[Neurovascular complications in fractures of the extremities, part 1 : Vascular lesions]. / Neurovaskuläre Komplikationen bei Frakturen der Extremitäten, Teil 1 : Gefäßläsionen.

Neurovascular injuries in fractures threaten at least the function of extremities. The timely interaction between diagnosis and treatment of vascular injuries helps to avoid a poor outcome or even fatal complications. An important parameter is to "think about it" for injuries under strain. An ankle-brachial index (ABI) of <0.9 is an indicator. Massive bleeding, manifest and long-lasting peripheral ischemia and a rapidly expanding hematoma necessitate an immediate surgical intervention. Endovascular techniques are recommended on the extremities of stable patients with circumscribed vascular lesions. The debate about the sequence of repair (vascular vs. osseous) has to be decided on an individual basis; however, when in doubt vascular repair should be given priority. Vessel reconstructions should be performed without tension and must be covered by vital soft tissues, the indications for fasciotomy should be liberally interpreted. The prognosis with respect to preservation of the extremity and long-term functional outcome substantially depends on the quality of treatment of accompanying injuries.

Feasibility of a multdisciplinary lung cancer videoconference between a peripheral hospital and a comprehensive cancer centre.

OBJECTIVE: Treatment of lung cancer patients is changing rapidly and new treatment options have emerged in recent years. In 2007, to guarantee the best treatment procedure for lung cancer patients being treated in our peripheral hospital, we decided to introduce an interdisciplinary tumour videoconference between the Haemato-Oncological Day Hospital in Merano and the Comprehensive Cancer Centre Innsbruck. This retrospective analysis aims to describe the feasibility of such a conference. PATIENTS AND METHODS: Two hundred and three patients with lung cancer treated at the peripheral hospital of Merano between May 2003 until May 2011 were retrospectively analysed. After introduction of the tumour videoconference in 2007, 54% (n = 110) of the patients in this cohort were discussed in the conference. RESULTS: One hundred and four videoconferences were performed. Videoconference was feasible for 110 patients. Radiotherapeutic treatments were prescribed more frequently in patients from the conference group. Overall, major and minor treatment changes were undertaken in 7% (n = 8) and 18% (n = 20), respectively. CONCLUSION: Interdisciplinary tumour videoconference is feasible between a peripheral hospital and a comprehensive cancer centre. Radiotherapeutic treatment was prescribed more frequently, suggesting that such a conference facilitates the access to cancer-centre-specific treatment modalities. Accordingly, tumour videoconference between a peripheral hospital and a cancer centre is to be recommend.

Timely course of SARS-CoV-2 infections and vaccinations in patients with hemato-oncological diseases: analysis of a real-life cohort.

BACKGROUND: The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has particularly impacted patients with hemato-oncological malignancies, as they showed not only a higher propensity for severe courses but also weaker immune responses after vaccination. Still, data on the influence of pandemic waves and vaccinations on outcomes are rare. This study aimed to analyze the timely course of infections and vaccinations in a real-life cohort of patients with hemato-oncological diseases. METHODS: In this cohort study, 1817 patients with hemato-oncological diseases from 1 February 2020 to 15 December 2022 at the 'Franz Tappeiner' Hospital in Merano/Meran, Italy, were followed for SARS-CoV-2 infections and vaccinations. RESULTS: Of 1817 patients with hemato-oncological malignancies, 735 (40.5%) were infected at least once with SARS-CoV-2, and 1614 (88.8%) received one or more doses of the approved vaccinations. Patients receiving antineoplastic treatment had a lower SARS-CoV-2 infection rate [35.1% versus 41.0%; odds ratio (OR) 0.78, 95% confidence interval (CI) 0.64-0.95], but higher risk of hospitalization (13.4% versus 6.9%; OR 2.11, 95% CI 1.25-3.69) compared with untreated patients. Overall, the case fatality rate (CFR) was 3.4%. Unvaccinated patients were more prone to severe coronavirus disease 2019 (COVID-19) courses requiring hospitalization (OR 2.34, 95% CI 1.25-4.36) and had a higher CFR (7.3% versus 1.6%; OR 4.98, 95% CI 2.16-12.98) than their vaccinated counterparts. In the Delta wave, patients with two vaccinations had a lower infection risk (OR 0.18, 95% CI 0.10-0.35) and tendentially lower hospitalization rates (OR 0.25, 95% CI 0.05-1.29) than unvaccinated patients. In the Omicron wave, 345/1198 (28.8%) patients with three or more vaccinations had breakthrough infections, resulting in a similar risk for infection (OR 0.88, 95% CI 0.60-1.30) but numerically lower risk for hospitalization (24/345, 7.0%) than unvaccinated individuals (4/40, 10.0%). Scheduled visits were postponed in 128/335 (38.2%) patients due to COVID-19, and deferrals correlated with pandemic wave (P = 0.002) and vaccination status (P < 0.001). CONCLUSIONS: SARS-CoV-2 infections and outcomes differ between distinct phases of the pandemic. Vaccination with variant-specific vaccines should be prioritized as general protective measures are increasingly lifted.

High expression of TROP2 correlates with poor prognosis in pancreatic cancer.

Pancreatic cancer is one of the most devastating human malignancies. Despite considerable research efforts, it remains resistant to almost all available treatment regimens. The human trophoblast cell-surface antigen, TROP2, was found to be strongly expressed in a variety of human epithelial cancers, correlating with aggressiveness and poor prognosis. TROP2 antigen expression was investigated retrospectively by immunohistochemistry in paraffin-embedded primary tumour tissue samples from a series (n=197) of consecutive patients with pancreatic adenocarcinoma. Survival was calculated using Kaplan-Meier curves. Parameters found to be of prognostic significance in univariate analysis were verified in a multivariate Cox regression model. TROP2 overexpression was observed in 109 (55%) of 197 pancreatic cancer patients and was significantly associated with decreased overall survival (P<0.01). By univariate analysis, TROP2 overexpression was found to correlate with the presence of lymph node metastasis (P=0.04) and tumour grade (P=0.01). Furthermore, in the subgroup of patients treated surgically with curative intent, TROP2 overexpression significantly correlated with poor progression-free survival (P<0.01). Multivariate analyses revealed TROP2 to be an independent prognosticator. These findings suggest for the first time that TROP2 could be a novel prognostic biomarker for pancreatic cancer. Targeting TROP2 might be a useful treatment approach for patients with pancreatic cancer overexpressing this cell-surface marker.

Importance of an 85 kDa membrane glycoprotein for a variety of cell-cell interactions.

The membrane molecule termed "7F7-antigen" has been found to be involved in several examples of cell-cell interactions. This 85 kDa glycoprotein with a protein core of about 55 kDa contains N-linked and O-linked carbohydrates. It has an isoelectric point of 8.0-8.5 and is expressed on 20% of peripheral blood mononuclear cells, 35% of peripheral blood B-cells, follicular dendritic cells and vascular endothelium. It is also expressed on activated T-cells and its expression on B-cells, fibroblasts and monocytes increases after treatment with PWM, interferon-gamma and after three days culture, respectively. The MAb 7F7 used to define this antigen inhibits the initiation of T-cell proliferation induced by anti-CD3, PHA, ConA and (weakly) allogenic stimulator cells, but does not affect the growth of IL-2 dependent T-cells and does not interfere with the killing of PHA-blasts by allogenic IL-2 dependent T-cells. 7F7 also inhibits the binding of C3-coated sheep erythrocytes to B-cells, the PMA-induced aggregation of U937 and the binding of activated T-cells to fibroblasts. The 7F7-antigen is expressed on some non-Hodgkin lymphomas of B-cell differentiation, particularly those with follicular structure, but not on Burkitt's lymphoma, ALL or carcinomas of various tissues. It is, however, found on fibrous tissue surrounding infiltrating carcinoma cells. The expression of a melanoma antigen, P3.58, which was shown to be identical to 7F7-antigen correlates with stage and spread of invasive melanoma. It was concluded that the 7F7-antigen, which is probably related to a previously described adherence molecule (ICAM-1), is of biological importance for the initiation of T-cell responses. With the possible exception of melanoma its expression on neoplastic cells in vivo is unlikely to be of importance for the spread of malignant disease.

A validated real-time quantitative PCR approach shows a correlation between tumor burden and successful ex vivo purging in follicular lymphoma patients.

OBJECTIVE: Purging procedures are increasingly used to provide stem cell collections devoid of contaminating tumor cells. In follicle center lymphoma (FCL), most approaches eradicate polymerase chain reaction (PCR);-detectable disease in only a fraction of harvests undergoing ex vivo manipulation. In this study we evaluated whether there is a relationship between tumor burden of stem cell harvests and successful clearance of PCR-detectable disease following ex vivo manipulation. MATERIALS AND METHODS: To address this issue, we developed a real-time PCR approach for quantitative measurement of tumor contamination using the bcl-2 rearrangement. Real-time PCR was used to evaluate the relationship between tumor burden of stem-cell harvests and purging effectiveness in PCR(+) samples derived from 10 FCL patients. Ex vivo purging was performed using the MaxSep cell separator (Baxter Immunotherapy, Deerfield, IL, USA). RESULTS: Our real-time PCR method proved effective, sensitive, accurate, and reproducible. Four collections were successfully cleared of minimal residual disease (MRD) whereas six remained PCR(+). Real-time PCR showed that the four collections successfully cleared of MRD had a prepurging tumor burden significantly lower than those remaining PCR(+) (p = 0.04). CONCLUSION: This study provides the first evidence that evaluation of tumor burden in stem-cell harvests by real-time PCR can predict the effectiveness of therapeutic intervention in non-Hodgkin's lymphoma. Based on these findings, we foresee a more widespread use of this technique to evaluate the impact of different therapeutic approaches in FCL.

Target value tailored (TVT) apheresis approach for blood progenitor cell collection after high-dose chemotherapy and rh-G-CSF.

Twenty-eight patients with different hematological diseases (17 non-Hodgkin's lymphoma, one Hodgkin's disease and 10 multiple myeloma) underwent peripheral blood progenitor cell (PBPC) collection after cyclophosphamide 7 g/m2 and rh-G-CSF. Fifty-eight leukaphereses were carried out with a fully automated PBPC collection procedure. Progenitor cell release was monitored by standardized determination of CD34+ cells in the peripheral blood. After a profound aplasia, a continuous increase in CD34+ cells in the peripheral blood was seen for at least 3-4 days. In 82% of our patients more than 2.5 x 10(6) CD34/kg could be collected using a standard apheresis of 10 l. There was a high correlation between the CD34+ cells in the peripheral blood and CD34+ cells/kg harvested. (r2 = 0.91). A relatively constant ratio (median 14.3, range 3.2-22.6) was found between CD34+ cells/kg and CFU-GM/kg. Based on the CD34 values of the pre-apheresis blood and the body weight of an individual patient and using the mathematical model of regression analysis (y = mx + b) for the correlation between the CD34+ cells/microliter in the pre-apheresis blood and the CD34+ cells/kg, it was possible to create a formula allowing for target value tailored apheresis. Using this formula, the blood volume which needs to be processed in order to harvest a desired number of CD34+ cells/kg can be calculated. This strategy can be applied to reduce the time for and the number of aphereses. Nineteen leukaphereses were carried out applying the formula. In 18 of 19 leukaphereses the expected CD34+/kg values were correctly achieved or exceeded. The formula was most reliable when the CD34 value was higher than 15/microliter and when the WBC count was below 20 x 10(9)/l in the pre-apheresis blood. For mobilizations using hematopoietic growth factors alone our formula is not applicable, because in most cases the pre-apheresis white blood cell count is higher than 20 x 10(9)/l and the collection efficacy of lymphomonocytoid cells decreases with a high pre-apheresis white blood cell count. The formula also works with other mobilization regimens that induce a pronounced aplasia.

Peripheral blood monoclonal B-cells predict the event free survival in multiple myeloma.

Reinfusion of myeloma progenitor cells may contribute to relapse of multiple myeloma after autologous stem cell transplantation. The aim of our study was to investigate whether monoclonal B-cells are present in the apheresis product and to evaluate the clinical relevance of these cells. Leukapheresis products of 55 patients were purged with anti-B-cell-Monoclonal antibodies (MoAbs) and immunobeads. Monoclonal B-cells were found in 85% of patients within the B-cell population. In one third of all myeloma patients, the majority of B-cells was represented by monoclonal myeloma progenitor B-cells, whereas in two thirds of patients monoclonal cells only represented a small part of the entire B-cell population. As shown by sequence analysis, monoclonal precursor B-cells and malignant plasma cells had the identical genetic CDR III sequence. The purging efficacy, using a negative selection system, was a median of 3 logs (range 1,5-3,5). No statistical difference in the purging efficacy was found when 3, 4 or 5 MoAbs against B-cells antigens were used. However, a tumor specific signal could be detected in the purged harvest of all patients, when the highly sensitive ASO-PCR approach was used. Furthermore, we found a direct correlation between the amount of remaining monoclonal cells after negative selection and the event free survival of myeloma patients. 10/15 patients with a median of 20 x 10(3) monoclonal cells in the purged product relapsed at a median of 1,4 years, whereas only 6/24 patients with an oligoclonal pattern including a low number of remaining monoclonal cells relapsed at a median of 2,2 years. The event free survival (EFS) was statistically different between the two groups (p = 0,014).

Low-dose thalidomide for multiple myeloma: interim analysis of a compassionate use program.

BACKGROUND: Despite recent advances in systemic and supportive therapies, multiple myeloma remains an incurable plasma cell malignancy. Novel therapeutic approaches are thus needed. Thalidomide has recently been recognized as an effective new agent for previously untreated, refractory or relapsed myeloma. PATIENTS AND METHODS: To evaluate the efficacy and tolerability of thalidomide in myeloma, we performed a retrospective analysis of 21 consecutive patients receiving thalidomide alone or in combination with dexamethasone and/or intermittent cyclophosphamide as first-line, maintenance or salvage therapy within a compassionate use program. RESULTS: Of the 21 patients, 16 (76.2%) had refractory or relapsed disease, including 7 (33.3%) patients relapsing after autologous stem cell transplantation. Three patients received thalidomide as maintenance therapy after having achieved a partial remission following autologous stem cell transplantation or conventional chemotherapy. Two patients were given thalidomide as first-line treatment for indolent disease. During long-term treatment (median 12 months, range 1-27 months), patients tolerated only low doses of thalidomide (50-150 mg/day) due to cumulative neurotoxicity. At a median follow-up of 16 months (range 1.5-28 months), we observed an overall response rate of 61.9% (50% for the subgroup receiving thalidomide alone; 77.8% for combination therapy) consisting of 1 complete response, 2 near-complete responses, 8 partial responses and 2 minor responses. Median progression-free survival was 20 months. CONCLUSIONS: We conclude that low-dose thalidomide (50-100 mg/day) alone or in combination is a safe, well-tolerated and effective form of therapy for patients with myeloma at various stages of disease.

The absence of SLP65 and Btk blocks B cell development at the preB cell receptor-positive stage.

Mice deficient for the adapter protein SLP65 (BLNK) show a partial block in early B cell development, reduced numbers of mature B cells in the periphery, an absence of B1 cells and a reduction of IgM and IgG3 serum immunoglobulin levels. A strikingly similar phenotype is observed in Btk-deficient mice. To investigate the consequences of mutations in both SLP65 and Btk, we generated SLP65/ Btk double-mutant mice by crossing the single-mutant mice. Analysis of the double-mutant mice reveals a much more severe defect in B cell development. B cells in the SLP65/Btk double-mutant mice are arrested at the preB cell stage and, surprisingly, express the preB cell receptor. Normally, preB cell receptor expression in wild-type mice is restricted to a very small fraction of B cells making it difficult to identify these cells in the bone marrow. Together, the data demonstrate the synergistic role of SLP65 and Btk in B cell development and describe a situation where large numbers of preB cell receptor-positive cells accumulate in the bone marrow and spleen.

Role of Epstein-Barr virus and soluble CD21 in persistent polyclonal B-cell lymphocytosis.

The expression of EBV proteins and immunological properties were studied in the first stable cell line (SM) established from a patient presenting with persistent polyclonal B-cell lymphocytosis (PPBL). SM cells which represent a small population of EBV-positive atypical cells found in the peripheral blood of the patient express the KI-1 antigen (CD30) as well as the proto-oncogene bcl-2 product and cell surface markers of mature activated B lymphocytes. The cells harbour an EBV subtype A genome and contain EBNA2 protein. This argues against a transformation-incompetent virus as the main cause of the chronic active EBV infection observed in our patient. Latent membrane protein (LMP1) was weakly expressed and found predominantly in a perinuclear localization, a location which could lead to decreased immunogenicity in vivo. Similar to the EBV-transformed marmoset cell line B95-8, SM cells were in part productively infected as transcription of the immediate early gene BZLF1 could be shown and in some cells high levels of EBV-genome were detected by in situ hybridization with a BamH1 W-probe. Comparable to the atypical cells in the peripheral blood of the patient. EBV small RNAs were not detected with EBER-specific probes. Of interest, we noticed a markedly increased production of soluble CD21 (sCD21) antigen by SM cells as compared to LCL-type Burkitt's lymphoma cell lines. This could explain the elevated sCD21 levels observed in the serum of our PPBL patient and confirms our previous findings in patients with acute EBV infection. It also suggests a possible role of sCD21 in EBV-mediated regulation of the immune response and provides a possible explanation for the dysregulation of the humoral immune system observed in PPBl patients.

Involvement in the initiation of T cell responses and structural features of an 85-kDa membrane activation antigen.

A monoclonal antibody, 7F7, directed at a recently described membrane activation antigen of 85 kDa was found to inhibit the T cell proliferation induced by an anti-CD3 antibody, phytohemagglutinin A and concanavalin A. The T cell response to allogenic stimulator cells was also weakly inhibited. The inhibition of these T cell responses was only obtained if the antibody was added within the first 8 h (first 24 h in the case of the concanavalin A response) of culture. In addition the antibody inhibited the formation of cellular aggregates seen in stimulated cultures when added within the first 8 h. The membrane glycoprotein recognized by 7F7 is shown to have a slightly different molecular mass on cells of different lineage, a protein core of 55 kDa and to contain 30-50% of N-linked as well as a small amount of O-linked carbohydrates and sialic acid residues. This study suggests that the highly glycosylated membrane activation antigen defined by antibody 7F7 could contribute to the contact between those cells which are involved in the initiation of T cell responses.

Epstein-Barr virus related hemophagocytic syndrome in a T-cell rich B-cell lymphoma.

We report the case of a 30-year-old woman who presented with an EBV related hemophagocytic syndrome. After a few months she developed a T-cell rich B-cell non-Hodgkin's lymphoma with liver involvement. Serological data demonstrated a reactivation of the EBV infection. Tumor progression with liver involvement occurred during treatment with conventional chemotherapy. Tumor reduction and disappearance of all masses was seen after starting high-dose sequential chemotherapy, followed by an autologous peripheral blood progenitor transplantation LMP-1 could be amplified in the tumor material by PCR technology, but no LMP-1 expression could be found in the few malignant B-cells with Reed-Sternberg morphology. Sequence analysis of the carboxy terminal of the LMP-1 region revealed the naturally occurring 30 bp deletion variant of the LMP-1 with multiple point mutations within the NF kb region. Since LMP-1 was not expressed in the malignant tumor cells, no evidence could be found, that EBV participated in the tumorigenesis of this case.

Simultaneous detection of FV Q506 and prothrombin 20210 A variation by allele-specific PCR.

BACKGROUND AND OBJECTIVE: Factor V Leiden is the most important risk factor for hereditary thromboembolism, whereas the mutation in the 3'-untranslated region of the prothrombin gene seems to be only a mild risk factor for thrombotic events. On the other hand the factor V mutation (Arg 506) is frequently coinherited with the prothrombin 3'-untranslated region G20210A variant and there is increasing evidence that the co-segregated prothrombin variant is an additional risk factor for venous thromboembolism, contributing to thrombotic manifestations. A rapid, simple and cost-effective screening method is, therefore, required for the detection of both factor V Leiden and the prothrombin variant A20210G. DESIGN AND METHODS: Eighty-eight patients were enrolled in this study. Forty-four had a previously identified factor V and/or prothrombin mutation, the remaining 44 patients served as negative controls. A multiplex allele specific oligonucleotide PCR was established for the simultaneous detection of the two genetic risk factors for thrombophilia. To test the specificity of the simultaneous ASO PCR approach, the mutated and physiological factor V and prothrombin amplification products were sequenced. RESULTS: The factor V Leiden mutation and the prothrombin variant were correctly identified in all of 44 patients with known mutations. Furthermore the test was able to detect the mutated factor V and the II variant alone, as well as in the cosegregated pattern. Five patients with a homozygous pattern of factor V Leiden or prothrombin variant were also correctly identified. The sensitivity of the test is therefore 100%. In none of the 44 control cases were false positive results seen. INTERPRETATION AND CONCLUSIONS: The ASO PCR test is a rapid, simple and cost-effective screening test for thrombophilia.

Abnormal development and function of B lymphocytes in mice deficient for the signaling adaptor protein SLP-65.

During signal transduction through the B cell antigen receptor (BCR), several signaling elements are brought together by the adaptor protein SLP-65. We have investigated the role of SLP-65 in B cell maturation and function in mice deficient for SLP-65. While the mice are viable, B cell development is affected at several stages. SLP-65-deficient mice show increased proportions of pre-B cells in the bone marrow and immature B cells in peripheral lymphoid organs. B1 B cells are lacking. The mice show lower IgM and IgG3 serum titers and poor IgM but normal IgG immune responses. Mutant B cells show reduced Ca2+ mobilization and reduced proliferative responses to B cell mitogens. We conclude that while playing an important role, SLP-65 is not always required for signaling from the BCR.

Transient myeloproliferative disorder with a CD7+ and CD56+ myeloid/natural killer cell precursor phenotype in a newborn.

Anewborn with a transient myeloproliferative disorder and a myeloid/natural killer cell leukemia phenotype is described. The blasts expressed CD7, CD33, CD34, CD56, and CD117 but did not react with cytoplasmic myeloperoxidase and were negative for cy CD22, HLA-DR, and CD90 expression. No megakaryoblastic surface markers were identified. The blast population disappeared from the peripheral blood and bone marrow within 2 months, but hepatomegaly and recurrent respiratory insufficiency persisted. The patient died of unilateral pneumonia in the third month of life. Neither extramedullary infiltration nor other hematologic signs of disease progression were found.

Determination of soluble CD21 as a parameter of B cell activation.

In this study we established a novel solid-phase immunoassay for CD21 using the time-resolved fluorescence of lanthanide chelates. The capture assay was able to detect concentrations of as low as 100 pg of CD21 antigen per millilitre of sample and was used for quantitative determination of CD21 in lysates of different cell lines as well as in patient serum specimens. CD21 was measured in lysates of tonsils and cell lines of B, T cell and myelomonocyte lineage, and appeared to consist of monomeric antigen under the detergent conditions used. Elevated levels of soluble CD21 were observed in serum of patients with Epstein-Barr virus (EBV) infection, a disease known to be associated with polyclonal B cell activation, and in infection with the lymphotropic rubella virus. Significantly increased levels were also found in malignancies which are associated with EBV. In patients with nasopharyngeal carcinoma (NPC), a correlation with the titre of EBV-specific IgA was observed, thus supporting a possible role of soluble CD21 as a marker for disease activity in certain malignancies. Our data suggest that measurement of soluble CD21 could serve as a marker for activation of the immune system and diseases involving the B cell lymphoid system. Possible mechanisms and functions of soluble CD21 are discussed.

Chronic active Epstein-Barr virus disease in a case of persistent polyclonal B-cell lymphocytosis.

Persistent polyclonal B-cell lymphocytosis (PPBL) is a rare haematological disorder. It is characterized by activated and morphologically atypical B lymphocytes and polyclonal IgM production and has been associated with female sex, cigarette smoking, and HLA-DR7 expression. We report a case of PPBL with intermitting symptoms compatible with a chronic fatigue syndrome, recurrent erythema nodosum and multiforme. Serological findings suggested a chronic active Epstein-Barr virus (EBV) infection. Messenger RNA of EBV immediate early gene transactivation BZLF1 was detected in peripheral blood lymphocytes by reverse transcriptase PCR indicating a persistent replication of the virus. Over 2 years of observation we detected varying numbers of atypical lymphocytes. These cells hybridized with a probe specific for the EBV internal repeat region (BamHI W) which indicates a productive infection. Of interest, no reaction was observed with a probe specific for the latency-associated small RNAs (EBERs). The immunological phenotype of the polyclonal B cells was similar to B-cell lines immortalized by EBV in vitro, expressing a number of activation molecules (CD23, CD25, CD54) and the bcl-2 protein. In summary, our findings suggest that persistent EBV replication might be crucial in the development of lymphoproliferative disorders such as PPBL.

Individual epitopes of an 85,000 MW membrane adherence molecule are variably expressed on cells of different lineage.

The recently reported 85,000 MW membrane activation antigen, provisionally termed 7F7 antigen, is involved in the initiation of T-cell responses, in the binding of C3b-coated sheep erythrocytes to B cells and in the phorbol ester-induced aggregation of U937, suggesting that it represents a membrane molecule important for cell-cell adherence. Three new monoclonal antibodies were raised against the purified antigen and used to examine the expression of individual epitopes on cells of different lineage. All antibodies reacted with the purified membrane antigen on Western blots. Antibodies 7G2 and 7C6 reacted only weakly with activated T cells, although the 85,000 MW 7F7 antigen is recognized on T cells by antibodies 7F7 and 8B9. Whereas 7F7 and 8B9 inhibit the phorbol ester-induced aggregation of U937 and the attachment of phytohaemagglutinin (PHA)-activated T cells to fibroblasts, antibody 7G2 was without inhibitory effect. Four antibodies raised against the P3.58 glycoprotein, a melanoma-associated antigen with biochemical features similar to the 7F7 antigen were shown to react with the purified 7F7 antigen on Western blots. These four antibodies also failed to react with activated T cells. In addition, 7F7 bound to a L cell transfectant prepared with human chromosomal DNA which expressed the P3.58 antigen. The results indicate that the 7F7 antigen and the P3.58 melanoma antigen are identical, that some epitopes of this adherence molecule are differentially expressed on individual cell types and that one epitope, which is only weakly expressed on activated T cells, does not contribute to the role of the 7F7 antigen in some examples of cell-cell adherence.