Combined utility of CD177, P53, CD105 and c-kit immunohistochemical stains improves the detection of myelodysplastic syndrome.

The diagnosis of myelodysplastic syndrome (MDS) relies primarily on identifying peripheral blood cytopenia and morphologic dysplasia as well as detecting cytogenetic aberrations in a subset of patients. Accumulating data points to the importance of examining certain immunophenotypic changes characteristic of MDS, most of which are tested by flow cytometry. The role of immunohistochemistry in the diagnostic workup of MDS is less known. In this study, we used immunohistochemistry to survey the expression patterns of CD177, P53, CD105 and c- kit in a cohort of MDS bone marrow specimens (n = 57) and compared the results with a control group of patients who had cytopenia for other benign conditions (n = 49). MDS cases showed significant higher rates of: CD177-loss (13/57, 23% vs 1/49, 2%; P = .0016), P53 overexpression (8/57, 14% vs none; P = .005) and the presence of clusters of CD105-positive cells (6/57, 11% vs none; P = .021). Increased c-kit-positive cells was more common in MDS patients, but not statistically significant (17/57, 30% vs 8/49, 16%; P = .102). On multivariate analysis, only loss of CD177 expression was significantly higher in MDS group (P = .014). These findings suggest that a panel of immunohistochemical stains could serve as an adjunct tool in investigating unexplained cytopenias and warrant further comparative studies with flow cytometry.

Human neutrophil antigen profiles in Banjar, Bugis, Champa, Jawa and Kelantan Malays in Peninsular Malaysia.

BACKGROUND: Human neutrophil antigens (HNA) are polymorphic and immunogenic proteins involved in the pathogenesis of neonatal alloimmune neutropenia, transfusion-related acute lung injury (TRALI) and transfusion-related alloimmune neutropenia. The characterisation of HNA at a population level is important for predicting the risk of alloimmunisation associated with blood transfusion and gestation and for anthropological studies. MATERIALS AND METHODS: Blood samples from 192 healthy, unrelated Malays were collected and genotyped using polymerase chain reaction-sequence specific primers (HNA-1, -3, -4) and polymerase chain reaction-restriction fragment length polymorphisms (HNA-5). The group comprised 30 Banjar, 37 Bugis, 51 Champa, 39 Jawa and 35 Kelantan Malays. RESULTS: The most common HNA alleles in the Malays studied were HNA-1a (0.641-0.765), -3a (0.676-0.867), -4a (0.943-1.000) and -5a (0.529-0.910). According to principal coordinate plots constructed using HNA allele frequencies, the Malay sub-ethnic groups are closely related and grouped together with other Asian populations. The risks of TRALI or neonatal neutropenia were not increased for subjects with HNA-1, -3 and -4 loci even for donor and recipient or pairs from different Malay sub-ethnic groups. Nonetheless, our estimates showed significantly higher risks of HNA alloimmunisation during pregnancy and transfusion between Malays and other genetically differentiated populations such as Africans and Europeans. DISCUSSION: This study reports HNA allele and genotype frequencies for the five Malay sub-ethnic groups living in Peninsular Malaysia for the first time. These Malay sub-ethnic groups show closer genetic relationships with other Asian populations than with Europeans and Africans. The distributions of HNA alleles in other lineages of people living in Malaysia (e.g. Chinese, Indian and Orang Asli) would be an interesting subject for future study.

Establishment of a global virtual laboratory for transplantation: a symposium report.

Advancing the field of transplantation by developing improved and novel treatment strategies will require a detailed understanding of changes and adaptations of alloimmunity, both over the short-term and long-term. Presently, we rely on traditional measures that may not optimally reflect benefits of new treatments. Thus, collecting reliable basic information about changes of the immune response along the entire posttransplantation course will improve our understanding of how immune mechanisms evolve and guide the introduction of novel clinical approaches. The gathering of good quality data from transplant recipients in various clinical trials will require immune monitoring that is reliable and comparable so that large sets of information from individual trials can be confidently analyzed to reach rigorous conclusions. A uniform standard of testing is thus a prerequisite toward this goal. Based on the assumption that the transplantation community will in general be supportive of this concept, this meeting proposed establishing a global virtual laboratory as a means of developing and disseminating detailed and rigorous protocols for the monitoring of alloimmune responses.

Paediatric essential thrombocythaemia: clinical and molecular features, diagnosis and treatment.

The incidence of essential thrombocythaemia (ET) in children (age ≤18 years) is extremely low. The natural course of the disorder in children has not been clarified. The rarity of patients and the variability of tested parameters make it difficult to draw any definitive conclusion in pathogenesis and diagnosis of paediatric ET. What makes the onset of thrombocytosis earlier in children is still uncertain. A diagnostic algorithm for paediatric ET has not been established, and current risk stratification used to guide therapeutic decisions in adults has not been validated in children. Vascular complications and transformation to myelofibrosis and leukaemia in this special entity have been reported, suggesting that ET in children is not an entirely benign disease. The crucial question is how to identify patients who are at high risk of complications and need treatment. There are insufficient data to recommend a specific agent in children. The purpose of this review is to outline the most recent progress in paediatric ET and to help with understanding the clinical course, molecular features, diagnosis and treatment strategies in this special group.

Gene expression analysis of a Helicobacter pylori-infected and high-salt diet-treated mouse gastric tumor model: identification of CD177 as a novel prognostic factor in patients with gastric cancer.

BACKGROUND: Helicobacter pylori (H. pylori) infection and excessive salt intake are known as important risk factors for stomach cancer in humans. However, interactions of these two factors with gene expression profiles during gastric carcinogenesis remain unclear. In the present study, we investigated the global gene expression associated with stomach carcinogenesis and prognosis of human gastric cancer using a mouse model. METHODS: To find candidate genes involved in stomach carcinogenesis, we firstly constructed a carcinogen-induced mouse gastric tumor model combined with H. pylori infection and high-salt diet. C57BL/6J mice were given N-methyl-N-nitrosourea in their drinking water and sacrificed after 40 weeks. Animals of a combination group were inoculated with H. pylori and fed a high-salt diet. Gene expression profiles in glandular stomach of the mice were investigated by oligonucleotide microarray. Second, we examined an availability of the candidate gene as prognostic factor for human patients. Immunohistochemical analysis of CD177, one of the up-regulated genes, was performed in human advanced gastric cancer specimens to evaluate the association with prognosis. RESULTS: The multiplicity of gastric tumor in carcinogen-treated mice was significantly increased by combination of H. pylori infection and high-salt diet. In the microarray analysis, 35 and 31 more than two-fold up-regulated and down-regulated genes, respectively, were detected in the H. pylori-infection and high-salt diet combined group compared with the other groups. Quantitative RT-PCR confirmed significant over-expression of two candidate genes including Cd177 and Reg3g. On immunohistochemical analysis of CD177 in human advanced gastric cancer specimens, over-expression was evident in 33 (60.0%) of 55 cases, significantly correlating with a favorable prognosis (P = 0.0294). Multivariate analysis including clinicopathological factors as covariates revealed high expression of CD177 to be an independent prognostic factor for overall survival. CONCLUSIONS: These results suggest that our mouse model combined with H. pylori infection and high-salt diet is useful for gene expression profiling in gastric carcinogenesis, providing evidence that CD177 is a novel prognostic factor for stomach cancer. This is the first report showing a prognostic correlation between CD177 expression and solid tumor behavior.

Identification of endothelial cell surface antigens encoded by genes other than HLA. A combined immunoprecipitation and proteomic approach for the identification of antigens recognized by antibodies against endothelial cells in transplant recipients.

It has been known for some time that transplant recipients may have antibodies to endothelial cells which are not detected on lymphocytes. However, little progress has been made in the analysis of these endothelial antigens. In the present experiments we have attempted to characterize endothelial cell surface antigens to which antibodies were produced during graft rejection. We have used a panel of endothelial cells from umbilical cord veins and found that antibodies with a polymorphic pattern in the panel appeared to correlate with transplant failure of kidney allografts and with the development of transplant-related coronary artery disease (TCAD) in heart transplant recipients. Among 39 patients with kidney allografts, 21 were negative for antibodies to endothelial cells and did well and 18 were positive and had frequent transplant loss (p=0.001). In 18 patients with TCAD and 20 patients of a comparator group without TCAD, association of coronary disease with endothelial cell antibodies was observed (p<0.02). To characterize the endothelial antigens responsible for these serologic reactions we performed immunoprecipitation of reactive antibodies with the corresponding endothelial cell surface antigens, followed by protein identification of the target antigens. Nine proteins were identified in these experiments, 5 were non-polymorphic and appeared to represent autoantigens. Four of the isolated proteins appeared to be polymorphic. They were the Human Major Histocompatibility Complex class I chain-related gene A (MICA), already known to be associated with antibody production and graft failure, human keratin 1, a protein known to be polymorphic and expressed on the surface of endothelial cells, eukaryotic translation initiation factor (EIF) 2A and ErbB3-binding protein 1. The possible role of keratin 1 and the other antigens in allograft rejection requires further investigation.

Rapid enzyme-linked immunosorbent assay for the detection of antibodies against human neutrophil antigens -1a, -1b, and -1c.

BACKGROUND: Several methods exist for the detection of neutrophil antibodies; most of them, however, require fresh neutrophils. In this study, an enzyme-linked immunosorbent assay (ELISA) using recombinant HNA-1 antigens (rHNAs) was developed to detect HNA-1a, -1b, and -1c alloantibodies in serum samples. STUDY DESIGN AND METHODS: Soluble rHNA-1a, -1b, and -1c were isolated from culture supernatant of transfected insect cells. Purified rHNA antigens were immobilized on microtiter wells using antibody against V5-Tag protein. Sera were added, and bound antibodies were detected by enzyme-labeled secondary antibodies. In parallel, monoclonal antibody-immobilized granulocyte antigen (MAIGA) was performed with two different monoclonal antibodies (MoAbs) against FcγRIIIb (3G8 and BW209). RESULTS: Fifteen MAIGA-positive sera containing HNA-1a alloantibodies were tested in ELISA. Thirteen of 15 (86.7%) MAIGA-positive sera captured by MoAbs 3G8 and/or BW209 reacted specifically with rHNA-1a. Four (26.7%) HNA-1a sera showed additional reaction with rHNA-1c. When anti-HNA-1b alloantibodies were analyzed in ELISA, 13 of 15 (86.7%) showed specific positive reaction with rHNA-1b, and 12 of 15 (80.0%) cross-reacted with rHNA-1c. Two HNA-1c sera reacted specifically with rHNA-1c. Immunoprecipitation analysis of all ELISA-negative HNA-1a and -1b sera did not show any specific band indicating false-positive reaction of these sera in MAIGA assay. CONCLUSIONS: These results suggested that rapid ELISA using recombinant neutrophil antigens may provide a valuable method for rapid screening of human alloantibodies against HNA-1a, -1b, and -1c in patients with neutropenia and in blood donors.

Red cells from the original JAL+ proband are also DAK+ and STEM+.

BACKGROUND: The low-prevalence Rh antigen, JAL, was named after the index case, Mr. J. Allen. Based on reactivity of seven multi-specific sera with his RBCs, it was apparent that they express at least one additional low-prevalence antigen. The purpose of this study was to investigate the other low-prevalence antigen(s) on J. Allen's RBCs. METHODS: Blood samples and reagents were from our collections. Hemagglutination and DNA analyses were performed by standard methods. RESULTS: Our DNA analyses confirmed the presence of RHCE*ceS(340T) in J. Allen and revealed the presence of RHCE*ceBI (ce 48C, 712G, 818T, 1132G) and RHD*DOL (509T, 667T). RBCs from J. Allen were agglutinated by anti-JAL, anti-STEM, and anti-DAK. Two of the reactive multi-specific sera reported in the original paper reacted with RBCs from J. Allen, and with RBCs from four other people with RHCE*ceBI, including the original STEM+ index case (P. Stemper) but not with RBCs with the DIIIa, DAK+ phenotype. We conclude that they contain anti-STEM. CONCLUSION: J.Allen's RBCs express the low-prevalence Rh antigens, JAL, V/VS (extremely weakly), STEM, and DAK. The presence of JAL on the variant Rhce, RhceJAL (16Cys, 114Trp, 245Val), STEM on the variant Rhce, RhceBI (16Cys, 238Val, 273Val, 378Val), and DAK on the variant RhD (170Thr, 223Val), encoded by RHD*DOL in trans to RHCE*ceBI is consistent with expression of these antigens. When J. Allen RBCs are used to detect and identify an anti-JAL, it is important to remember that they also express STEM and DAK.

Granulocyte antibody screening: evaluation of a bead-based assay in comparison with classical methods.

BACKGROUND: Granulocyte antibodies have been implicated in allo- and autoimmune neutropenia and in transfusion reactions. STUDY DESIGN AND METHODS: Fifty-one sera from suspected alloimmune neutropenia or transfusion-related acute lung injury (TRALI) and 40 sera from suspected autoimmune neutropenia were tested for granulocyte antibodies using LABScreen MULTI (One Lambda, Inc.), compared with classical tests (flow cytometry [FC] and granulocyte agglutination [GAT] followed by monoclonal antibody-specific immobilization of granulocyte antigens [MAIGA]). RESULTS: In alloimmune situations, 48 sera were concordant (94%), two sera positive for HNA with LABScreen MULTI were negative by FC/GAT and/or MAIGA, and one serum sample negative for HNA with LABScreen MULTI was positive by classical tests. In autoimmune neutropenia, 30 sera were concordant (75%), four sera positive for HNA with LABScreen MULTI were negative by FC/GAT and/or MAIGA, and six sera negative for HNA with LABScreen MULTI were positive by FC/GAT and/or MAIGA. For detection of autoantibodies, the LABScreen MULTI was less concordant. However, with the exception of one case, the discrepancies were observed in sera that did not show a clear specificity. CONCLUSIONS: LABScreen MULTI correlated well with our classical methods for HNA-1 and HNA-2a antibody screening. It can be used for screening blood donors or patients suspected of TRALI, but GAT is still needed for HNA-3a antibody screening.

Human neutrophil alloantigen-1a, -1b, -2, -3a and -4a frequencies in Brazilians.

Human neutrophil reactive antibodies may cause clinical disorders such as transfusion-related acute lung injury, febrile transfusion reactions, alloimmune neonatal neutropenia, immune neutropenia after stem cell transplantation, refractoriness to granulocyte transfusion, drug-induced neutropenia and autoimmune neutropenia. Using the granulocyte immunofluorescence test by flow cytometry, the phenotypic frequencies of the human neutrophil alloantigens (HNA)-1a, -1b, -2, -3a and -4a were determined in 100 healthy Brazilian persons. Neutrophils were separated from blood samples by sedimentation, centrifugated and incubated with HNA-specific alloantibody plus fluorescein isothiocyanate-labeled F(ab')(2) fragments of anti-human IgG. The results showed that the phenotype frequencies of HNA-1a, -1b, -2a, -3a and -4a were 65%, 83%, 97%, 95% and 94%, respectively. We detected that neutrophils from 17% of Brazilians typed positive only with anti-HNA-1a (HNA-1a/a), 35% only with anti-HNA-1b (HNA-1b/b) and 48% reacted with both antibodies (HNA-1a/b). The frequencies found for HNA-1a and -1b were quite similar to that reported among Africans and American-Africans, but different from those found in Japanese and Chinese. In addition, our data showed that the frequencies of HNA-2, -3a and -4a in Brazilians were comparable with those observed in Caucasians. The determination of HNAs frequencies among populations with distinct racial backgrounds is important not only for anthropological reasons, but also for neonatal typing in suspected cases of alloimmune neutropenia or when patients are severely neutropenic.

Allospecific CD154+ T cells identify rejection-prone recipients after pediatric small-bowel transplantation.

BACKGROUND: Up to 70% of children with small bowel transplantation (SBTx) experience acute cellular rejection (ACR). Allospecific CD154+ T cells predict liver ACR in children in a novel, 16-hour mixed leukocyte response (MLR) assay, but remain untested in SBTx. METHODS: The expression of CD154 was measured in 4 subsets-naive (N) and memory (M) CD154+ T-helper (Th) and T-cytotoxic (Tc) cells (ie, CD154+ ThN, CD154+ ThM, CD154+ TcN, and CD154+ TcM, respectively)-in the MLR of single blood samples obtained from 32 children with SBTx within 60 days of SBTx biopsy. Children showing ACR in these biopsies were termed Rejectors. The ratio of donor-induced to third-party-induced CD154+ T cells was called the immunoreactivity index (IR). We hypothesized that IR >1 denoted increased donor-specific alloreactivity and increased risk of rejection; in contrast, IR <1 implied decreased risk. CD154 expression was correlated with the expression of CTLA4, a negative T-cell costimulator that antagonizes and is inversely related to CD154 (n = 18). RESULTS: Rejectors showed significantly greater numbers of donor-specific CD154+ T-cell subsets. Logistic regression analysis and leave-one-out cross validation followed by receiver operating characteristic analysis showed that, among the 4 subsets, IR > or =1.23 for CD154+ TcM identified Rejectors with a sensitivity and specificity of 93% and 88%. Also, a significant negative correlation was observed between CD154 expression and CTLA4 expression in allospecific Tc (Spearman's rho = -0.616, P = .006) but not in Th. CONCLUSION: Allospecific CD154+ TcM identify rejection-prone children with SBTx.

Allergic airway hyperreactivity increases the risk for corneal allograft rejection.

Corneal allografts transplanted into hosts with allergic conjunctivitis experience an increased incidence and swifter tempo of immune rejection compared to corneal allografts transplanted to nonallergic hosts. Previous findings suggested that increased risk for rejection was not a local effect produced by an inflamed eye, but was due to perturbation of the systemic immune responses to alloantigens on the corneal allograft. We tested the hypothesis that another allergic disease, airway hyperreactivity (AHR), would also increase the risk for corneal allograft rejection. Induction of AHR with either ovalbumin (OVA) or short ragweed (SRW) extract prior to keratoplasty resulted in a steep increase in the speed and incidence of corneal allograft rejection. Delayed-type hypersensitivity (DTH) responses to corneal alloantigens were closely associated with corneal allograft rejection. However, the deleterious effect of AHR on corneal allograft survival was not reflected in a heightened magnitude of allospecific DTH, cytotoxic T lymphocyte and lymphoproliferative responses to the alloantigens on the corneal allograft. Unlike Th2-based immediate hypersensitivity, CD8+ T-cell-based contact hypersensitivity to oxazolone did not increase the risk for corneal allograft rejection. Thus, Th2-based allergic diseases significantly reduce the immune privilege of the corneal allograft and represent important risk factors for consideration in the atopic patient.

Coexpression of CD177 and membrane proteinase 3 on neutrophils in antineutrophil cytoplasmic autoantibody-associated systemic vasculitis: anti-proteinase 3-mediated neutrophil activation is independent of the role of CD177-expressing neutrophils.

OBJECTIVE: Wegener's granulomatosis (WG) is strongly associated with antineutrophil cytoplasmic autoantibodies (ANCAs) directed against proteinase 3 (PR3). Recent studies have shown that membrane-bound PR3 (mPR3) is differentially expressed and colocalizes with CD177/NB1 on circulating neutrophils. We undertook this study to assess the differential expression of CD177 on neutrophils from patients with ANCA-associated systemic vasculitis (ASV) in comparison with patients with systemic lupus erythematosus (SLE), patients with rheumatoid arthritis (RA), and healthy individuals, and to investigate whether colocalization of mPR3 and CD177 affects anti-PR3-mediated neutrophil activation. METHODS: Expression of CD177 and mPR3 was analyzed by flow cytometry on isolated neutrophils from patients with ASV (n=53), those with SLE (n=30), those with RA (n=26), and healthy controls (n=31). Neutrophil activation mediated by anti-PR3 antibodies was assessed by measuring the oxidative burst with a dihydrorhodamine assay. RESULTS: Percentages of CD177-expressing neutrophils were significantly higher in patients with ASV and those with SLE than in healthy controls. In 3 healthy donors, CD177 expression was not detected. After priming with tumor necrosis factor alpha, neutrophils remained negative for CD177 while mPR3 expression was induced. Neutrophils from CD177-negative donors or CD177- neutrophils sorted from donors with bimodal expression were susceptible to anti-PR3-mediated oxidative burst. Variation in the extent of anti-PR3-mediated neutrophil activation among different donors occurred independent of the percentage of CD177-expressing neutrophils. CONCLUSION: Membrane expression of CD177 on circulating neutrophils is increased in patients with ASV and in those with SLE, but not in RA patients. However, primed neutrophils from CD177-negative individuals also express mPR3 and are susceptible to anti-PR3-mediated oxidative burst, suggesting that recruitment of CD177-independent mPR3 is involved in anti-PR3-induced neutrophil activation.

Identification of the avian B-cell-specific Bu-1 alloantigen by a novel monoclonal antibody.

A panel of monoclonal antibodies was generated against the guinea fowl's bursal cells. One of the antibodies, designated BoA1, recognized both cortical and medullary B cells of bursal follicles and B cell dependent regions of peripheral lymphoid organs, like germinal centers and splenic periellipsoidal regions. The staining pattern of this monoclonal antibody is similar to other antibodies (L22, 11G2, AV20), which also identify the Bu-1 antigens. Under reducing conditions, the molecular weight of the BoA1 antigen is 70 to 73 kDa, and after immunoprecipitation it proved to be identical with the antigen recognized by the AV20 antibody. It is unique for this novel monoclonal antibody that it shows wide range cross-reactivity with different avian species, like chicken, quail, guinea fowl, and turkey. Therefore, this Bu-1-specific monoclonal antibody could be a versatile tool for studying the B cell development in different domesticated birds.

Human sperm protein encyclopedia and alloantigen index: mining novel allo-antigens using sera from ASA-positive infertile patients and vasectomized men.

Anti-sperm antibodies (ASA) are an important cause of immunological infertility. The objective of this study was to identify immunodominant sperm antigens recognized by anti-sperm antibodies (ASA) in serum samples of infertile men, women and vasectomized men. High-resolution two-dimensional gel electrophoresis was employed to separate human sperm proteins using isoelectric focusing (IEF) or nonequilibrium pH gradient electrophoresis (NEPHGE), followed by PAGE and Western blotting. Serum samples from five infertile male and five infertile female subjects that contained ASA as assayed by the immunobead binding test (IBT), were analyzed by Western blotting using NEPHGE gels followed by enhanced chemiluminescence (ECL) to identify the basic sperm antigens reactive to the sera. Serum samples from five fertile male and five fertile female subjects that were ASA-negative by IBT were used as controls. Serum samples from six vasectomized men collected before vasectomy and at different time intervals until 6 months after vasectomy were analyzed by Western blotting using IEF gels. The ECL blots were analyzed to compare immunoreactivity between serum samples from fertile and infertile subjects and identify antigens unique to sera of the infertile subjects. Similarly, immunoreactivity between serum samples from pre- and post-vasectomy was compared to identify antigens unique to sera collected following vasectomy. Five allo-antigenic basic protein spots were recognized by sera from infertile males but not from fertile subjects. Five sperm iso-antigenic basic spots were recognized by infertile female subjects. Two among six of the vasectomized men's sera showed a difference in the Western blot profile 6 months after vasectomy, recognizing at least one new protein spot in each case when compared to pre-vasectomy sera. The acrosomal protein SP-10 was identified as an alloantigen recognized by a post-vasectomy serum. Molecular identities of the known allo- and iso-antigens identified in this study and in previous studies from this laboratory are reviewed and discussed.

Monitoring neutrophil engraftment in allogeneic stem cell transplantation by flow cytometric analysis of neutrophil-specific antigens NA1 and NA2.

Neutrophil-specific antigen (NA) expression on neutrophils was analysed in 18 Japanese children before and after allogeneic stem cell transplantation (allo-SCT) with myeloablative regimen. Donor-recipient NA-incompatibility was present in one of eight NA1/NA2 heterozygous patients and eight of 10 NA1/NA1 or NA2/NA2 homozygous patients. After allo-SCTs from NA-incompatible donors, a neutrophil recipient-to-donor conversion was confirmed in all cases. Conversion to donor NA type was complete before the absolute neutrophil count reached 0.1 x 10(9)/l. These observations indicate that flow cytometric analysis of NA antigens is a simple and useful method for monitoring neutrophil engraftment in NA-incompatible allo-SCT.

In vivo study of T-cell responses to skin alloantigens in Xenopus using a novel whole-mount immunohistology method.

BACKGROUND: The African clawed frog, Xenopus, is a widely used comparative model for studying the immune response to transplantation antigens. METHODS: To better define the effector cells involved in the immune response to skin alloantigens of the frog Xenopus laevis, we have adapted a whole-mount immunohistology procedure used in mice that enables us to visualize leukocyte infiltration into unfixed transplanted skin tissues using fluorescent antibodies. We characterized the leukocyte populations present in donor skin at different times after transplantation using anti-class II and CD8 monoclonal antibodies. RESULTS: In autografts, only class II Langerhans or dendritic-like cells and very few CD8 T cells were detected. In contrast, major histocompatibility complex (MHC) disparate skin grafts at the peak of acute rejection (seven days posttransplantation, 50% rejection of pigment cells) were infiltrated with a large number of bright class II leukocytes, the majority of which were CD8 T cells. Most of these cells were located outside blood vessels and often near areas lacking pigmentation. Compared to MHC-disparate skin grafts, skin differing from the host only by minor histocompatibility antigens undergoes slower (i.e., chronic) rejection; interestingly, however, it was infiltrated by similar numbers of class II and CD8 T cell effectors, but with delayed kinetics (i.e., peaked around 15 days posttransplantation). CONCLUSIONS: Our data provide direct in vivo evidence of marked infiltration of effector leukocytes, a majority of which are CD8 T cells that occurs at the onset of tissue destruction of skin allografts.

Presence of D8/17 B-cell marker in patients with poststreptococcal reactive arthritis.

An elevated expression of the alloantigen D8/17 on B lymphocytes has been previously proposed as a susceptibility marker in rheumatic fever. The aim of the study was to investigate the presence of the D8/17 marker on B lymphocytes in poststreptococcal reactive arthritis (PSRA). The study sample included 19 patients (15 boys, 4 girls; mean age 11.7 +/- 5.4 years) who were diagnosed with PSRA (mean age at diagnosis, 9.4 +/- 5.6 years) and 18 healthy controls (10 boys and 8 girls) matched for ethnic background. B-cell D8/17 expression was tested by flow cytometry assay using monoclonal antibodies. Laboratory results showed a higher expression of D8/17 in the patient group (23.1 +/- 10.4%, range 11.6-51.9%) than in the control group (17.1 +/- 8.2%, range 7.1-35.7) in controls; this difference was statistically significant after log transformation of the data (P = 0.035). The high rate of expression of the D8/17 marker in patients with PSRA suggests that RF and PSRA share the same genetic susceptibility.