class I [1, 2]. Therefore, quantification of donor specific soluble counterparts of HLA Class I in the serum of the recipient may be a new way for non-invasive monitoring of rejection after organ transplantation. Up to now, only a limited number of mouse monoclonal antibodies (alpha HLA-A2, and alpha HLA-B7) has been used in enzyme linked immunosorbent assays (ELISAs) to detect donor specific HLA molecules in the plasma of transplant recipients. To monitor other donor-recipient combinations, we tested some of our HLA Class I specific human monoclonal antibodies, routinely used in complement dependent cytotoxicity, for their suitability in ELISA based assays. In the present model system, we used alpha HLA-A9 (BvK5C4) or alpha HLA-A3 (OK2F3) hybridoma-supernatant to set up a sHLA-A9 and sHLA-A3 specific ELISA. In a pilot study we show that these assays were sensitive enough to detect an increase of donor specific sHLA-I during rejection in the plasma of two heart transplant recipients. Use of a large set of human hybridoma's will enable monitoring most recipient/donor combinations in the near future.

Elevated serum HLA class I levels coincide with acute and chronic graft-versus-host disease.

The ability to predict the likely occurrence of graft-versus-host-disease (GVHD) after BMT would be extremely valuable. We performed a retrospective study on the correlation between soluble HLA class I (sHLA-I) levels and GVHD in the sera of 34 patients receiving an allogeneic BMT and in the sera of 12 patients receiving an autologous BMT. sHLA-I levels measured pre- and at different times post-BMT were correlated with the occurrence of post-BMT complications, ie acute graft-versus-host disease (aGVHD), chronic graft-versus-host disease (cGVHD), infections and relapse. No changes in sHLA-I levels (delta sHLA-I) occurred in autologous and allogeneic BMT patients without GVHD. In contrast, sHLA-I reached high levels in patients suffering from GVHD. Increased sHLA-I levels correlated strongly with episodes of both acute and chronic GVHD (P = 0.004 and P = 0.005, respectively). Also during relapse increased sHLA-I levels were found (P = 0.032). During infections sHLA-I levels increased, although not significantly. Kinetic studies gave no evidence that the increase in sHLA-I levels preceded the clinical occurrence of aGVHD or of cGVHD. A slight, but significant correlation was found between total blood bilirubin levels and sHLA-I levels in patients suffering from GVHD (P = 0.037), indicating the contribution of the liver as a source of sHLA-I. We conclude that measurements of sHLA-I levels do not function as a predictive parameter for GVHD, but can be valuable for the monitoring of GVHD after BMT.

Correlation between oral sex and a low incidence of preeclampsia: a role for soluble HLA in seminal fluid?

The involvement of immune mechanisms in the aetiology of preeclampsia is often suggested. Normal pregnancy is thought to be associated with a state of tolerance to the foreign antigens of the fetus, whereas in preeclamptic women this immunological tolerance might be hampered. The present study shows that oral sex and swallowing sperm is correlated with a diminished occurrence of preeclampsia which fits in the existing idea that a paternal factor is involved in the occurrence of preeclampsia. Because pregnancy has many similarities with transplantation, we hypothesize that induction of allogeneic tolerance to the paternal HLA molecules of the fetus may be crucial. Recent data suggest that exposure, and especially oral exposure to soluble HLA (sHLA) or HLA derived peptides can lead to transplantation tolerance. Similarly, sHLA antigens, that are present in the seminal plasma, might cause tolerance in the mother to paternal antigens. In order to test whether this indeed may be the case, we investigated whether sHLA antigens are present in seminal plasma. Using a specific ELISA we detected sHLA class I molecules in seminal plasma. The level varied between individuals and was related to the level in plasma. Further studies showed that these sHLA class I molecules included classical HLA class I alleles, such as sHLA-A2, -B7, -B51, -B35 and sHLA-A9. Preliminary data show lower levels of sHLA in seminal plasma in the preeclampsia group, although not significantly different from the control group. An extension of the present study is necessary to verify this hypothesis.

Donor-derived soluble HLA plasma levels can not be used to monitor graft rejection in heart transplant recipients.

OBJECTIVE: Increased levels of both donor- and recipient-derived HLA class I molecules (sHLA-I) can be found in serum or plasma of transplanted patients during rejection. Earlier data indicate that levels of donor-derived sHLA-I (dsHLA-I) correlate better with graft rejection than total sHLA Class I (Zavazava N, Kraatz E, Gassel AM, Muller-Ruchholtz W. Plasma MHC class I expression in cardiac graft patients: donor-specific soluble antigen in a pre-sensitized graft patient. Transplant Proc 1991;23:2258-2260; Claas FHJ, Jankowska-Gan E, DeVito LD, et al. Monitoring of heart transplant rejection using a donor-specific soluble HLA class I ELISA. Hum Immunol 1993;37:121). Therefore, quantifying donor-derived soluble counterparts of HLA Class I (sHLA-I) in the plasma of the recipient may offer a new possibility for non-invasive monitoring of rejection after organ transplantation. METHODS: In an extended study with 34 heart transplant recipients, we used sHLA-I specific ELISAs to monitor donor-derived soluble sHLA-A2, -A3, -A9, -B7, -B12 and B51. RESULTS: The assays were sensitive enough to detect dsHLA Class I in plasma of the recipients. However, the levels of sHLA were not found to be a useful tool for monitoring rejection. Rejection was often associated with low levels of donor sHLA. The recent finding that antibodies can inhibit the detection of sHLA molecules might explain this discrepancy. In order to test this hypothesis, patient sera were screened for the presence of anti-HLA antibodies and the results were related to the donor-derived sHLA levels. Only in four out of 34 patients HLA Class I specific antibodies could explain the low sHLA levels during rejection. CONCLUSIONS: In heart transplantation increased donor-derived sHLA levels are not a suitable marker for rejection and that antibody formation can not explain these results. Therefore, monitoring rejection episodes on the basis of donor-derived soluble HLA molecules is not a realistic approach to decrease the number of biopsies after heart transplantation.

Inhibition of gap junctional intercellular communication between primary human smooth muscle cells by tumor necrosis factor alpha.

Tumor necrosis factor alpha (TNF alpha), a pleiotrophic cytokine present in atherosclerotic lesions, caused a dose-dependent and persistent reduction in gap junctional intercellular communication (GJIC) between primary human smooth muscle cells in vitro. A continuous presence of TNF alpha was required for this persistent inhibition. Pretreatment of smooth muscle cells with ascorbic acid, alpha-tocopherol or glutathione prevented this inhibition of GJIC by TNF alpha. The persistent blockage of GJIC by continuous exposure to TNF alpha suggests that TNF alpha may share some mechanistic similarities with exogenous tumor promoters. Furthermore, this reduction in GJIC by TNF alpha may provide an additional link between the processes of atherosclerosis and carcinogenesis. The protection afforded by antioxidant compounds suggests a role for active oxygen species in the promotion stage of atherosclerosis.