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Biomedical subjects

L Moretta

Publications and source records attributed to L Moretta.

At least 163 records · Page 9Linked to original sources
PubMed1991

Bispecific monoclonal antibodies directed to CD16 and to a tumor-associated antigen induce target-cell lysis by resting NK cells and by a subset of NK clones.

CD16 surface antigens represent activatory molecules in CD3-16+ NK cells. In order to target NK cells against relatively NK-resistant ovarian carcinomas, we used an anti-CD16 monoclonal antibody (MAb) (VD4), together with an anti-ovarian carcinoma-associated antigen (MOV19), to construct biMAbs. To this end, hybrid hybridomas were generated by fusing a TK-deficient VD4 hybridoma mutant with a HGPRT-deficient MOV19 hybrid. Supernatants from hybrid hybridomas that had been selected in HAT medium were screened for their ability to induce a CD3-16+ NK clone to lyse an MOV19+ ovarian carcinoma cell line in a 4-hr 51Cr-release assay. The NMB.45 hybrid hybridoma secreted a biMAb which triggered lysis of MOV19+ but not of MOV19- target cells. Some degree of target cell lysis was also observed with MOV19 MAb (due to ADCC mechanisms), while the VD4 MAb was ineffective. HPLC fractionation of MAbs secreted by the hybrid hybridoma made it possible to identify 4 different peaks, one of which appeared to contain functional biMAb molecules. HPLC-purified biMAb (100 ng/ml) induced resting PBL to lyse the "NK-resistant" IGROVI ovarian carcinoma cell line. Fresh MOV19+ tumor cells were also lysed, although with lower efficiency. When IL-2-activated lymphocytes were used as a source of effectors, biMAb caused only minor increases in the IL-2-induced cytolytic activity. Further analyses of the effect of biMAb were performed at the clonal level. Among CD3-16+ NK cell clones, a clear enhancing effect could be observed only in GL183+ but not in GL183- clones. In CD3+ cytotoxic clones a triggering effect could be detected in one out of 4 TCR gamma/delta+ clones but not in TCR alpha/beta+ clones.

Antibodies, Monoclonal↗
PubMed1991

Molecular heterogeneity of the 1.0-kb T beta transcript in natural killer and gamma/delta lymphocytes.

The T cell receptor (TcR) beta chain is encoded by a 1.3-kb mRNA which contains variable (V), diversity (D), joining (J) and constant (C) regions. A shorter 1.0-kb transcript with C but no V sequences is found in thymocytes, alpha/beta and gamma/delta T lymphocytes and natural killer cells. The origin, clonal variability and function of this transcript is unknown. We isolated cDNA clones representative of the 1.0-kb mRNA from cDNA libraries of either polyclonal or clonal natural killer and gamma/delta lymphocytes. Ten different types of cDNA clones belonging to three separate groups were identified: (a) "J-C clones" consisting of one of five J beta regions and the corresponding C beta 1 or C beta 2 regions; (b) "D-J-C clones" composed of D beta 1/or D beta 2/J beta rearranged sequences and C beta 1 or C beta 2 sequences; (c) "5'C clones" made up of C beta 1 or C beta 2 regions preceded by the corresponding genomic 5' flanking region. The presence of recombination signal sequences in J-C and D-J-C clones suggests that the first derive from mRNA transcribed from promoters located in the 5' J region and the second from mRNA transcribed from promoters situated in the 5' D region. Nucleotide sequence analysis demonstrated that only three of the ten types of clones isolated had the potential to code a short cytoplasmic T beta protein with a variable D-J beta N terminus. These findings have implications for the mechanisms of T beta germ-line transcription and the function of the T beta transcripts.

Amino Acid Sequence↗
PubMed1991

A novel surface molecule expressed by long-term cultured T and natural killer cells is involved in cell activation.

Two monoclonal antibodies (mAb), termed ED6 and LD6, were obtained by immunizing mice with cytotoxic T cell lines expressing the T cell receptor (TcR) gamma/delta. These mAb were selected according to their ability to trigger the cytolytic program of the immunizing cell lines in a redirected killing assay. Both mAb recognized molecule(s) expressed on the surface of most long-term cultured TcR gamma/delta +, TcR alpha/beta + and CD3-CD16+ lymphocytes, while it was absent on resting peripheral blood lymphocytes. In addition both mAb reacted with neoplastic B cell lines, Epstein-Barr virus-transformed B cell lines, small cell lung cancer and glioma cell lines, while no surface reactivity was detected on ovarian, breast, colon and non-small cell lung cancer lines. The functional activity of these mAb was studied by two cytolytic assays. Both mAb were able to trigger the cytolytic program of CD3+TcR gamma/delta + polyclonal cell lines and of a CD3-CD16+ NK cell clone against the murine mastocytoma target cell line P815 (Fc receptor+) in a 4-h 51Cr-release assay. In addition, ED6 and LD6 hybridomas were lysed by TcR gamma/delta + effector cells while other hybridomas (obtained from the same fusion) were not lysed. ED6 and LD6 mAb (in the presence of submitogenic doses of the phorbol 12-myristate 13-acetate) also induced the secretion of interleukin 2 by ED6/LD6+ T cell clones expressing TcR gamma/delta or alpha/beta. mAb-induced surface antigen modulation experiments showed that the antigenic determinant recognized by ED6 and LD6 co-modulated, thus indicating that the two mAb probably recognize the same or closely associated molecules. The molecular characteristics of the antigen recognized by the mAb were investigated by Western blot analysis. The LD6 mAb recognized a major band of approximately 65 kDa, both under nonreducing and reducing conditions. These data indicate that ED6 and LD6 mAb recognize a novel non-lineage-specific activation antigen which is involved in the induction of the functional program of long-term cultured T or natural killer cells.

Animals↗
PubMed1991

Thymic origin of some natural killer cells: clonal proliferation of human CD3-16+ cells from CD3-4-8- thymocyte precursors requires the presence of H9 leukemic cells.

Purified CD3-4- thymocyte populations were cultured in the presence of interleukin-2 (IL-2) and peripheral blood lymphocytes (PBL) and/or tumor cell lines as a source of irradiated feeder cells. Maximal cell proliferation was obtained in the presence of a mixture of H9 leukemic cells and normal PBL. More importantly, under these culture conditions, 30%-50% of these cells were found to express CD16 surface antigen after 1-2 weeks of culture. Similar proportions of CD16+ cells could be detected in CD3-4- thymocyte populations that had been further depleted of CD16+ cells. Cloning of CD3-4-16- thymocytes under limiting dilution conditions resulted, in the presence of H9 cells, in more than 50% of CD16+ clones (cloning efficiency 3%-8%). Since some of the surface CD3- clones expressed cytoplasmic CD3 antigen, it has been possible to identify four distinct phenotypic groups of clones (CD16+cyCD3+, CD16+cyCD3-, CD16-cyCD3+, CD16-cyCD3-). Independently of their phenotype, all thymus-derived CD3- clones expressed a strong cytolytic activity against natural killer (NK)-sensitive and NK-resistant tumour target cells. In addition, following stimulation with phytohemagglutinin (PHA) and phorbol 12-myristate 13-acetate (or PHA alone) all clones released interferon-gamma and tumour necrosis factor-alpha, but not IL-2. Taken together, our data provide evidence that cells which share their phenotypic and functional properties with CD3-CD16+ NK cells can be derived from thymic precursors.

Antigens, CD↗
PubMed1991

Molecular and cellular analysis of human T lymphocytes expressing gamma delta T-cell receptor.

A minor subset of T lymphocytes expresses a CD3-associated TCR composed of gamma and delta chains. The majority of TCR gamma/delta+ cells lack surface CD4 and CD8 antigen and do not react with WT31 mAb. These negative criteria were utilized in early studies to identify TCR gamma/delta+ cells. More recently, mAb to TCR gamma/delta, selected in different laboratories, have permitted the direct identification of TCR gamma/delta+ cells and their subsets. TCR gamma/delta molecules were found to be heterogeneous in size and charge mobility. Two major forms of TCR gamma/delta could be identified that are characterized by the presence or absence of an inter-chain disulphide bond. Biochemical analysis originally suggested that a precise correlation existed between reactivity with BB3 or delta TCS1/A13 mAb and expression of a disulphide (C gamma 1-encoded) or non-disulphide linked (C gamma 2-encoded) form of TCR gamma/delta. However, more recent studies have indicated that these mAb react with the molecular product of V delta 2 or V delta 1, respectively, mAb directed to one or another form of TCR gamma/delta activate the functional program of the cell, leading to intracellular Ca++ mobilization, lymphokine production and triggering of the lytic machinery. Analysis of the target molecules for TCR gamma/delta-mediated recognition revealed that at least some TCR gamma/delta+ cells are capable of specific responses to (allo)antigen and that polymorphic determinants of class I molecules can be recognized (as shown by the specific lysis of P815 cells transfected with HLA-24 allele). Unlike TCR alpha/beta+ cells, TCR gamma/delta+ cells are homogeneously composed of cytolytic precursors, as shown by the analysis of a large panel of clones in both lectin-dependent and redirected killing assays. In spite of their LGL morphology, freshly isolated TCR gamma/delta+ cells do not lyse NK-sensitive targets but do so after exposure to rIL-2. A modest cytolytic activity, however, could be induced also in fresh cells by anti-TCR/CD3 mAb in a redirected killing assay. Analysis of the distribution of the subsets expressing different TCR gamma/delta types showed that BB3+ cells are prevalent in the peripheral blood and virtually absent in the thymus; in contrast, A13+ (delta TCS1+) cells represent the majority of TCR gamma/delta+ thymocytes. Electron microscopic analysis of fresh TCR gamma/delta+ cells showed an extended cytoplasm containing numerous electron-dense granules identifiable as primary lysosomes. Upon stimulation with IL-2, TCR gamma/delta+ cells, similar to other LAK cells, display an increase in their cytoplasmic granules together with a redistribution of cytoskeletal structures.(ABSTRACT TRUNCATED AT 400 WORDS)

Antibodies, Monoclonal↗
PubMed1990

In vitro expansion of CD3/TCR- human thymocyte populations that selectively lack CD3 delta gene expression: a phenotypic and functional analysis.

Highly purified CD1-3-4-8- human thymocytes were obtained by panning techniques combined with cell depletion with antibody-coated magnetic beads. Most of these cells expressed cytoplasmic CD3 antigen, as assessed by mAbs known to react with the CD3 epsilon chain. After culture with low doses of PMA (0.5 ng/ml) and subsequent addition (at 24 h) of recombinant interleukin 2 (rIL-2; 100 U/ml) cells underwent extensive proliferation (40-60-fold of the initial cell input after 2 wk). The majority of the proliferating cells were CD3-TCR-. The remaining cells (5-40%) were represented by CD3+ TCR gamma/delta+ (BB3- A13+) cells. Further removal of CD3+ TCR-gamma/delta+ cells resulted in highly purified CD3- populations that further proliferated in culture with no substantial phenotypic changes. When CD3+ thymocytes were cultured under the same experimental conditions, only CD3+ TCR-alpha/beta+ cells could be detected, thus indicating that PMA did not affect the surface expression of the CD3/TCR complex, but rather induced preferential growth of CD3- thymocytes. Surface marker analysis of cultured CD3- thymocytes showed that they were homogeneously CD7+, whereas low proportions of cells expressed CD2 and CD8 antigens. Among the natural killer (NK) cell markers, CD56 was highly expressed by all cells, whereas CD16, CD57, CD11b, NKH2, and GL183 were absent. Importantly, these cells were different from peripheral NK cells, as 80-95% of them expressed cytoplasmic CD3 antigen. Functional analysis revealed a strong cytolytic activity against both NK-sensitive (K562) and NK-resistant (M14, Daudi) human target cells. In a redirected killing assay against the Fc gamma R+ P815 cells, mAbs specific for triggering molecules including CD3, CD2, and CD16 failed to augment target cell lysis, while a strong cytolytic effect was induced by PHA. In addition, PHA alone or in combination with PMA induced tumor necrosis factor alpha (TNF-alpha) and interferon gamma (IFN-gamma) (but not IL-2) production by CD3- thymocytes. Cloning of fresh CD1-3-4-8-thymocytes in the presence of PMA and rIL-2 resulted in CD3-CD56+ clones that displayed a pattern of cytolytic activity and lymphokine production similar to that of the polyclonal populations. Northern blot analysis of transcripts coding for CD3/TCR molecules revealed the presence of CD3 zeta, epsilon, and gamma transcripts, while CD3 delta was undetectable. Mature transcripts for both gamma and delta TCR chains could be detected, whereas no TCR-alpha mRNA and only a truncated (1.0 kb) form of TCR-beta mRNA were revealed.(ABSTRACT TRUNCATED AT 400 WORDS)

Antigens, CD↗
PubMed1990

The C gamma 1-encoded disulphide-linked and the C gamma 2-encoded nondisulphide-linked forms of the gamma/delta heterodimer use different gamma and delta variable regions.

We identified two types of gamma/delta T-cell clones: (1) BB3+ clones, which express the disulphide-linked form of the gamma/delta heterodimer (type 1 receptor) and carry rearrangements of the C gamma 1 gene; and (2) delta TCS1+ clones, which express the nondisulphide-linked form of the gamma/delta heterodimer (type 2 receptor) and carry rearrangements of the C gamma 2 gene. To determine the joining (J) and variable (V) region usage of the two receptor types, T gamma and T delta gene rearrangements and expression were analyzed in each gamma/delta T-cell clone. The results showed that the J and V regions used by the two receptor types are distinct: clones that express the type 1 receptor carry potentially functional rearrangements in J gamma P-V gamma 9 for gamma and in J delta 1-V delta 2 for delta; and clones that express the type 2 receptor had potentially functional rearrangements in J gamma 2-V gamma 2/V gamma 4 for gamma and in J delta 1-V delta 1 for delta. Therefore, two clearly different gamma/delta receptors (V gamma 9-J gamma P-C gamma 1/V delta 2-J delta 1-C delta and V gamma 2/V gamma 4-J gamma 2-C gamma 2/V delta 1-J delta 1-C delta) predominate in peripheral blood.

Adult↗
PubMed1990

Specific recognition of human CD3-CD16+ natural killer cells requires the expression of an autosomic recessive gene on target cells.

We analyzed the recently defined ability of CD3-CD16+ cells to specifically recognize and lyse normal allogeneic target cells (PHA-induced blasts). The susceptibility to lysis by a given alloreactive natural killer (NK) clone ("1 anti-A") was expressed by PHA blasts derived from 9 of 38 random donors analyzed. In all instances, the specific lysis of "susceptible" target cells was greater than 35% while that of "nonsusceptible" targets was less than 6% at an E/T cell ratio of 5:1. In addition to 1 anti-A, A anti-1 specific CD3-CD16+ clones could also be isolated from the reverse MLC combination. The relationship existing between lysis of normal allogeneic cells or tumor cells by the same CD3-CD16+ effector cell has been investigated: 1 anti-A specific CD3-CD16+ clones lysed PHA blasts of three of six cancer patients, while they lysed fresh tumor cells (ovarian carcinoma) from all six patients. The type of inheritance of the character "susceptibility to lysis" was analyzed in representative families. This analysis revealed that the character is inherited in an autosomic recessive fashion, and it is therefore different from MHC. We further investigated the type of segregation of the opposite character "resistance to lysis" (which is inherited in a dominant mode). The finding that this character segregated in all donors expressing given MHC haplotypes indicated that the gene regulating the expression of the NK-defined alloantigen is present on chromosome 6.

Antibodies, Monoclonal↗
PubMed1990

Cytolytic function of clonable T cells after human bone marrow transplantation.

We evaluated T-cell mediated lymphokine activated killer (LAK) function during the late (greater than 5 months) reconstitution phase after T cell-depleted allogeneic bone marrow transplantation (BMT) for hematologic malignancy. Since LAK cells are sustained by interleukin-2 (IL-2), we also investigated the ability of post-BMT T cells to produce IL-2. These functions were investigated at the clonal level. More than 200 T-cell clones from six long-term BMT recipients were generated and compared with 60 T-cell clones derived from two normal controls. Almost all the CD8+ clonal cultures from BMT recipients expressed cytolytic activity in a lectin-dependent cellular cytoxicity assay. Interestingly, a higher proportion of BMT recipient-derived cytolytic clones were able to mediate LAK activity in comparison with control clones (28% versus 4%, P less than .05). However, T-cell clones from BMT recipients, as opposed to control clones, were largely incapable of producing IL-2. Given the high proportions of post-BMT circulating CD8+ T cells, it appears that, in long-term BMT recipients, the precursors of nonspecific LAK effectors are present at above normal levels. However, their function may be defective in vivo due to poor IL-2 production.

Bone Marrow Transplantation↗
PubMed1990

A novel surface antigen expressed by a subset of human CD3- CD16+ natural killer cells. Role in cell activation and regulation of cytolytic function.

The GL183 mAb was obtained by immunizing BALB/c mice with the E57 clone (CD7+CD2+CD3-CD16+CD56+) derived from human peripheral blood NK cells. In human peripheral blood, GL183-reactive cells ranged between 2 and 12% (mean 6.5%) in 10 different donors. Double fluorescence and FACS analysis showed that GL183+ cells were consistently included in the CD56+ or CD16+ cell populations. Moreover, since only a fraction of CD56+ or CD16+ cells (approximately 40%) coexpressed GL183 surface antigen, reactivity with GL183 mAb appears to define two subsets within the CD3- lymphocyte population expressing NK cell markers. Although, the majority of GL183+ cells were CD3-, approximately 1% expressed CD3 surface antigens. As shown by clonal analysis, these infrequent CD3+GL183+ cells coexpressed CD56 and CD16 antigens. Cloning of CD3-GL183+ or CD3-GL183- cell populations under limiting dilution conditions yielded clonal progenies that maintained their original surface phenotype. Therefore, expression or lack of expression of GL183 surface antigens represents a stable phenotypic property of a subset of human CD3- NK cells. Immunoprecipitation experiments and two-dimensional PAGE analysis indicated that GL183-reactive molecules were represented in different clones either by a single 58-kD chain or, more frequently, by two chains of approximately 55 and approximately 58 kD, respectively. Analysis of GL183+ or GL183- NK clones for their ability to lyse human (IGROV I) or murine (P815) tumor target cells indicated that GL183- clones were, on average, fivefold more efficient in inducing target cell lysis. GL183+ and GL183- clones produced comparable levels of TNF-alpha in response to PHA plus PMA or anti-CD16 mAb plus PMA. Importantly, production of TNF-alpha was also induced by stimulation of GL183+ clones with GL183 mAb plus PMA. These data indicated that GL183 antigen could mediate cell triggering. This concept was confirmed by the analysis of Ca2+ mobilization, as GL183 mAb induced (in GL183+ clones) increments of [Ca2+]i comparable with those induced by PHA. Moreover, GL183 mAb, or its F(ab')2 fragments, strongly enhanced the cytolytic activity of GL183+ clones against a panel of human tumor target cells, including U937, Raji, IGROV I, M14, and A549. In contrast, GL183 mAb, but not the F(ab')2 fragments, sharply inhibited the cytolytic activity of the same clones against P815, M12, and P3U1 murine target cells. In this case, the effect of GL183 mAb (inhibition) was opposite that of PHA or of stimulatory anti-CD2 or anti-CD16 mAbs, which consistently enhanced the target cell lysis.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1990

Natural killer cells carry the germ-line configuration of the T cell receptor delta chain gene and heterogeneously express six distinct delta transcripts.

Investigations on T cell receptor delta chain (TcR delta) gene expression in freshly isolated normal large granular lymphocytes, natural killer (NK) cell clones and NK bulk cultures revealed six T delta transcripts (3.5, 3.1, 2.2, 2.0, 1.5 and 1.3 kb) which varied in number and relative abundance in the different samples. None of the six known T delta variable regions was expressed and the T delta locus was retained in its germ-line configuration. The origin and significance of these NK-associated T delta transcripts are discussed.

Antigens, Differentiation, T-Lymphocyte↗
PubMed1990

A novel pathway of human B cell activation initiated by CK226 surface antigen.

In this study we analyzed the effect of CK226 monoclonal antibody (mAb) on human B cell activation and proliferation. This mAb was shown to recognize a 75-kDa surface molecule expressed on both T and B lymphocytes and to mediate T lymphocyte activation and proliferation. Flow cytometry analysis of B cell populations isolated from peripheral blood, tonsil and spleen showed that CK226 surface antigen is highly expressed on 40-80% of surface Ig+ cells. When purified B cells were cultured in the presence of CK226 mAb, up-regulation of major histocompatibility complex class II and CD23 surface structures and the de novo expression of CD25 antigen could be detected within 48 h. In addition, B cells underwent proliferation ([3H] thymidine uptake) in the absence of either T cells or exogenous lymphokines. Proliferation was potentiated by the addition of suboptimal concentrations (0.5 ng/ml) of phorbol 12-myristate 13-acetate (PMA). Cells recovered at day 5 were surface Ig+ and no CD3+ cells could be detected. CK226-induced proliferation (either in the presence or in the absence of PMA) was not inhibited by anti-CD25 mAb. Addition of exogenous interleukin 2 to CK226-stimulated B cells resulted in further increase of B cell proliferation. On the other hand, CK226 mAb did not display a co-stimulatory effect with submitogenic concentrations of either anti-Ig antibody or Staphylococcus aureus Cowan strain I bacteria. In addition proliferation induced by mitogenic concentrations of the above stimuli was inhibited in a dose-dependent fashion by CK226 mAb.

Antibodies, Anti-Idiotypic↗
PubMed1990

T gamma delta-cell subsets in cord and adult blood.

A minor population of T cells expresses a heterodimeric antigen receptor composed of gamma and delta chains (TcR-1). In blood from adults, two subsets of T gamma delta cells can be identified by the monoclonal antibodies (MoAb) BB3 and A13. Little is known about the distribution and markers of these subsets early in life. We have therefore examined both the frequencies of these cells in cord blood and their expression of the cytotoxicity-associated marker serine esterase (SE), using immunocytochemical techniques. Our data show lower percentages of TcR-1+ cells in the blood of newborns compared with that in adults. However, the ratio of the A13+/BB3+ cells was significantly higher in cord than in adult blood. Whereas virtually all the adult TcR-1+ cells in blood were SE-positive, only a small proportion of the cord blood cells carried this enzyme. This was restricted to the BB3+ T gamma delta-cell subset in the cord. Our data suggest different characteristics of the TcR-1+ cells in blood from newborns compared with adult blood, and study of the functions of the different subsets, e.g. cytotoxicity, will be important in understanding their particular role in immunity.

Adult↗
PubMed1990

T gamma delta cells and their subsets in blood and synovial tissue from rheumatoid arthritis patients.

We have examined the frequencies of T gamma delta cells in blood, synovial fluids, and synovial membranes of patients with rheumatoid arthritis (RA) and in blood from age-matched controls. Immunocytochemical and immunohistochemical techniques were used with monoclonal antibodies BB3 and A13 to define a major and minor blood subset of T gamma delta cells respectively. Together, these antibodies identify the majority (if not all) of the peripheral blood T gamma delta cells. Significantly lower levels of T gamma delta cells were found in the blood of RA patients compared with controls, whilst higher but not significant numbers were found in the synovial fluids of paired samples. Scattered T gamma delta cells were found only in some synovial membranes with a distribution similar to the T alpha beta cells. Analysis of the two different T gamma delta-cell subsets indicated a ratio of BB3 to A13 of about 5:1 in control and RA blood. However, this ratio was less than 1:1 in the RA synovial fluids and membranes. The migratory nature of the A13+ cells could account for their predominance in these sites. The possible pathological significance of these cells in the rheumatoid synovial fluid and synovial membranes is discussed.

Adult↗
PubMed1990

Molecular studies on LAK cells.

We have developed a culture system for long-term growth of human LAK cells exhibiting an elevated, wide-spectrum anti-tumor cytotoxicity. The phenotypic and molecular properties of the final LAK cell populations indicated that they consist of three main types: a) NK-like lymphocytes (type I): NKH-1+, Ti alpha/beta-, Ti gamma/delta-, CD3-lymphocytes carrying the germline configuration of all TCR genes and expressing variable amount of the 1.0 beta mRNA and variably sized T delta transcripts; b) gamma/delta-like T lymphocytes (type II) NKH-1+, Ti alpha/beta-, Ti gamma/delta+, CD3+ lymphocytes carrying polyclonal rearrangements of the gamma and delta genes and expressing high levels of mature gamma and delta transcripts; c) alpha/beta-like T lymphocytes (type III): NKH-1+, Ti alpha/beta+, Ti gamma/delta-, CD3+ lymphocytes carrying rearrangements of all TCR genes and expressing high levels of mature alpha and beta transcripts. We took advantage of the high number of available LAK cells to clarify: 1) the origin of the NK-LAK delta transcripts. delta gene expression in LGL, NK clones and type I LAK cultures revealed six delta transcripts (3.5, 3.1, 2.2, 2.0, 1.5 and 1.3 kb), which varied in number and relative abundance in the different samples. None of the six known V delta was expressed and the delta locus was retained in its germline configuration suggesting that the delta expression is due to a partially rearranged or germline transcripts; 2) the origin of the NK-LAK truncated T beta transcript. We isolated two different clone types from a type I LAK cell cDNA library: a) J-C clones consisting of one of three J beta regions and the corresponding C beta 1 or C beta 2 regions; b) X-J-C and C-X clones, containing as yet unidentified (X) sequences. The presence of RSSs in J-C clones suggests that they derive from mRNAs transcribed from a promoter in the 5'J. Nucleotide analysis demonstrated that only one of the isolated clones had the potential to code a short T beta protein.

Amino Acid Sequence↗
PubMed1990

Human lymphocytes expressing a TCR gamma/delta.

A minor subset of T lymphocytes express a TCR composed of gamma and delta chains. This subset differs from conventional T cells for a number of phenotypic and functional characteristics. TCR gamma/delta + cells simultaneously lack both CD4 and CD8 antigens. Cloning of CD4-8-peripheral blood lymphocytes, under limiting dilution conditions, revealed that they are homogeneously composed of cytolytic cells which efficiently lyse tumor target cells. Formal proofs have been provided that TCR gamma/delta + cells are able to recognize antigens. For example, they proliferated in response to allogeneic mixed lymphocyte culture (MLC), in addition MLC-derived TCR gamma/delta + cells specifically lysed PHA-induced blast cells bearing the stimulating alloantigens. The selection of monoclonal antibodies (MoAbs) specific for TCR gamma/delta molecules allowed to identify two distinct subsets of TCR gamma/delta + cells. These MoAbs, termed BB3 and delta-TCS-1 (or the equivalent A13) respectively, induced specific activation of cloned cells expressing the corresponding antigenic determinants (as assessed by measurements of intracellular Ca2+ and/or lymphokine production of cytolytic activity). Analysis of the distribution of subsets expressing different forms of TCR gamma/delta, showed that the BB3-reactive form is prevalent in the peripheral blood. In contrast, delta-TCS-1-reactive cells are relatively infrequent in peripheral blood, but represent the majority of TCR gamma/delta + in the tissues.

Animals↗