T-cell Differentiation Antigens Research Articles

Hiroshi Shiku, MD, PhD: In Memoriam (1943–2022)

Hiroshi Shiku, MD, PhD: In Memoriam (1943–2022)

PO-515 Transcriptome analysis identified alcam expression as potential biomarker to LSCC patient’s outcome

IntroductionLaryngeal squamous cell carcinoma (LSCC) is one of the most incidence tumours in the world, especially in developing countries, such as Brazil. The main risk factors for LSCC are tobacco and alcohol consumption and it usually occurs in patients older than 60 years. Similarly to other head and neck tumours, LSCC is a major health problem because of poor prognosis and slight improvement in the five-year survival during the past four decades. Therefore, our objective was to better understand the LSCC transcriptome, identifying possible prognosis biomarkers and novel therapy targets.Material and methodsWas carried out a gene expression profile analysis using the Human Exon 1.0 ST microarray chip. To this end, the expression profile of 14 tumour tissues were compared with 12­matched non­malignant mucosa.Results and discussionTranscriptome analysis pointed out 817 differentially expressed genes (DEG), 315 of which with overexpression in tumour and 502 underexpressed when compared with matched non­malignant mucosa. Performing a survival analysis across all overexpressed DEG, 24 genes were related to patients survival (ACOX1, ACVR1, ADH7, AGFG2, ALCAM, BTBD11, C12orf75, CDK14, CYP2C19, GBP6, GLTO, GNG4, LOX, LYPD6B, ME1, NPEPPS, ODC1, PMM1, PTGR1, SERPINA3, ST3GAL4, TDP52L1, ZDHHC13 and ZNF750). The prognostic values of these 24 genes were, then, validated in an independent LSCC data set of The Cancer Genome Atlas (TCGA) and the expression data, patient’s clinic and pathological features were analysed in Log-rank Test. Perineural invasion, commitment of surgical margins and expression of LOX, ALCAM, BTBD11 and LYPD68 showed p<0.05 and were selected to multivariate analysis applying Cox regression model. After age and tumour stage-adjustment, perineural invasion, commitment of surgical margins and ALCAM expression were classified as independent prognostic factors to LSCC patients. LSCC-patients displaying ALCAM high expression presented 4.5-fold increased death risk. ALCAM gene encodes the activated leukocyte cell adhesion molecule protein, also known as CD166, which is a member of a subfamily of immunoglobulin receptors. This protein binds to T-cell differentiation antigen CD6, and is implicated in the processes of cell adhesion and migration.ConclusionALCAM expression might be an independent prognosis biomarker to LSCC patients. Furthermore, in vitro, in vivo and pre-clinical analyses must be performed to reinforce this hypothesis.

T-cell/myeloid mixed-phenotype acute leukemia with monocytic differentiation and isolated 17p deletion.

Mixed phenotype acute leukemia is a rare subtype of leukemia that probably arises from a hematopoietic pluripotent stem cell. The co-expression of two of myeloid, B- or T-lymphoid antigens is the hallmark of this disease. Herein, the case of a 28-year-old female patient is reported who presented with hemoglobin of 5.8 g/dL, white blood cell count of 138 × 109/L and platelet count of 12 × 109/L. The differential count of peripheral blood revealed 96% of blasts. Moreover, the patient presented with lymphadenopathy, splenomegaly and bone marrow infiltration by monocytoid blasts characterized as 7% positivity by Sudan Black cytochemical staining. Immunophenotyping revealed the involvement of blasts of both T- and monocytic lineages. The cytogenetic analysis showed an isolated 17p deletion. Thus, the diagnosis of T-cell/myeloid mixed phenotype acute leukemia was made with two particular rare features, that is, the monocytic differentiation and the 17p deletion as unique cytogenetic abnormalities. The possibility of concomitant expressions of T-cell and monocytic differentiation antigens in the same blast population is hard to explain using the classical model of hematopoiesis. However, recent studies have suggested that myeloid potential persists even when the lineage branches segregate toward B- and T-cells. The role of an isolated 17p deletion in the pathogenesis of this condition is unclear. At present, the patient is in complete remission after an allogeneic stem cell transplantation procedure.

Expression of Master Regulators of Helper T-Cell Differentiation in Peripheral T-Cell Lymphoma, Not Otherwise Specified by Immunohistochemical Analysis.

Abstract 5004 BackgroundPeripheral T-cell lymphoma, not otherwise specified (PTCL-NOS) comprises nodal and extranodal mature T-cell lymphomas, which do not correspond to any of the specifically defined entities of mature T-cell lymphoma in the current classification.During T-cell maturation, naïve T-cells include two distinct cell types, CD4-positive helper T-cells (Th) and CD8-positive cytotoxic T-cells. Following antigen stimulation, naïve Th cells differentiate into several subtypes of effector Th cells, including helper T-cells type1 (Th1), helper T-cells type 2 (Th2), follicular helper T-cells (TFH), regulatory T-cells (Treg), IL-17 producing T-cells (Th17), central memory T-cells (TCM), and effector memory T-cells (TEM).Previously, these subtypes of effector Th cells have been classified according to their pattern of cytokine secretion and expression of surface antigens, including chemokine receptors. More recent immunological researches have identified several transcription factors responsible for T-cell differentiation. The master regulators associated with Th, Th1, Th2, Th17, and Treg differentiation are reported to be Th-POK, T-Bet, GATA3, RORγt, and FOXP3, respectively.The origin of the neoplastic cells of PTCL-NOS is thought to be effector Th cells because the tumor cells usually express specific surface antigens such as pan-T-cell markers (CD2 and CD3), an effector T-cell marker (CD45RO), and a Th marker (CD4). However, the normal cellular derivation of PTCL-NOS remains unclear because the immunophenotypic profiles of PTCL-NOS are heterogeneous and not entirely disease specific.To presume the normal counterparts of PTCL-NOS, we used immunohistochemical analysis to examine the expression of the master regulators of T-cell differentiation and surface antigens, including chemokine receptors associated with the subtypes of Th cells. Patients and MethodsThe study population included ten Japanese patients who were diagnosed histopathologically with PTCL-NOS at the hospital of Kyoto Prefectural University of Medicine from 1993 to 2008. There were six male and four female patients who ranged in age from 26 to 78 years (mean 56 years) at diagnosis.Immunohistochemical staining was applied to 4-μm-thick paraffin-embedded sections of diagnostic lymph node, skin or liver tumor biopsy specimens. Sections were stained using a standard indirect avidin-biotin horseradish peroxidase method and diaminobenzidine (DAB) color development. Cases were considered positive if 25% or more of the tumor cells were stained with an antibody. For negative and positive staining controls, we used paraffin-embedded tissue sections of tonsillitis, nonspecific lymphadenitis, AILT, follicular lymphoma and diffuse large B-cell lymphoma. ResultsFirst, we examined the expression of the master regulator of helper T-cells (Th-POK) and the marker of effector T-cells (CD45RO), and all cases were positive for both.Next, we examined the expression of the master regulators of differentiation to subpopulations within Th cells (Th1, Th2, Treg and Th17). Three cases each were positive for T-Bet, and GATA3, but none of the cases showed FOXP3 or RORγt.Among the four cases not expressing these master regulators, two cases were positive for the surface antigens of central memory (TCM) (CCR7 and CD62L), and one case was positive for follicular helper T-cell (TFH) phenotype (BCL6, CXCL13 and PD-1). The remaining case was negative for all markers of effector Th subtypes. ConclusionsAll ten PTCL-NOS cases exhibited CD45RO and Th-POK, which characterized effector helper T-cells. Furthermore, the lymphoma cells of nine of the ten cases exhibited the expression of master regulators or surface antigens which characterized Th1, Th2, TCM and TFH. DisclosuresNo relevant conflicts of interest to declare.

Expression of the T-cell differentiation antigen RT6.2 in T-cell lines is correlated with hypomethylation of the RT6 promoter

Expression of the T-cell differentiation antigen RT6.2 in T-cell lines is correlated with hypomethylation of the RT6 promoter

Perturbation of beta1-integrin function alters the development of murine mammary gland.

The expression of a transgene coding for a chimeric molecule, containing the cytoplasmic and transmembrane domains of the beta1-integrin chain and the extracellular domain of the T-cell differentiation antigen CD4, was targeted to the mouse mammary gland by the mouse mammary tumor virus (MMTV) promoter. The chimera does not interact with the extracellular ligands; however, its expression in cultured cells was shown to interfere with focal adhesion kinase (FAK) phosphorylation following ligation of endogenous beta1-integrin. Therefore, expression of the transgenic protein on the cell surface should uncouple adhesion from intracellular events associated with the beta1-cytoplasmic domain and thus perturb beta1-integrin functions. Although most of the transgenic females were able to lactate, their mammary glands had a phenotype clearly distinct from that of wild-type mice. At mid-pregnancy and the beginning of lactation, transgenic glands were underdeveloped and the epithelial cell proliferation rates were decreased, while the apoptosis levels were higher than in wild-type glands. In lactation, the amounts of the whey acidic protein (WAP) and beta-casein gene transcripts were diminished, and the basement membrane component, laminin and the beta4-integrin chain accumulated at the lateral surface of luminal epithelial cells, revealing defects in polarization. Our observations prove that in vivo, beta1-integrins are involved in control of proliferation, apoptosis, differentiation and maintenance of baso-apical polarity of mammary epithelial cells, and therefore are essential for normal mammary gland development and function.

Modulation of WC1, a lineage-specific cell surface molecule of gamma/delta T cells augments cellular proliferation.

WC1, also known as T19, is the only unique gamma/delta T-cell differentiation antigen described to date other than the gamma/delta T-cell receptor. We present evidence that modulation of WC1 results in augmented proliferation of gamma/delta T cells. Immobilized IL-A29, a monoclonal antibody (mAb) specific for WC1, augmented proliferation of gamma/delta T cells in the autologous mixed leucocyte reaction (AMLR) as well as proliferation induced by either anti-CD3 or anti-CD5 mAb. In contrast, anti-CD5 mAb did not increase proliferation in the AMLR even though both CD5 and WC1 are members of the scavenger receptor cysteine-rich family of proteins and are expressed by bovine peripheral blood gamma/delta T cells. IL-A29 did not induce proliferation when assessed alone or in the presence of either phorbol myristate acetate (PMA) or interleukin-2. IL-A29 also did not induce detectable calcium mobilization when evaluated in the presence of monocytes, PMA, or following cross-linking of IL-A29 with anti-immunoglobulin antibody. We conclude that WC1 is a gamma/delta T-cell lineage-specific cell-surface differentiation antigen which is involved in activation of gamma/delta T cells using an as yet unidentified pathway.

A Novel T-Cell Differentiation Antigen Expressed in Immature Human Thymocytes and Neuroglial Cells

We report a novel human thymocyte differentiation antigen ICT-1 with a molecular weight of 49 kDa that is noncovalently associated with another 12-kDa protein. The ICT-1 antigen is expressed in 50-70% of total thymocytes, but not in resting or PHA-activated peripheral blood T-cells and bone marrow cells. The thymocytes expressing ICT-1 antigen appear after the 18th week of gestation during fetal development. Since the distribution pattern of the ICT-1 antigen within thymus partly overlaps with that of the CD1 antigens, we investigated whether ICT-1 was one of the CD1 antigen family. However, the failure of anti-ICT-1 antibody to react with mouse L cells transfected with cDNA of CD1a, -b, and -c and the different histologic distribution patterns from that of CD1d strongly suggest that the anti-ICT-1 antibody recognizes an antigen distinct from CD1. Furthermore, ICT-1 is also expressed in human neuroglial cells such as oligodendroglioma, glioblastoma multiforme, Ewing's sarcoma, and cerebellar astrocyte. Hence we believe that the ICT-1 antigen may be a novel thymus-leukemia (TL) antigen or a nonclassical MHC class I antigen.

Major expansion of CD8+ T cells with a predominant Vβ usage during the primary immune response to HIV

A SIGNIFICANT proportion (up to 70%) of individuals experience an acute clinical syndrome of varying severity associated with primary infection with the human immunodeficiency virus (HIV). We report here studies on six individuals who showed an acute HIV syndrome which generally resolved within four weeks, concomitant with a dramatic downregulation of viraemia. To characterize the T-cell-mediated primary immune response to HIV, we used combined semiquantitative polymerase chain reaction assay and cytofluorometry to analyse the T-cell antigen receptor repertoire in sequential peripheral blood mononuclear cells from the patients. We found major oligoclonal expansions in a restricted set of variable-domain beta-chain (V beta) families. Cells expressing the expanded V beta s predominantly expressed the CD8 T-cell differentiation antigen and mediated HIV-specific cytotoxicity. Major oligoclonal expansions of these CD8+ T lymphocytes may represent an important component of the primary immune response to viral infections and may help to clarify both the immunopathogenic and the protective mechanisms of HIV infection.

Regulation of T-cell lymphokine gene transcription by the accessory molecule CD28.

T-cell activation results in the production of multiple lymphokines. Efficient lymphokine gene expression appears to require both T-cell antigen receptor (TCR) signal transduction and an uncharacterized second or costimulatory signal. CD28 is a T-cell differentiation antigen that can generate intracellular signals that synergize with those of the TCR to increase T-cell activation and interleukin-2 (IL-2) gene expression. In these studies, we have examined the effect of CD28 signal transduction on granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin 3 (IL-3), and gamma interferon (IFN-gamma) promoter activity. Stimulation of CD28 in the presence of TCR-like signals increases the activity of the GM-CSF, IL-3, and IFN-gamma promoters by three- to sixfold. As previously demonstrated for the IL-2 promoter, the IL-3 and GM-CSF promoters contain distinct elements of similar sequence which specifically bind a CD28-induced nuclear complex. Mutation of the CD28 response elements in the IL-3 and GM-CSF promoters abrogates the CD28-induced activity without affecting phorbol ester- and calcium ionophore-induced activity. UV cross-linking indicates that the CD28-induced nuclear complex contains polypeptides of approximately 35, 36, and 44 kDa. These studies indicate that the TCR and CD28-regulated signal transduction pathways coordinately regulate the transcription of several lymphokines and that the influence of CD28 signals on transcription is mediated by a common complex.

Regulation of T-cell lymphokine gene transcription by the accessory molecule CD28.

T-cell activation results in the production of multiple lymphokines. Efficient lymphokine gene expression appears to require both T-cell antigen receptor (TCR) signal transduction and an uncharacterized second or costimulatory signal. CD28 is a T-cell differentiation antigen that can generate intracellular signals that synergize with those of the TCR to increase T-cell activation and interleukin-2 (IL-2) gene expression. In these studies, we have examined the effect of CD28 signal transduction on granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin 3 (IL-3), and gamma interferon (IFN-gamma) promoter activity. Stimulation of CD28 in the presence of TCR-like signals increases the activity of the GM-CSF, IL-3, and IFN-gamma promoters by three- to sixfold. As previously demonstrated for the IL-2 promoter, the IL-3 and GM-CSF promoters contain distinct elements of similar sequence which specifically bind a CD28-induced nuclear complex. Mutation of the CD28 response elements in the IL-3 and GM-CSF promoters abrogates the CD28-induced activity without affecting phorbol ester- and calcium ionophore-induced activity. UV cross-linking indicates that the CD28-induced nuclear complex contains polypeptides of approximately 35, 36, and 44 kDa. These studies indicate that the TCR and CD28-regulated signal transduction pathways coordinately regulate the transcription of several lymphokines and that the influence of CD28 signals on transcription is mediated by a common complex.

Somatic gene therapy for diabetes with an immunological safety system for complete removal of transplanted cells.

To develop somatic gene therapy for diabetes, we studied an animal model with proinsulin-producing fibroblasts with an immunological safety system. Cultured mouse fibroblasts of the Ltk- cell line were transfected first with the efficient human proinsulin expression vector pBMG-Neo-Ins. Initially, 2 x 10(6) cells with a proinsulin-production rate of 91 ng.24 h-1.10(6) cells-1 were transplanted i.p. into streptozocin-induced diabetic C3H mice. The blood glucose concentrations improved between the first and the 28th day, but the animals died of hypoglycemia between the 29th and 46th days. The proinsulin-producing Ltk- cells were further transfected with a second plasmid, pHEBo-CD8.2, encoding BALB/c mouse T-cell differentiation antigen. The CD8.2 allotype is different from CD8.1 allotype by only one amino acid substitution and should be only slightly antigenic to the recipient C3H mice. Somatic gene therapy with these doubly transfected cells followed by the consecutive administration of a monoclonal antibody to CD8.2 resulted in an initial decrease of blood glucose concentrations followed by the permanent recurrence of hyperglycemia, thus proving the complete removal of the transplanted cells. Cultured fibroblasts were thus proven capable of supplying sufficient proinsulin to lower the blood glucose concentrations in diabetic animals. The immunological safety system with a combination of artificial expression of cell surface antigen and the administration of the specific monoclonal antibody was an effective safety system for somatic gene therapy.

Cutaneous lymphomas of phenotypically undetermined lineage: Contribution of genotypic analysis

Genotypic analyses were performed in six primary cutaneous lymphomas whose lineage could not be assessed on the basis of histologic and phenotypic data. By immunophenotyping, these neoplasms expressed leukocyte common antigen and HLA-DR but did not show consistent immunostaining for B-cell or T-cell differentiation antigens. Expression of nonspecific histiocytic markers such as lysozyme and alpha 1-antitrypsin was found in three cases. By genotyping, three cases retained a germline configuration and immunoglobulin gene rearrangement was observed in one case, T-cell receptor gene rearrangement was found in one case, and both types of rearrangements in one case. Of the three patients in whom gene rearrangements were noted, two rapidly died and the other patient, with a dual genotype, is still alive 15 years after diagnosis. The three patients without gene rearrangements are alive and well after a mean follow-up of 2.5 years. It appears that cutaneous lymphomas with an uncertain phenotype include at least some cases of authentic B-cell or T-cell lymphomas. The germline configuration that we observed in cases with a chronic course remains difficult to explain. It may be related to a low malignancy form of histiocytic lymphoma, an atypical polyclonal hyperplasia, or even a low-grade lymphoma arising from a primitive cell without established commitment to either B- or T-cell lineage.

Significance of aberrant immunophenotypes in childhood acute lymphoid leukemia

Leukemic cells from 51 pediatric patients (younger than 18 years) diagnosed with acute lymphoid leukemia by standard morphologic and cytochemical methods were subjected to flow cytometric studies using a panel of monoclonal antibodies against T-cell (CD1, 2, 3, 4, 5, 7, 8), B-cell (CD10, 19, 20, 21), myeloid (CD13, 14, 15, 33), and HLA-DR antigens. Cases of "conventional" acute lymphoid leukemia (leukemic cells with a normal configuration of B-cell or T-cell differentiation antigens) were observed in 26 of 51 (51%) cases, whereas cases of "aberrant" acute lymphoid leukemia (cells with abnormal patterns of B-cell or T-cell antigens or with concomitant myeloid antigens) were noticed in 25 (49%) cases. Myeloid antigen-positive acute lymphoid leukemia was observed in the leukemic cells of eight (16%) individuals. No significant differences were observed between conventional and aberrant ALL in the distribution of sex, age, leukocyte count, hemoglobin concentration, platelet count, blast count, French-American-British (FAB) type, lymphadenopathy, organomegaly, rate or duration of remission, or survival. When only myeloid antigen-positive cases were compared with myeloid antigen negative-cases, no significant correlations were observed except for duration of first remission (myeloid antigen positive, 26+ +/- 22 months; myeloid antigen negative, 40+ +/- 18 months; P less than 0.001), and duration of survival (myeloid antigen positive, 27+ +/- 24 months; myeloid antigen negative, 62+ +/- 17 months; P = 0.001). These data suggest that pediatric patients with ALL blasts possessing myeloid antigens may represent a high-risk group for length of remission and survival.

末梢性Ｔ細胞腫ようの免疫学的検討 表現型と予後の関係について

174 peripheral T-cell lymphomas, classified according to the updated Kiel classification (Suchi), were immunophenotypically studied with a panel of monoclonal antibodies reactive with T-cell differentiation antigens in cryostat section and/or cell suspension. By immunologic studies, 50% of the lymphomas were of helper/inducer (CD4) phenotype, 6% were of cytotoxic/suppressor (CD8) phenotype, 3% expressed both CD4 and CD8, 3% lacked both CD4 and CD8, and 36% were phenotypically undetermined because of an admixture of almost equal number of CD4- and CD8-positive cells. The phenotypically undetermined cases were more frequently noted in low grade lymphomas than in high grade tumors, and the latter often showed the loss of pan-T antigens, although there was no definite correlation between histologic category and immunophenotype. CD25, strongly detectable in anti-HTLV-1 antibody-positive cases, was negative or weakly expressed in anti-HTLV-1 antibody-negative cases. Anaplastic large cell lymphomas (LC-Ana) strongly expressed CD30, which was sometimes detectable in only blast-like cells of low grade tumors. 71% of the lymphomas expressed Ia antigens. In this series, the clinical data were available for 154 patients. For individual markers, the expression of CD30 and/or HLA-DR was associated with a longer actuarial survival (p<0.05 by the generalized Wilcoxon test), but, in the population excluding LC-Ana, the significant difference was undetectable between the groups with and without CD30. Further, the absence of CD25 or presence of CD3 and/or CD7 on tumor cells correlated with a relatively favorable prognosis, but not significantly. The detection of CD4 and/or CD8 had relatively little prognostic value.

The significance of Leu 8 negative T cells in lymphoid skin infiltrates: malignant transformation, selective homing or T-cell activation?

The expression of Leu 8 was studied on skin biopsies from a large group of patients with benign and malignant skin disorders and correlated with the expression of T-cell differentiation antigens and activation markers. The effect of in vitro stimulation of peripheral blood T cells and T-cell subsets on the expression of Leu 8 antigen was also determined. In all the skin diseases studied an inverse relationship was found between the proportions of cells expressing Leu 8 and HLA-DR. A deficiency of Leu 8 positive cells was not specific for mycosis fungoides, but was also found in several reactive dermatoses. Stimulation of peripheral blood cells with phytohaemagglutinin (PHA), concanavalin A (Con A), and anti-CD3-PMA resulted in a considerable decrease of Leu 8 antigen expression on day 3 in both CD4+ and CD8+ T cells. These data suggest that the low proportion of Leu 8+ T cells in mycosis fungoides and several reactive skin disorders is not related to malignant transformation or selective homing of Leu 8- T cells, but probably results from local T-cell activation.

Genotypic and Immunophenotypic Characterization of Two Human Light Chain– – Only B-Cell Non-Hodgkin's Lymphomas

Two atypical human non-Hodgkin's lymphomas (NHLs) that exhibited unusual genotypic and in situ immunophenotypic abnormalities are described. Immunophenotypically, both NHLs lacked surface Ig heavy chains. With the exception of the MB2 B-cell-associated antigen, no B- and T-cell differentiation antigen was detected in case 1. NHL 2 failed to show evidence of clonality by immunohistochemical analysis but revealed the presence of many B-lymphocytes with an abnormal phenotypic profile: CD19+, CD20+, CD22+, kappa-, lambda-, CD9-, CD10-, CD21-, and CD24-. Genotypic analysis indicated that both lymphomas derived from anomalously matured pre-B-cells that had rearranged the lambda or kappa light chain genes but not the Ig heavy chain gene. The neoplastic cells of the two NHLs resemble the light chain-only B-cells recently discovered, following Epstein-Barr virus immortalization, in the human bone marrow. The authors' data confirm, therefore, the existence of the light chain-only B-cells in the human hematopoietic compartment. Moreover, their results emphasize the conclusive role of the immunogenotypic analysis in defining clonality, lineage, and maturation abnormalities of such atypical NHLs.

Murine T-cell differentiation antigen CD8 is a direct substrate of protein kinase C

Murine T cell differentiation antigen CD8α (Lyt-2) is phosphorylated in vivo after phorbol 12-myristate 13-acetate (PMA) treatment of cells. Concanavalin A, dibutyryl cAMP and calcium ionophore are unable to stimulate phosphate incorporation into CD8α. Depletion of cellular protein kinase C (PKC) by prolonged PMA treatment abolished this phosphorylation, suggesting that PKC is required for this effect. Using the amino acid sequence derived from cloning CD8α, peptides encompassing both possible intracellular phosphorylation sites were made and used to test the ability of various kinases to phosphorylate CD8α sequences. Only the proximal serine peptide was a kinase substrate, and of PKC, cAMP-dependent kinase and the multifunctional calcium/calmodulin-dependent kinase, only PKC was able to phosphorylate this peptide. These studies provide the first definitive evidence that CD8α is a direct substrate of PKC.

Monoclonal antibody specific for bovine CD 5 antigen which enhances mitogen-induced blastogenesis and IL-2 production

This study reports on the functional characteristics of a bovine T-cell differentiation antigen recognized by the monoclonal antibody (mAb) 8C11. This mAb has previously been found to react with a 67-kD molecule shared by thymocytes and peripheral blood T cells and to be undetectable on the B cells of healthy animals. This antigen is also largely expressed on the B cells from bovine leukemia virus-infected animals. Molecules with a similar cell distribution have been described in other species (mouse, human, rat and sheep), and were termed CD5 molecules. In order to confirm the CD5-like nature of the target molecule recognized by 8C11, functional T-cell assays were carried out. We report here that this mAb, like its human and murine homologues, enhances the proliferative responses of T cells to mitogens or alloantigens but does not directly stimulate T-cell division. Moreover, we have shown an enhancing effect of this 8C11 mAb on bovine interleukin-2 production by concanavalin A-stimulated bovine peripheral blood mononuclear cells.

Genotypic Analysis in Large Cell Lymphomas Expressing a Restricted Set of Differentiation Antigens

Immunophenotyping and immunogenotyping were performed in a series of 8 large cell lymphomas exhibiting anaplastic or "histiocytic" morphology and displaying an uncertain phenotype due to a restricted number of differentiation antigens. 6 cases expressed the Ki-1 antigen. 4 cases expressed one or two B-cell markers and contained rearrangements of the immunoglobulin genes. One of them also exhibited a T-cell receptor (TCR) beta gene rearrangement. 3 cases expressed a single T-cell differentiation antigen. Among them, only 1 displayed both gamma and beta TCR gene rearrangement; 1 only contained a gamma TCR gene rearrangement and 1 completely lacked clonal rearrangements. The eight cases expressed an inconclusive immunophenotype due to an abundant population of reactive cells but showed an immunoglobulin gene rearrangement. In conclusion, 5 out of the 8 unusual lymphomas studied here could be characterized by immunogenotyping. This approach was, however, inconclusive in the 3 remaining cases, whose lineage and differentiation stage remain poorly defined.