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D T Harris

Publications and source records attributed to D T Harris.

At least 55 records · Page 3Linked to original sources
PubMed1992

A function-associated molecule on rat natural killer cells identified by anti-idiotypic monoclonal antibodies.

Monoclonal antibodies were generated against idiotopes on an NK target antigen-specific IgM monoclonal antibody (mab). This mab (18C2) was originally produced against (NC-37) human EBV-transformed B cells. The 18C2 mab inhibits natural killer cell lysis of NC-37 and other target cells by preventing conjugate formation. Anti-18C2(id) mabs were tested for binding to effector cells and screened by ELISA, flow cytometry, and by inhibition of NK cytotoxicity. Two of the anti-18C2(id) (anti-id) mabs (12H1.C5 and 6D9.B11) were chosen for further study. The idiotypic specificity of these anti-id mabs was confirmed by testing their binding to 18C2 hybridoma cells in the presence of homologous and heterologous "cold" inhibitor mabs. Experiments were also conducted to determine the functional properties of these mabs. Anti-18C2(id) mab 12H1.C5 inhibited the cytotoxic activity of rat splenic NK (nylon wool nonadherent cells, NWNA) and rat ALAK cells. Flow cytometric (FCM) analysis of the binding of the anti-18C2(id) mabs demonstrated that mab 12H1.C5 bound 75.43% rat NWNA spleen cells, 43.74% rat ALAK cells, and 74.33% rat CRC- cells. Anti-id mab 6D9.B11 bound 45.20% NWNA cells, 70.45% rat ALAK cells, and 55.86% CRC- cells. Two-color FCM analysis demonstrated that the anti-id mabs not only bound to the same molecule on NK cells, but also these mabs bound to the same molecule as 5C6, an anti-NK cell mab. Biochemical analysis of the antigen recognized by mab 12H1.C5 was determined by Western blotting. The determinant on NWNA cells recognized by mab 12H1.C5 had an M(r) of 40 kDa and appeared to be identical to that recognized by mab 5C6. The same experiment using a transformed rat RNK-16 (CRC-) cell extract and Western blot analysis, demonstrated an M(r) of 42 and 48 kDa in the presence of mabs 5C6 and 12H1.C5. Monoclonal antibody 5C6 was previously shown to recognize a vimentin-like function-associated molecule on NK cell membranes. The anti-id mabs were also shown to have cross-reactivity with the intermediate filament vimentin as determined by Western blot analysis.

Animals↗
PubMed1992

The natural killer cell-like lytic activity expressed by cytolytic T lymphocytes is associated with the expression of a novel function-associated molecule.

Experiments were performed to analyse the natural killer cell (NK)-like cytotoxicity frequently expressed by human antigen-specific cytolytic T lymphocytes (CTL). To this end, several monoclonal antibodies (MoAbs) previously shown to identify a novel function-associated molecule (FAM) involved in human NK function were utilized. Flow cytometry revealed that these MoAbs reacted with the majority of human NK, but only with a subpopulation of CTL isolated from primary mixed lymphocyte cultures. Preincubation of CTL with the MoAbs inhibited the NK-like lysis of K562 targets. Experiments with anti-CD3 MoAb demonstrated that neither the NK-like cytotoxicity of CTL nor the lytic activity of NK were mediated by the CD3 complex. Expression of the novel FAM was found to develop in T-cell cultures at the time that NK-like cytotoxicity was observed. Repeated in vitro antigenic stimulation of CTL was shown to result in loss of NK-like cytotoxicity, as well as loss of the FAM on the CTL surface. Thus, NK-like cytotoxicity displayed by antigen-specific CTL appears to be mediated by a novel FAM that is identical to that structure found on NK.

Adolescent↗
PubMed1991

Identification of an evolutionarily conserved, function-associated molecule on human natural killer cells.

Nonspecific cytotoxic cells (NCC) in teleost fish are analogous to human natural killer (NK) cells and spontaneously lyse a variety of transformed human cell lines sensitive to human NK cell lysis. Monoclonal antibodies (mAbs) made against these NK-like effector cells inhibited their lytic activity. These anti-NCC mAbs were examined with human NK cells for their effects. It was observed that these mAbs bound specifically to a small percentage of peripheral blood lymphocytes (5-15%) and to the majority (greater than 85%) of CD3- NK cells. The mAbs inhibited human NK cell lysis against a variety of transformed cell lines. Single-cell assays showed that the mAbs exerted their effects through inhibition of conjugate formation (recognition). However, the mAbs did not inhibit NK cell-mediated antibody-dependent cell-mediated cytotoxicity. Biochemical analysis of the NK cell molecule revealed that a dimeric structure was involved (distinct from antigen receptors on T cells). Thus, this molecule appears to be a candidate NK cell antigen receptor.

Antibodies, Monoclonal↗
PubMed1990

A monoclonal antibody-purified soluble target cell antigen inhibits nonspecific cytotoxic cell activity.

We have previously reported the characterization of mAb derived against NC-37 target cells. mAb 18C2 and 1E7 inhibit fish cytotoxicity by binding to target cells and thus preventing the formation of conjugates with fish nonspecific cytotoxic cells (NCC). It was therefore presumed that these inhibitory mAb were specific for the target cell Ag necessary for effector cell recognition. mAb 1D4 and 7C6 bind to NC-37 cells but do not inhibit fish cytotoxic activity. We now report the isolation and purification of the Ag recognized by mAb 18C2 (inhibitor) and 1D4 (noninhibitor) by affinity chromatography of solubilized NC-37 target cell extracts. The 18C2-purified soluble target Ag (STAg) caused inhibition of cytotoxicity when preincubated with fish NCC. This inhibitory activity was reversible and dose-dependent ranging from 20 to 70% inhibition with 25 to 100 micrograms 18C2 purified STAg/10(6) NCC. STAg purified by 1D4 affinity chromatography had no effect on fish cytotoxicity. mAb 18C2 and 1E7 preabsorbed with 18C2 STAg lost their inhibitory activity when tested in the fish NCC cytotoxicity assay. Preabsorption of the same mAb with 1D4 STAg had no effect on their activity.

Acetylglucosamine↗
PubMed1990

Pathways of signal transduction in teleost nonspecific cytotoxic cells.

In the present study evidence is presented that both a putative "receptor" binding monoclonal antibody (mAb) and the calcium ionophore A23187, either singly or together, increase receptor expression and lysis of IM-9 target cells by catfish NCC. NCC activity against IM-9 target cells was increased 55% after 1 h mAb treatment. Receptor expression determined by flow cytometry increased 95% following 18-h treatment. A23187 treatment of NCC produced greater than 200% increases in receptor expression. Combined treatments of NCC with 10(-4) M A23187 and 10(-7) M PMA however augmented receptor expression only 22% above that produced by A23187 alone. MAb and A23187 comodulated cytotoxicity by a 65% increase over ionophore treatment alone. MAb and 10(-10) M PMA comodulation produced only 10.6% increases in cytotoxicity compared to mAb. These data demonstrate that the moiety on NCC recognized by 5C6 may provide an activation signal for increased cytotoxicity and receptor expression. Calcium ionophore, either singly or together with mAb, provided an even stronger activation signal for increased lysis and receptor expression.

Animals↗
PubMed1990

Effects of phorbol esters and calcium ionophore on nonspecific cytotoxic cells.

In the present study mechanisms of signal transduction were investigated by treatment of NCC with phorbol esters and calcium ionophore. NCC were stimulated to produce 3-fold increased cytotoxicity by 10(-4) to 10(-5) M A23187. PMA, PDD, and 4-beta phorbol either suppressed NCC lysis (PMA) or had no enhancing effects (PDD and 4-beta). At a concentration of 10(-4) M increased cytotoxicity occurred after 0.5 to 3 hours treatment. Four-hour preincubation enhanced cytotoxicity at suboptimal A23187 concentrations. A23187 produced increased NCC activity at each E:T ratio tested, however, greatest differences in A23187 concentrations were observed at 20:1 and 40:1. The effects of simultaneous treatment of NCC and/or sequential with PMA and A23187 indicated that different transduction pathways might operate to augment cytotoxicity. PMA, 10(-8) M, combined with 10(-4) M concentrations of A23187 produced a 164.7% increase in cytotoxicity compared to media controls, and a 37.7% increase compared to A23187 controls. These data indicate that teleost cytotoxic cells, unlike mammalian NK, are augmentable by increased levels of extracellular calcium without the presence of any other comodulating signals.

Animals↗
PubMed1990

Characterization of normal human lung lymphocytes and interleukin-2-induced lung T cell lines.

Lymphocytes from the lower respiratory tract were obtained by bronchoalveolar lavage of healthy, non-smoking individuals. Various monoclonal antibodies characterizing activated T cells, helper-inducer and suppressor-inducer T cell subsets, and naive versus memory cells were used to define the phenotype of these lymphocytes. The highly variable CD4/CD8 ratio (0.3 to 6.6; mean = 2.1) and the large proportion of the T cells expressing HLA-DR (9 to 38%; mean = 21%) suggested that the T cells were recently activated by antigens selectively stimulating either helper or cytotoxic/suppressor T cell function. Indeed, the CD45RA antigen, a marker characteristic of suppressor-inducer T cells when coexpressed with CD4, and naive T cells in general, was absent from T cells in most preparations (0 to 17%; mean = 5%), while the CD45RO antigen, a marker of memory cells and immature thymocytes, was present on 68 to 100% of all lung T cells. The majority (greater than 70%) of the CD4+ helper T cells was CD45RO+ CD45RA-, a phenotype found on T cells that provide help for B cell immunoglobulin synthesis. Lung T cells proliferated poorly in response to phytohemagglutinin and concanavalin A but did respond to activation with low concentrations of anti-CD3 mAb (2 to 25 ng/ml) and to interleukin-2 (IL-2) alone to similar extent as did autologous peripheral blood lymphocytes.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Detection of function-associated molecules on rat leukemic NK cells: activation by monoclonal antibody or phorbol ester.

In the present study a rat leukemia NK cell line designated CRC- (derived from RNK-16 cells) was shown to spontaneously transform into a noncytolytic (NL) line referred to as CRC-/NL cells. CRC- and CRC-/NL cells were utilized to study pathways of NK activation by phorbol esters, calcium ionophore (A23187), and monoclonal antibody (mAb). 10(-6)-10(-7) M phorbol myristate acetate (PMA) but not phorbol didecanoate or 4-beta-phorbol activated CRC-/NL to lyse YAC-1 targets. Activated CRC-/NL cells produced 20-90% specific cytotoxicity compared to 0-5% for nonactivated cells. 10(-7) M PMA inhibited normal CRC- cytotoxicity. The optimum concentration of PMA for activation was 10(-6)-10(-7) M and 3-6 h treatment time. Augmentation of cytotoxicity by PMA occurred at different E:T ratios. The time required to reverse the PMA activation of CRC-/NL cells was approximately 9-10 h posttreatment. In an effort to attempt to differentiate pathways which initiated activation, CRC-/NL cells were treated with FAM binding mAb, or with combinations of mAb and ionophore, mAb and PMA, or PMA and A23187. mAb singly or in combination with 10(-7) M PMA increased cytotoxicity. However, A23187 either singly or when combined with PMA or mAb did not produce an augmented lysis of YAC-1 target cells. Additional experiments were conducted to determine if PMA activation was associated with FAM binding. This was accomplished by analyzing redirected killing of various FAM mAb-producing myeloma cells in the presence of 10(-7) M PMA. PMA treatment of the CRC-/NL cells caused a significant increase in the lysis of myeloma/mAb-producing cells compared to control cells. Further evidence that FAM binding was associated with cytotoxicity was presented by demonstrating specific inhibition of redirected lysis by homologous mAb. Phenotype analysis of CRC- and CRC-/NL cells demonstrated that OX-7 and OX-1 expression on CRC-/NL cells was increased by 71.8 and 86.8% respectively compared to CRC-. FAM expression (78-83% positives) by CRC- and CRC-/NL cells was not different. These experiments indicated at the functional level that rat NK cells can be activated for increased cytotoxicity by FAM-specific mAb binding and/or by treatment with the diacylglycerol analogue PMA. This implies that protein kinase C mobilization either singly or in concert with inositol-1,4,5-trisphosphate activation following FAM mAb binding may play important roles in NK cell cytotoxicity.

Animals↗
PubMed1989

Induction of activation antigens on human natural killer cells mediated through the Fc-gamma receptor.

NK cells, defined here as lymphocytes bearing the CD16 Ag found on the NK cell Fc-gamma receptor (FcR), are known to enter a proliferative and activated state in response to stimulation with IL-2 as assessed by clonal expansion, short-term DNA synthesis, and de novo expression of lymphocyte-associated activation Ag. We have found that the FcR of NK cells acts as a signaling pathway through which IL-2-dependent activation may be greatly enhanced, allowing for more rapid induction of activation Ag and recruitment of an increased percentage of cells expressing surface markers of cellular activation. FcR-interactive agents, such as solid phase immobilized immune complexes or cross-linked CD16-specific mAb, work synergistically with rIL-2 to elicit a rapid expression of IL2R and transferrin receptors on greater than 50% of purified NK cells as early as day 3 of culture. IL-2 or FcR-interactive stimuli alone were weak or ineffective stimulators by comparison. In contrast to the induction of de novo activation Ag, DNA synthesis was elicited by IL-2 alone, but was not substantially or consistently enhanced by the subsequent addition of FcR-interactive stimuli.

Animals↗
PubMed1989

Identification of a human natural killer cell target cell antigen with monoclonal antibodies.

mAb have been derived against NK cell-sensitive target cells in an effort to identify the target cell structure involved in Ag recognition by NK cells. Several mAb were selected for further study based on their preliminary target cell binding characteristics. Flow cytometry demonstrated that each of these mAb bound to a series of NK-sensitive target cells of various origins (e.g., K562 and Molt-4) while having little or no reactivity with several NK-resistant target cell lines (e.g., SB and Daudi). Functional studies revealed that two of the mAb were able to inhibit the lysis of NK-sensitive K562 target cells by freshly isolated, endogenous NK cells in a dose-dependent fashion. Further, these mAb also could inhibit the killing of K562 target cells by both activated NK cells and cultured lymphokine-activated killer cells, as well as the cytolysis of other NK-sensitive target cells by each of these effector cell populations. Control experiments with another mAb which bound to the target cells but did not inhibit lysis implied that the effects of these mAb on NK cell function was not the result of steric hindrance. Single cell conjugate assays demonstrated that the mAb inhibited NK cell lysis via the inhibition of binding (recognition). Biochemical analysis of this target cell structure revealed that it was a molecule of approximately 42 kDa which may exist as a homodimer in its native state. Thus, it appears that the mAbs identify an unique Ag on the surface of NK cell-sensitive target cells which is involved in NK cell Ag recognition.

Adolescent↗
PubMed1988

Characterization by monoclonal antibodies of a target cell antigen complex recognized by nonspecific cytotoxic cells.

Fish nonspecific cytotoxic cells (NCC)3 recognize and lyse a large variety of human and mouse transformed cells. In an effort to determine the Ag recognized by NCC on these targets, mAb were raised against NC-37 target cells. Four anti-NC-37 mAb were chosen for further characterization based on their effects on NCC lysis of target cells. Purified mAb 18C2 and 1E7 (IgM isotype) inhibited NCC killing of the following targets: U937, MOLT-4, K562, HL-60, DAUDI, NC-37, P815, and YAC-1. The dose-dependent inhibitory activity occurred at the target cell level and ranged from 50 to 70% at a concentration of 50 micrograms/well when compared to noninhibitory mAb 7C6 and 1D4 (IgG isotype). Similarly, mAb 18C2 protected the fish parasite Tetrahymena pyriformis from lysis by NCC when compared to mAb 7C6. Adsorption experiments demonstrated that the inhibitory effect on NC-37 lysis by NCC could be removed in a titratable fashion by incubation of mAb 1E7 with any one of the other target cell lines, but it could not be removed by incubation with effector cells. The inhibitory activity of mAb 1E7 and 18C2 was shown to be caused by the inhibition of conjugate formation between effector and NC-37 target cells. The relative membrane concentration of the antigenic determinants recognized by these mAb on the target cells was studied by flow cytometry using FITC-labeled mAb. These experiments showed that all four mAb bound to the surface of the cells tested. Biochemical analysis with Western blots and immunoprecipitation showed that mAb 18C2 and 1E7 recognize two Ag in NC-37 lysates: a larger protein of around 80 kDa and a smaller one of 42 kDa.

Animals↗
PubMed1988

Identification of a putative antigen receptor on fish nonspecific cytotoxic cells with monoclonal antibodies.

In the present study mAb were derived against flow cytometry (FCM) purified fish (Ictalurus punctatus) nonspecific cytotoxic cells (NCC). mAb 5C6.10.4 and 6D3.2.10 produced 60 to 65% inhibition of lysis of NC-37 target cells (a human B-lymphoblastoid cell line) by unfractionated NCC. mAb 2B2.4.9 and 6D3.4.4 were noninhibitors of cytotoxicity. All mAb were the same isotype (IgM) and were cloned by limiting dilution (2x). Inhibitory activity was specific for the effector cells because the mAb had no effect on NCC cytotoxicity when only the target cells were treated. Inhibition could be produced by preincubation of the mAb with NCC or by no preincubation, and inhibition was not reversible. Killing by FCM-sorted NCC of NC-37 target cells was inhibited almost 100% by mAb 5C6.10.4. Inhibitor mAb also significantly reduced NCC killing of MOLT-4, K562, P815, U937, Daudi, YAC-1, and HL-60 cells. Experiments also were conducted to determine at which stage of the lytic cycle the mAb acted. Both inhibitor mAb significantly inhibited conjugate formation between effector and NC-37 target cells. The technique of FCM was combined with competitive binding experiments to determine that the Ag recognized by both inhibitor and noninhibitor mAb was found on the membranes of the same cells. These results were confirmed by demonstrating (by using FCM) that FITC-labeled inhibitor and biotinylated noninhibitor mAb bound to the same cells. FCM also was next used to determine mAb binding to various effector cell populations. Inhibitor and noninhibitor mAb bound to approximately 25% (5C6.10.4) and 39% (6D3.4.4) of fish anterior kidney cells; to 42% (5C6.10.4) and 54% (6D3.4.4) of fish spleen cells; and to 2.5% (5C6.10.4 and 6D3.4.4) of fish peripheral blood. mAb were used to purify the target cell binding structure found on NCC. Con A-Sepharose purified mAb were used as the fixed ligand for Affi-Gel-10 affinity chromatography experiments. FCM-purified NCC were solubilized and the receptor was purified by using this technique. Analysis of the NCC-purified receptor by 12% SDS-PAGE indicated that the mAb purified structure may be composed of a dimeric molecule consisting of 41 kDa and 38 kDa proteins. The same dimer was purified by using either inhibitory (6D3.2.10) or noninhibitory (6D3.4.4) mAb. Similar results were obtained with immunoprecipitation experiments by using mAb 5C6.10.4. These studies demonstrate that the Ag-binding receptor structure on fish NCC may be comprised of a dimeric complex.

Animals↗
PubMed1988

Molecular mechanisms involved in T cell activation. III. The role of extracellular calcium in antigen-induced lymphokine production and interleukin 2-induced proliferation of cloned cytotoxic T lymphocytes.

The role that extracellular calcium plays in activating resting cloned cytotoxic T lymphocytes (CTL) to proliferate and to produce lymphokines was examined. In these cells, stimulation with interleukin 2 (IL-2) induced a proliferative response without a concomitant production of macrophage-activating factor (MAF), whereas stimulation with antigen or lectin (in the absence of IL-2) induced MAF production but not proliferation. In the case of IL-2-induced proliferation, extracellular calcium was required to initiate proliferation as well as to prevent cellular arrest later in the G2 + M phase of the cell cycle. In MAF production extracellular calcium was required both to activate the phosphatidylinositol signal-transducing mechanism and to mobilize intracellular calcium in antigen- or lectin-stimulated cytotoxic T lymphocytes. Further, extracellular calcium was required for only 8 of the 18 hr of stimulation time which was needed to achieve maximal MAF production, indicating that both calcium-dependent and -independent events exist in the signal pathway. Additional experiments with calcium ionophores and activators of protein kinase C indicated that although both intracellular calcium mobilization and de novo protein phosphorylation are involved in MAF production, an optimal increase in the level of intracellular calcium by itself is insufficient to induce the production of this lymphokine.

Animals↗
PubMed1987

Mechanism of cyclosporin A-induced immunosuppression. Cyclosporin A inhibits receptor-mediated and non-receptor-mediated lymphokine production as well as interleukin-2-induced proliferation in cloned T lymphocytes.

The effects of cyclosporin A (CyA) on the activation processes of cloned murine cytotoxic T lymphocytes (CTL) have been examined. With the use of Day 7 resting cloned CTL it was possible to separate the functions of lymphokine production (macrophage-activating factor, MAF) and interleukin 2 (IL-2)-induced proliferation of these cells. The effect of CyA on each of these activities was analyzed independently. CyA was found to inhibit both receptor-mediated MAF production in response to stimulation with antigen and lectin and MAF production in response to non-receptor-mediated stimulation (by anti-Thy-1 antibodies, ionophore, and phorbol ester). Further, CyA was observed to inhibit the re-entry of these resting CTL into the cell cycle upon stimulation with IL-2. The effect of CyA on MAF production did not appear to be due to inhibition of the signal-transducing mechanism involved in this process (i.e., inositol lipid hydrolysis, calcium mobilization, and protein phosphorylation). The action of CyA on the IL-2-induced proliferation was not due to inhibition of IL-2 receptor expression or the binding of IL-2 to its receptor. Thus, CyA appeared to mediate its suppressive effects on MAF production and IL-2-induced proliferation through an action on some later step(s) in the signal pathways of these activities.

Animals↗
PubMed1987

Inhibition of human natural killer cell activity by a synthetic peptide homologous to a conserved region in the retroviral protein, p15E.

It has been shown previously that the retroviral envelope protein p15E suppresses certain monocyte and lymphocyte functions. In this paper, we describe the effects on natural killer (NK) activity of a synthetic peptide (CKS-17) with homology to a region of p15E conserved among numerous retroviruses. Enriched human NK cells were assayed against K562 tumor target cells in a 51Cr-release cytotoxicity assay. Pretreatment of NK cells with CKS-17 at concentrations as low as 1.5 microM, but not with equivalent concentrations of control materials, markedly and reproducibly suppressed NK lytic activity. Prior exposure of NK cells to interferon-alpha (IFN-alpha) at 1000 U/ml did not alter their sensitivity to CKS-17-induced inhibition. Pretreating NK cells with CKS-17 almost entirely diminished their responsiveness to IFN-alpha and IFN-gamma, but not to interleukin 2 (IL 2). Kinetics experiments demonstrated that CKS-17-mediated suppression of both endogenous and activated NK cells was reversible after 18 hr at 37 degrees C. Experiments designed to examine the CKS-17 mechanism of action revealed that the peptide bound to all Leu-11+ lymphocytes, as shown by two-color flow cytometry. CKS-17 did not, however, inhibit effector cell/target cell conjugate formation. These data suggest a new mechanism for immune suppression mediated by retroviruses; inhibition of NK function. They moreover imply that the CKS-17 peptide interferes with the lytic phase of NK cytolysis.

Adolescent↗
PubMed1987

Molecular mechanisms involved in T cell activation. I. Evidence for independent signal-transducing pathways in lymphokine production vs proliferation in cloned cytotoxic T lymphocytes.

It is well-established that activated T cells proliferate in response to interleukin 2 (IL 2) and produce various soluble lymphokines such as macrophage-activating factor (MAF) in response to antigen. Prior to investigating the molecular events involved in signaling the initiation of these responses in cloned murine cytotoxic T lymphocytes (CTL), we determined whether these responses could occur independently, and we established for each response the time during which signal transducing mechanisms may function. It was found that this cloned CTL population was in a resting state (G1 phase of cell cycle) 7 days after stimulation with antigen plus IL 2. At this time, the incubation of these resting CTL with IL 2 for 4 to 6 hr resulted in a maximal proliferative response that was not accompanied by the production of MAF. Conversely, the incubation of resting CTL with antigen or lectin (in the absence of IL 2) for at least 8 hr resulted in the maximal production of MAF at 24 hr without inducing a proliferative response. In addition, antigen or lectin, but not IL 2, triggered an immediate (less than 1 min) and sustained (at least 8 hr) mobilization of intracellular calcium. The kinetics of this calcium response paralleled the minimum time (8 hr) that was required for resting CTL to interact with either antigen or lectin in order to produce maximal titers of MAF. These results indicate that proliferation and lymphokine (MAF) production in cloned murine CTL are independent events. In these resting CTL, the signal mechanisms that mediate the production of lymphokines are most likely restricted to the initial 8 hr of stimulation by antigen or lectin and involve the rapid and prolonged mobilization of cytoplasmic calcium. Proliferative signals, however, are probably complete within 4 to 6 hr after stimulation by IL 2 and do not involve readily demonstrable fluxes of cytoplasmic calcium, as determined by the fluorescent calcium probe Quin 2.

Animals↗