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S Ferrini

Publications and source records attributed to S Ferrini.

At least 73 records · Page 4Linked to original sources
PubMed1994

Characterization of a cyclosporin A-sensitive activation pathway in cultured T and natural killer cells.

Previously, the authors have described a molecule, identified by the LD6 monoclonal antibody (MoAb), present at the cell surface of long-term cultured T and Natural Killer (NK) cells which is involved in cell triggering. In the study described here the authors used biotin surface labelling and immunoprecipitation to show that LD6 MoAb recognizes a surface protein of approximately 65 kDa. In combination with submitogenic concentrations of phorbol esters (PMA); LD6 MoAb was able to induce accumulation of mRNA specific for GM-CSF, gamma-IFN and TNF-alpha and release of these cytokines by LD6+ T-cell lines. Both lymphokine production and lymphokine-specific mRNA accumulation induced by the LD6 MoAb were blocked totally by Cyclosporin A (CsA). To investigate the mechanism(s) of signal transduction through this activatory pathway, the authors performed Ca++ mobilization experiments. The results of these experiments suggested a role for Ca++ in signal transduction. The Ca++ mobilization induced by LD6 MoAb cross-linking could be inhibited totally by the use of pertussis toxin, indicating a possible role for G proteins in signalling through the LD6 MoAb-reactive molecule. Western blot analysis performed with an anti-phosphotyrosine antibody did not suggest that tyrosine kinase activation has a role.

Antibodies, Monoclonal↗
PubMed1993

Targeting of T lymphocytes against EGF-receptor+ tumor cells by bispecific monoclonal antibodies: requirement of CD3 molecule cross-linking for T-cell activation.

Targeting of T lymphocytes against epidermal growth-factor-receptor (EGF-R)+ tumor cells was achieved by constructing a hybrid hybridoma which secretes an anti-EGF-R/anti-CD3 bispecific monoclonal antibody (biMAb) of hybrid isotype (IgG1/IgG2a). Purification of biMAb molecules from parental anti-EGF-R and anti-CD3 MAbs was performed by protein-A chromatography. The purified biMAb was able to trigger the lysis of EGF-R+ tumor cell lines (A431, IGROV-1, MDA-468 and U-87) and of NIH-3T3 transfectants expressing human EGF-R by cytolytic T lymphocytes, but it was ineffective in the case of EGF-R-negative tumor targets. Normal EGF-R+ cells (keratinocytes and endometrial cells) were also susceptible to biMAb-targeted cytolysis. However, the amount of biMAb required to induce half-maximal cytolysis of tumor cells over-expressing the EGF-R molecule (A431) was considerably lower than that required to induce lysis of EGF-R+ tumor or normal cells which express EGF-R at considerably lower density. The ability of such biMAbs to deliver activation signals to T cells was evaluated by Ca++ mobilization and lymphokine production experiments. The soluble anti-EGF-R/anti-CD3 biMAb failed to induce intracellular Ca++ increases, which occurred only after cross-linking induced by an anti-mouse IgG antibody. Secretion of lymphokines (IFN-gamma, TNF-alpha and GM-CSF) was induced by contact of the biMAb-coated effector cells with the relevant tumor target, whereas the soluble biMAb was virtually ineffective. In addition, biMAb-coated effector cells retained the ability to recognize and to lyse EGF-R+ tumor cells for a prolonged period of time. Our data indicate that activation of effector cells targeted by biMAbs can only occur at the tumor site, where cross-linking of surface CD3 molecules is induced by contact with the tumor cells.

Antibodies, Bispecific↗
PubMed1993

Human CD3-CD16+ natural killer cells express the hGATA-3 T cell transcription factor and an unrearranged 2.3-kb TcR delta transcript.

In this study we analyzed the T cell receptor(TcR) delta transcripts expressed by CD3-CD16+ cells and we investigated whether these cells expressed the hGATA-3 T cell transcription factor and the recombination-activating gene (RAG)-1. Multiple TcR delta transcripts deriving from an unrearranged TcR delta gene were detected in both polyclonal and clonal CD3-CD16+ natural killer(NK) cell lines. Two unrearranged TcR delta transcripts had a size similar to that of the functional TcR delta mRNA (2.3 and 1.3 kb) found in TcR gamma/delta+ T lymphocytes. Sequence analysis of nine different 2.3-kb cDNA clones obtained from NK-derived polyA+ RNA confirmed that they corresponded to an unrearranged TcR delta gene. These cDNA were 2343 bp long and their transcription initiation site was located 814 bp upstream from the J delta 1 segment. The sequence located upstream of the J delta 1 segment corresponded to the previously reported germ-line sequence. The J delta 1 segment was correctly spliced to C delta; in addition the four C delta exons were found to be already assembled. Two polyadenylation sites were present in the fourth C delta exon. However, only that located at the 3' end appeared to be utilized in the 2.3-kb cDNA. The expression of hGATA-3, a T cell-specific factor known to be involved in the regulation of the transcription of TcR delta locus, was analyzed by Northern blot, in cultured NK cell population and clones (but not in freshly derived cell populations). All NK clones and cell lines studied were found to express hGATA-3-specific mRNA, suggesting that hGATA-3 may be involved in the regulation of the unrearranged TcR delta gene expression in NK cells. Finally, no transcription of the RAG-1 gene could be detected in all NK cell lines or clones analyzed.

Base Sequence↗
PubMed1993

The protective effects of N-acetyl-L-cysteine against methyl mercury embryotoxicity in mice.

N-Acetyl-L-cysteine (NAC) has been widely used in the protection against the toxic effects produced by several chemicals because of its radical scavenger properties and because NAC is a precursor of glutathione, one of the most important intracellular defenses against oxidants. The aim of this investigation was to verify the potential protective activity of NAC against the well-known embryotoxicity induced by methyl mercuric chloride (MMC) in mice. Three experimental approaches were carried out. In the first investigation, acute treatment of MMC (25 mg/kg po) was given in CD female mice on Day 10 of pregnancy, and was followed immediately and/or after 24, 48, and 72 hr by administrations of NAC (800 mg/kg i.v.). The embryolethal effects caused by MMC poisoning were completely antagonized by just a single administration of NAC, while the incidence of palatoschisis was reduced in relation to the number of NAC administrations. In the second experiment MMC was chronically gavaged (3 mg/kg/day po) during the period of organogenesis on Days 5 to 14 of gestation. During the same period of time some of these females were also exposed to 1% NAC dissolved in drinking water. MMC poisoning reduced the body weight of viable fetuses and induced many cases of palatoschisis. The body weight of fetuses from MMC-poisoned mothers treated with NAC was improved and the incidence of palatoschisis was in the normal range. In the last experiment the treatment with NAC (400 mg/kg i.v., during the period of organogenesis) drastically reduced the severe embryolethality induced by MMC (6 mg/kg/day po) administered during the same period of time.(ABSTRACT TRUNCATED AT 250 WORDS)

Abnormalities, Drug-Induced↗
PubMed1993

Suramin-induced growth inhibition and insulin-like growth factor-I binding blockade in human breast carcinoma cell lines: potentially related events.

Suramin, a polyanionic drug used in the treatment of trypanosomiasis and onchocerciasis, inhibits growth factor-induced mitogenesis in several human tumours. We have investigated the effect of suramin on human breast cancer cell lines (HBCCL). By cell counts and thymidine incorporation we found that 50 to 400 micrograms/ml suramin inhibits the proliferation of HBCCL in a dose-dependent and reversible fashion (ID50 approximately 200 micrograms/ml for MCF-7 and MDA-MB 231). Radioreceptor and affinity cross-linking assays showed that suramin was also able to reduce the binding of insulin-like growth factor I (IGF-I) to its receptor (40-50% inhibition at 100 micrograms/ml). Our results indicate that the drug does not affect the IGF-I receptor (IGF-I-R), but binds directly to the IGF-I peptide. In conclusion, the strict correlation observed between suramin inhibition of proliferation and IGF-I binding on HBCCL suggests a possible therapeutic role for this molecule as an antineoplastic drug in human breast tumours.

Breast Neoplasms↗
PubMed1993

Targeting of saporin to CD25-positive normal and neoplastic lymphocytes by an anti-saporin/anti-CD25 bispecific monoclonal antibody: in vitro evaluation.

This study has been designed to verify the specific toxicity of saporin, a type 1 ribosome-inactivating protein (RIP), with the same activity as ricin A chain, targeted by a bispecific monoclonal antibody (bimAb) recognising both the CD25 antigen and the RIP. The CD25 antigen is expressed by lymphoid populations upon activation and by leukaemias and lymphomas with an activated membrane phenotype (Hodgkin's lymphoma, anaplastic large cell lymphoma, adult T cell leukaemia). The bimAb-saporin mixture was tested on CD25+ targets at different bimAb and saporin concentrations. Saporin, in the presence of a bimAb concentration of 10(-9) M, inhibited protein synthesis by CD25+ neoplastic lymphocytes (L540 and MT2 cell lines) with IC50S (concentrations giving 50% of inhibition) ranging from 8 x 10(-12) M to 3 x 10(-11) M. The saporin-bimAb mixture was also effective in blocking the phytohaemagglutinin-driven proliferation of normal lymphocytes, whereas it displayed the same level of toxicity exerted by saporin alone on an irrelevant CD25-negative cell line (EBV-infected B lymphoblastoid cell line). From these results it is possible to envisage a clinical use of this bimAb as a cytotoxic agent for CD25+ leukaemias and lymphomas, as well as an immunosuppressive agent for severe immune disorders such as graft-vs-host disease (GVHD) and transplanted organ rejection.

Animals↗
PubMed1993

Cultured human NK cells express the Ki-1/CD30 antigen.

In this study we show that in vitro cultured human polyclonal NK cell lines and clones express the Ki-1/CD30 Hodgkin-associated antigen, identified by the BER-H2 monoclonal antibody. The percentage of BER-H2+ cells ranged from 19% to 67% in five polyclonal NK cell lines and was 31% and 20% in two NK clones. The intensity of BER-H2 mAb staining on cultured NK cells was remarkably lower than that found on the L540 Hodgkin's lymphoma cell line. Resting PBL populations that had been enriched for NK cells failed to react with the BER-H2 mAb. Western blot analysis performed on cell lysates from a polyclonal NK cell line and from the NK3.3 NK-like cell line revealed that BER-H2-reactive molecules consisted of two major bands of approximately 110 kD and 100 kD. Two bands displaying an identical electrophoretic mobility were also found in lysates of the L540 cell line. The BER-H2 mAb failed to inhibit the nonspecific activated killer activity of cultured NK cells against both K562 and MeWo tumour target cells. In addition, the BER-H2 mAb was unable to trigger the cytolytic activity of NK cells in a redirected killing assay. The observation that cultured human NK cells express the Ki-1/CD30 antigen may be of relevance for the possible lineage assignment of K11/CD30+ lymphoid cell neoplasia with unrearranged TCR genes.

Blotting, Western↗
PubMed1993

Use of anti-CD3 and anti-CD16 bispecific monoclonal antibodies for the targeting of T and NK cells against tumor cells.

To target T lymphocytes against EGF-R+ tumors, we constructed anti-CD3/anti-EGF-R bimAbs either by the generation of a hybrid hybridoma (quadroma) or by a chemical cross-linking method. Analysis of the in vitro functional activity of these two different constructs indicated that the quadroma-secreted bimAb was more efficient in targeting the CD3+8+ clones against EGF-R+ target cells with respect to the bimAb produced by chemical method. In addition, the quadroma-produced bimAb is able to induce cytolysis of EGF-R+ tumor cell lines of PHA-induced lymphoblasts that had been expanded in IL-2-containing medium, whereas tumor cells lacking expression of EGF-R were not lysed. Resting PBL targeted by the bimAb did not display significant cytotoxicity against the relevant tumor. An anti-CD16 hybridoma (IgG1) was fused with an anti-folate-binding protein hybrid (IgG2a) to construct bimAbs to target NK cells against NK-resistant ovarian carcinomas. The hybrid IgG1/IgG2a bimAb triggered the specific lysis of relevant target cells by resting NK cells, but it was ineffective when CD8+TCR alpha/beta+ cultured cell populations were used as effectors. Only marginal increases of cytolytic activity could be induced by the bimAb when IL-2-activated PBL (i.e., LAK cells) were used as effectors due to the high cytolytic activity of these cells against the relevant tumors in the absence of bimAb. The possible use of anti-CD16 or anti-CD3 bimAbs for the development of different cellular immunotherapy strategies against cancer is discussed.

Antibodies, Bispecific↗
PubMed1992

Targeting of "T" lymphocytes against human hepatoma cells by a bispecific monoclonal antibody: role of different lymphocyte subsets.

In an attempt to construct bispecific monoclonal antibodies (bimAbs) able to target cytotoxic T lymphocytes against human hepatoma cells, an HGPRT-deficient mutant of the Hepama-6 hybridoma, which produces an antihuman-hepatoma mAb, was directly fused with splenocytes from Balb/C mice immunized by a polyclonal cytotoxic T-cell line. Hybrid hybridomas were selected in HAT medium, and their supernatants were directly screened for the ability to induce IL-2-cultured cytotoxic T lymphocytes to kill hepatoma cells in a 51Cr-release assay. The selected hybrid hybridoma, termed DQ-33, secretes a bimAb, which reacts with a CD3-associated determinant. When resting peripheral-blood lymphocytes were used as effector cells, virtually no cytolytic activity could be induced by DQ-33, whereas phytohemagglutinin-activated lymphocytes that had been expanded in vitro in IL-2-containing medium could be efficiently targeted against hepatoma cells. Targeting by DQ-33 bimAb was analyzed on different subsets of IL-2-cultured lymphocytes. It was evident that CD+4-8+ TCR alpha/beta+ and CD3+4-8-TCR gamma/delta+ lymphocytes were efficiently induced by bimAb to lyse human hepatoma cells, whereas no induction of cytolysis could be observed when CD3 + 4 + 8-TCR alpha/beta+ cells were used as effectors. DQ-33 bimAb was also able to induce lymphokine secretion (IL-2, GM-CSF and TNF-alpha) by all the different subsets of lymphocytes analyzed in the presence of target cells expressing the relevant antigen, independent of the expression of cytolytic activity.

Antibodies, Monoclonal↗
PubMed1992

Selective increase of a subset of T cell receptor gamma delta T lymphocytes in the peripheral blood of patients with human immunodeficiency virus type 1 infection.

Increased proportions of the small lymphoid subset expressing T cell receptor (TCR) gamma delta occur in different infectious diseases, particularly in mycobacterial infections. In this study the two main subsets of TCR gamma delta+ cells in peripheral blood mononuclear cells (PBMC) of 54 patients with human immunodeficiency virus type 1 infection were analyzed. These subsets were defined by indirect immunofluorescence techniques and FACS analysis using BB3 and A13 monoclonal antibodies, which specifically react with V delta 2- and V delta 1-encoded forms of TCR gamma delta. The proportion of BB3+(V delta 2+) and A13+(V delta 1+) cells was analyzed in purified PBMC populations. Patients were stratified according to Walter Reed (WR) clinical stage. A sharp increase in percentage of A13+(V delta 1+) cells was observed in all stages of the disease. In addition, a strict correlation was found with stage of the disease and percentage of CD8+ PBMC. An inverse correlation was found with the proportion of CD4+ PBMC. An early (WR2) inversion of the V delta 2-to-V delta 1 ratio was consistently detected even before the inversion of the CD4-to-CD8 ratio.

CD4 Antigens↗
PubMed1992

TCR gamma/delta positive lymphocytes after allogeneic bone marrow transplantation.

Peripheral gamma/delta+ T cells were studied in patients following allogeneic bone marrow transplantation (BMT) by indirect immunofluorescence utilizing two monoclonal antibodies (G1 and A13) able to recognize the two major subpopulations (V delta 2+ and V delta 1+, respectively) of these cells. We found that the relative percentage of 'total' (gamma/delta+ T lymphocytes) (V delta 2 + V delta 1 positive cells), and particularly of G1+ (V delta 2+) cells, in CD3+ lymphocytes was higher in transplanted patients, and especially in those presenting with acute graft-versus-host disease (aGVHD), than in normal controls. This finding was confirmed by the analysis of the V delta 2+/V delta 1+ cell ratio which was again significantly higher in patients with aGVHD as compared to controls. Similarly, the absolute number of 'total' gamma/delta+ and V delta 2+ cells was also significantly increased in patients with aGVHD. TCR gamma/delta+ T cells increased as a function of time after BMT reaching a plateau value at about day 60 post-BMT. When patients were stratified for the presence or absence of aGVHD this correlation was maintained only for patients with aGVHD. Finally, most V delta 2+ cells expressed surface T cell activation markers such as CD25 (IL-2 receptor) and DR (MHC class II) antigens. Our results suggest a possible involvement of gamma/delta+ T cells and particularly of V delta 2+ cells in the clinical and immunological events (aGVHD) occurring after allogeneic BMT.

Antigens, Differentiation↗
PubMed1992

Targeting of T or NK lymphocytes against tumor cells by bispecific monoclonal antibodies: role of different triggering molecules.

MAbs directed against triggering surface molecules expressed by T lymphocytes (CD3, TCR, CD2, CD28) or by NK cells (CD2, CD16) are able to induce the functional program of these cells. These MAbs represent suitable reagents to construct biMAbs directed against TAA, in order to specifically target effector lymphocytes against tumor cells. Anti-CD3/anti-EGF-R biMAbs were constructed to specifically direct T lymphocytes against EGF-R+ tumor cells. Such biMAb are able to induce cytolysis of EGF-R+ tumor cell lines (A431, IGROV, KATO-III and U-87) by cytolytic CD3+ effector lymphocytes while tumor cells having low or absent expression of EGF-R were not lysed. In addition, both cytolytic T (CD8+) cells and non-cytolytic (CD4+) IL-2-expanded lymphocytes were able to secrete lymphokines upon contact with EGF-R+ tumor cells. To target NK cells against NK resistant ovarian carcinomas, we used an anti-CD16 Mab (IgG1) together with an anti-ovarian carcinoma MAb (IgG2a), to construct biMAbs using the hybrid hybridoma technique. The hybrid IgG1/IgG2a biMAb triggered the specific lysis of relevant target cells by resting NK cells and by a subset of NK clones. In addition, some TCR gamma/delta+ clones but not TCR alpha/beta+ clones could be targeted by the biMAb.

Antibodies, Monoclonal↗
PubMed1992

Possible targets on carcinoma for bMAb retargeting of lymphocyte or drug cytotoxicity.

Retargeting of drugs or lymphocyte cytotoxicity through bi-specific monoclonal antibodies (bMAbs) has been proven a therapeutic tool against human carcinoma both in pre-clinical in vitro and in vivo studies. Some of these reagents have already been introduced into clinical trials and preliminary results appear to be promising. However, improvement of the specificity of this approach could be achieved by selecting more suitable target molecules on tumor cells. The research focused on developing MAbs directed against molecules with tumor-restricted distribution and homogeneous expression. Cell-membrane receptors for nutrients or growth factors which operationally represent tumor-specific molecules due to their overexpression, could be considered appropriate targets. Several bMAb anti-nutrients (the folate-binding protein) or growth-factor receptor (c-erbB1, c-erbB2)/anti-triggering molecules have been generated and all were able to efficiently retarget the relevant population of lymphocytes on tumor cells. In order to design a more reliable and selective therapeutic tool, the following parameters were analyzed: correlation between cytotoxicity and antigen level, potency and possible modulation of the target molecule.

Antibodies, Monoclonal↗
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

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

Activated CD3- CD16+ natural killer cells express a subset of the lymphokine genes induced in activated alpha beta + and gamma delta + T cells.

In this study we analysed the potential of highly purified polyclonal TcR alpha beta+, TcR gamma delta + and CD3- NK cells, to produce lymphokines in response to mitogenic stimulation. RNA hybridizations were performed to detect with high sensitivity the induction of multiple lymphokine genes. Upon stimulation with lectin and phorbol ester TcR gamma delta + lymphocytes expressed the same set of lymphokine genes as the TcR alpha beta + lymphocytes expressed the same set of lymphokine genes as the TcR alpha beta + lymphocytes, which included IL-2, -3, -4, -5, GM-CSF, TNF alpha and beta, IFN gamma. In contrast, a more limited set of lymphokine genes (GM-CSF, TNF alpha and beta, IFN gamma) was induced in activated CD3- NK cells, thus indicating that this subpopulation of cells may display different regulatory functions, with respect to CD3+ T lymphocytes.

Antigens, Differentiation↗
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↗