Immunopathogenic role of TH1 cells in autoimmune diabetes: Evidence from a T1 and T2 doubly transgenic non-obese diabetic mouse model

To improve the feasibility of in vivo monitoring of autoreactive T cells in the diabetogenic process, we generated T1 and T2 doubly transgenic non-obese diabetic (NOD) mice in which transgenic human CD90 (hCD90) is simultaneously expressed on IFN-gamma-producing cells or murine CD90.1 (mCD90.1) is expressed on IL-4-producing cells. These transgenic NOD mice develop diabetes with the same kinetics and incidence as wild type NOD mice, permitting the physiological characterization of CD4(+)hCD90(+) cells, which represent T(H)1 cells in lymphoid organs and at the site of insulitis. CD4(+)hCD90(+) cells had a higher capacity to secret IFN-gamma than CD4(+)hCD90(-) cells in an autoantigen-specific manner. Transgenic mice treated with GAD65 plasmid were protected from autoimmune diabetes, and had a lower number of CD4(+)hCD90(+) cells, confirming the pathogenic role of CD4(+)hCD90(+) cells in autoimmune diabetes. To further investigate the effect of IL-12 on the development of T(H)1 cells in autoimmune diabetes, we crossed these doubly transgenic mice to IL-12p35-deficient NOD mice. Despite severe disturbance of diabetes in p35(-/-) mice, the frequency of T(H)1 cells in these mice was slightly lower than in wild type mice. These data support the pathological role of IL-12 in autoimmune diabetes and suggest the existence an IL-12-independent pathway of T(H)1 development.

The combined effect of IL-4 and IL-10 suppresses the generation of, but does not change the polarity of, type-1 T cells in Histoplasma infection

Dominant type-1 cytokine production is induced in a murine model of systemic histoplasmosis. We used this model to investigate whether the presence of antagonistic cytokines during T cell priming changes the polarity of T cells in response to Histoplasma infection. Before infection with Histoplasma capsulatum, mice were injected twice with goat anti-mouse IgD antiserum (GalphaMdelta), which induced expression of dominant type-2 cytokines. At days 7 and 14 after infection, the GalphaMdelta-treated mice had suppressed IFN-gamma response and a significantly greater fungal burden in their spleens and lungs. The number of IFN-gamma-producing cells as well as the level of IFN-gamma produced per cell was greatly reduced. Not only CD4+ T cells but also CD8+ T cells were affected. The number of Histoplasma-induced IFN-gamma-producing cells was partially restored in GalphaMdelta-treated IL-4-/- and IL-10-/- mice and completely restored in IL-4-/- IL-10-/- mice. Thus, the combined effect of IL-4 and IL-10 suppressed the generation of IFN-gamma-producing cells. A longitudinal study demonstrated that as IL-4 and IL-10 decreased, the number of Histoplasma-induced IFN-gamma-producing cells rapidly increased, and fungal clearance improved, demonstrating that the presence of IL-4 and IL-10 did not permanently change the polarity of T cells.

Cytotoxic T lymphocytes generated by short-term in vitro TCR stimulation in the presence of IL-4 are therapeutically effective against B16 melanoma

P14 TCR transgenic CD8+ T cells (LCMV gp33-specific) were activated by antigen in the presence of either IL-2 or IL-2 + IL-4 to generate effector cytotoxic T lymphocytes (CTLs). The therapeutic effectiveness of such IL-2- or IL-2 + IL-4-grown CTLs was tested in mice that had received intravenous inoculations of B16.gp33 melanoma cells 7 days previously. Administration of P14 CTLs activated by antigen + IL-2 + IL-4 was significantly more effective at reducing melanoma colony formation in the lung than those grown in the presence of antigen + IL-2. Highly significant improvement in survival was observed with 80% of B16.gp33-inoculated mice showing long-term survival after therapy with 10 x 10(6) antigen + IL-2 + IL-4-activated P14 CTLs. Similar therapeutic effectiveness of antigen + IL-2 + IL-4-activated P14 CTLs against subcutaneously inoculated B16.gp33 melanoma cells was also found. There was significant reduction in P14 CD8+ T cells in the peripheral blood of B16.gp33-inoculated mice than in mice that did not receive B16.gp33 melanoma cells, indicating possible homing of P14 CD8+ T cells to the site of tumor growth or antigen-induced apoptotic cell death. These results may have implications in tumor therapy using CTLs grown ex vivo, especially during early stages of tumor formation. They also support the concept that the therapeutic effectiveness of CTLs can be governed by the cytokine context in which they are activated.

Anti-CD95-induced lethality requires radioresistant Fcgamma RII+ cells. A novel mechanism for fulminant hepatic failure

The Jo2 anti-mouse CD95 monoclonal antibody induces lethality in mice characterized by hepatocyte death and liver hemorrhage. Mice bearing a defect in Fas expression or in the Fas-mediated apoptotic pathway are resistant to Jo2. Here we show that FcgammaRII knockout mice or mice with monoclonal antibody-blocked FcgammaRII are also resistant to Jo2. The critical FcgammaRII(+) cells are radioresistant and could not be reconstituted with splenic cells. Death of sinusoidal lining cells and destruction of sinusoids were observed, consistent with the characteristic liver hemorrhage and the selective FcgammaRII expression in sinusoidal lining cells but not hepatocytes. Hemorrhage developed coincident with hepatocyte death and the sharp rise of serum alanine aminotransferase and alanine aminotransferase. Invariably, moribund mice showed severe liver hemorrhage and destruction of sinusoids. The data demonstrate a novel mechanism by which the destruction of liver sinusoids, induced by the Jo2-mediated co-engagement of Fas and FcgammaRII, leads to severe hemorrhage and lethal fulminant hepatitis.

The roles of interleukin-1 and interleukin-1 receptor antagonist in antigen-specific immune responses

Despite evidence that interleukin (IL)-1 promotes the proliferation of some T helper 2 (Th2) cell clones in vitro, the physiological role of IL-1 in the regulation of antigen-specific immune responses remains undefined. Using a liposome-DNA delivery system, we transiently expressed IL-1 receptor antagonist (IL-1Ra) to suppress IL-1 functions at the site of the antigen-specific primary immune response. Our data indicate, for the first time, that IL-1Ra downregulates antigen-specific IL-4 and IgE responses, with concomitant enhancement of interferon-gamma and IgG2a responses in vivo. In addition, IL-1 can promote Th2 development in an IL-4-independent manner in vitro. Thus, the balance between endogenous IL-1 and IL-1Ra during the primary immune response can be an important factor in determining the antigen-specific effector function of T cells.

An activating mutation in the gamma1 subunit of the AMP-activated protein kinase

The AMP-activated protein kinase (AMPK) is a heterotrimeric protein composed of a catalytic alpha subunit and two regulatory subunits, beta and gamma. The gamma subunit is essential for enzyme activity by virtue of its binding to the C-terminus of the alpha subunit and appears to play some role in the determination of AMP sensitivity. We demonstrate that a gamma1R70Q mutation causes a marked increase in AMPK activity and renders it largely AMP-independent. This activation is associated with increased phosphorylation of the alpha subunit activation loop T172. These in vitro characteristics of AMPK are also reflected in increased intracellular phosphorylation of one of its major substrates, acetyl-CoA carboxylase. These data illustrate the importance of the gamma1 subunit in the regulation of AMPK and its modulation by AMP.

Induction of CD8 T cells by vaccination with recombinant adenovirus expressing human papillomavirus type 16 E5 gene reduces tumor growth

The potential of the E5 protein as a tumor vaccine candidate has not been explored yet. In this study, we evaluate the human papillomavirus type 16 (HPV-16) E5 protein delivered by an adenovirus vector as a tumor vaccine for cervical lesions. The results demonstrate that a single intramuscular injection of a recombinant adenovirus carrying the HPV-16 E5 gene into syngeneic animals can reduce the growth of tumors which contain E5 gene expression. Moreover, the E5 vaccine-induced tumor protection occurs through CD8 T cells but not through CD4 T cells in in vitro assays. In addition, our studies using knockout mice with distinct T-cell deficiencies confirm that cytotoxic T-lymphocyte-induced tumor protection is CD8 dependent but CD4 independent. Hence, HPV-16 E5 can be regarded as a tumor rejection antigen.

Potent induction of long-term CD8+ T cell memory by short-term IL-4 exposure during T cell receptor stimulation

An important goal of vaccination is to achieve long-term survival of functional memory T cells. Using a MHC-compatible adoptive transfer system, we show here that a short, 3-day IL-4 but not IL-2 or IL-12 exposure during in vitro T cell receptor stimulation of naive CD8(+) T cells induced long-lasting in vivo memory. Such long-term memory CD8(+) T cells expressed antigen-specific cytotoxicity and the potential for IFN-gamma and IL-4 production. Our results support the concept that functional T cell longevity can be regulated by cytokines during initial antigen encounter and provide a rational foundation for vaccine development. They also may have implications in formulating optimal therapeutic regimens of ex vivo expanded autologous cancer- and HIV-specific CD8(+) T cells. In addition, the availability of large numbers of memory CD8(+) T cells generated through our high-efficiency system should facilitate progress in the molecular dissection of CD8(+) T cell memory development.

Recombinant adeno-associated virus expressing human papillomavirus type 16 E7 peptide DNA fused with heat shock protein DNA as a potential vaccine for cervical cancer

In this study, we explore a potential vaccine for human papillomavirus (HPV)-induced tumors, using heat shock protein as an adjuvant, a peptide vaccine for safety, and adeno-associated virus (AAV) as a gene delivery vector. The tumor vaccine was devised by constructing a chimeric gene which contained HPV type 16 E7 cytotoxic T-lymphocyte (CTL) epitope DNA (M. C. Feltkamp, H. L. Smits, M. P. Vierboom, R. P. Minnaar, B. M. de Jongh, J. W. Drijfhout, J. ter Schegget, C. J. Melief, and W. M. Kast, Eur. J. Immunol. 23:2242-2249, 1993) fused with the heat shock protein gene as a tumor vaccine delivered via AAV. Our results demonstrate that this vaccine can eliminate tumor cells in syngeneic animals and induce CD4- and CD8-dependent CTL activity in vitro. Moreover, studies with knockout mice with distinct T-cell deficiencies confirm that CTL-induced tumor protection is CD4 and CD8 dependent. Taken together, the evidence indicates that this chimeric gene delivered by AAV has potential as a cervical cancer vaccine.

Recent developments in CD8+ T-lymphocyte memory research

Appropriately activated CD8+ T cells differentiate into cytotoxic effectors capable of eliminating cancer cells and virally infected cells. Successful generation and maintenance of effective CD8+ T-cell memory, through either natural infection or through vaccination, establishes long-term protection against various pathogenic agents and, therefore, contributes significantly to our health. This report is a review of recent advances in CD8+ T-cell memory research. The pool of memory CD8+ T cells is maintained through a mechanism of rapid turnover that is antigen-independent, class I major histocompatibility complex (MHC I) antigen-dependent, and, potentially, IL-15-dependent. Memory CD8+ T cells, in marked contrast to naive CD8+ T cells, constitutively express cytotoxic effector function in the absence of antigen stimulation. Furthermore, the vast majority of activated CD8+ T cells in mice infected with lymphocytic choriomeningitis virus are antigen-specific, prompting revision of the commonly held view that many antigen-nonspecific CD8+ T cells are activated in response to viral infection. These newly published results not only provide exciting insights into the inner workings of CD8+ memory maintenance, but they also establish a sound foundation for future investigation. As more detailed molecular and cellular mechanisms of the regulation of memory CD8+ T-cell survival emerge, the most exciting challenge will be to apply this understanding toward the rational design of vaccines and immunotherapies. These potentials are even more relevant in view of the critical nature of CD8+ T cells in combating viral infection and cancer, and the relative paucity of effective drugs against these diseases.

Age-Associated Rapid and Stat6-Independent IL-4 Production by NK1−CD4+8− Thymus T Lymphocytes

The source of IL-4 required for priming naive T cells into IL-4-secreting effectors has not been clearly identified. Here we show that upon TCR stimulation, thymus NK1−CD4+8− T cells produced IL-4, the magnitude of which was inversely correlated with age. This IL-4 production response by Th2-prone BALB/c mice was ∼9-fold that of Th1-prone C57BL/10 mice. More than 90% of activated NK1−CD4+8− thymocytes did not use the invariant Vα14-Jα281 chain characteristic of typical CD1-restricted NK1+CD4+ T cells. Stat6-null NK1−CD4+8− thymocytes produced bioactive IL-4, with induction of IL-4 mRNA expression within 1 h of stimulation. Our results support the possibility that TCR repertoire-diverse conventional NK1−CD4+ T cells are a potential IL-4 source for directing naive T cells toward Th2/type 2 CD8+ T cell (Tc2) effector development.

Age-associated rapid and Stat6-independent IL-4 production by NK1-CD4+8- thymus T lymphocytes

The source of IL-4 required for priming naive T cells into IL-4-secreting effectors has not been clearly identified. Here we show that upon TCR stimulation, thymus NK1-CD4+8- T cells produced IL-4, the magnitude of which was inversely correlated with age. This IL-4 production response by Th2-prone BALB/c mice was approximately 9-fold that of Th1-prone C57BL/10 mice. More than 90% of activated NK1-CD4+8- thymocytes did not use the invariant V alpha 14-J alpha 281 chain characteristic of typical CD1-restricted NK1+CD4+ T cells. Stat6-null NK1-CD4+8- thymocytes produced bioactive IL-4, with induction of IL-4 mRNA expression within 1 h of stimulation. Our results support the possibility that TCR repertoire-diverse conventional NK1-CD4+ T cells are a potential IL-4 source for directing naive T cells toward Th2/type 2 CD8+ T cell (Tc2) effector development.

Lymphokine regulation of activation-induced apoptosis in T cells of IL-2 and IL-2R beta knockout mice

Recent studies using IL-2R alpha knockout mice have generated conflicting results regarding the hypothesis that IL-2/IL-2R interaction is obligatory for the development of AICD, which plays a central and pivotal role in maintaining peripheral tolerance. A relevant consequence of AICD defect is the demonstrated development of autoimmune lymphoproliferative disease in IL-2, IL-2R alpha, and IL-2R beta knockout mice, but not in IL-4, IL-7, or IL-7R knockout mice. Whether IL-4, IL-7, or IL-15 can provide the required signal for AICD development is addressed here using IL-2 and IL-2R beta knockout mice. Lymph node T cells from knockout mice were stimulated with Con A plus rIL-1 for 3 days and then maintained in high concentrations of rIL-4, rIL-7, or rIL-15 for an additional 3 days before they were subjected to AICD analysis. Our study demonstrates that IL-4, IL-7, and IL-15 can transduce signals critical for AICD development in the absence of IL-2-mediated signals. The requirement for relatively high concentrations of these lymphokines suggests their limited role in maintaining peripheral T cell tolerance, thus explaining the differential expression of autoimmune lymphoproliferative disease in the targeted mutant strains described above.

Retinoblastoma gene deficiency has mitogenic but not tumorigenic effects on erythropoiesis

The retinoblastoma protein (Rb), an important ubiquitous cell cycle regulator, was initially identified as the retinoblastoma tumor suppressor. To further address the activities of Rb in proliferation and tumorigenesis in the hematopoietic lineage, we transplanted Rb-/- fetal liver cells into sibling mice and assessed the outcome of Rb-/- hematopoietic cells in both short-term and long-term studies. Rb-/- hematopoietic cells rescued lethally irradiated mice with an efficiency comparable to that of wild-type cells. In spleen colony-forming unit assays, proliferation rates of the Rb-/- cells were greater than those of the wild-type cells. Similarly, in vitro burst-forming unit-erythroid and colony-forming unit-erythroid assays showed increased erythroid colony numbers from Rb-/- embryonic livers. Recipients of Rb-/- cells lived for more than 15-18 months, and most blood cell lineages matured normally with the expected switch from fetal to adult hemoglobin. However, the continued presence of nucleated erythrocytes in the peripheral blood and extensive extramedullary erythropoiesis indicated that the Rb-/- erythrocytes were not completely normal. No erythroleukemia developed during the 15-18 month period following transplantation. These results demonstrate the mitogenic effect but not tumorigenic transformation in erythrocyte lineage in the absence of Rb, which is distinct from the effect of Rb deficiency in neuroectodermal cells. The study supports the prevalent model that loss of the ubiquitously expressed tumor suppressor gene predisposes to only a limited spectrum of tumors.

Deficient CD4+ T cell proliferation in the class 1 MHC-restricted 2C TCR-transgenic mouse

A comparative study of immune function and marker expression of CD4+ T cells from MHC class 1-restricted 2C TCR-transgenic (2C+) and control transgene-negative littermate (2C-) mice was performed. While 2C+CD4+ T cells resembled memory T cells on the basis of CD44highCD45RBlow expression, the majority of 2C-CD4+ T cells were of the CD44lowCD45RBhigh naive phenotype. Slightly lower levels of TCR-beta and CD3 were found on 2C+CD4+ T cell than 2C-CD4+ T cells. Vigorous proliferation by 2C-CD4+ T cells was observed upon stimulation with 1) anti-CD3 mAb presented through the FcR of macrophages; 2) immobilized (plate-bound) anti-CD3 + anti-CD28 mAbs; and 3) PMA + ionomycin. In marked contrast, all three mitogenic stimuli stimulated highly deficient proliferative responses by 2C+CD4+ T cells. However, significant IL-2 production was detected both in anti-CD3 and in PMA + ionomycin-stimulated cultures of 2C+CD4+ T cells. While intracellular calcium in 2C-CD4+ T cells rapidly increased following anti-CD3 addition, no such increase was observed for similarly stimulated 2C+CD4+ T cells. Anti-CD28, PMA, and coculture with 2C-CD4+ T cells each failed to significantly correct the deficient 2C+CD4+ T cells proliferation as induced by anti-CD3. In addition, IL-2, IL-4, and IL-7 supplements also failed to reverse the deficient proliferation of 2C+CD4+ T cells despite expression of IL-2R component alpha-, beta-chains and the gamma-chain common also to IL-4R and IL-7R. Thymus CD4+8- T cells from the 2C-transgenic mouse were similarly deficient in proliferation as spleen CD4+ T cells. A small subpopulation of CD4+ T cell from the 2C-transgenic mouse expressed the transgenic TCR alpha:beta heterodimer as detected by the 1B2 anti-2C clonotypic mAb; both 1B2+ and 1B2- subpopulations proliferated poorly in response to anti-CD3 and to PMA + ionomycin. These results raise the possibility that TCR engagement with MHC class 1 molecules during early intrathymic development can result in the emergence of CD4+ T cells characterized by unusual marker expression and function.

Deficient CD4+ T cell proliferation in the class 1 MHC-restricted 2C TCR-transgenic mouse

A comparative study of immune function and marker expression of CD4+ T cells from MHC class 1-restricted 2C TCR-transgenic (2C+) and control transgene-negative littermate (2C-) mice was performed. While 2C+CD4+ T cells resembled memory T cells on the basis of CD44highCD45RBlow expression, the majority of 2C-CD4+ T cells were of the CD44lowCD45RBhigh naive phenotype. Slightly lower levels of TCR-beta and CD3 were found on 2C+CD4+ T cell than 2C-CD4+ T cells. Vigorous proliferation by 2C-CD4+ T cells was observed upon stimulation with 1) anti-CD3 mAb presented through the FcR of macrophages; 2) immobilized (plate-bound) anti-CD3 + anti-CD28 mAbs; and 3) PMA + ionomycin. In marked contrast, all three mitogenic stimuli stimulated highly deficient proliferative responses by 2C+CD4+ T cells. However, significant IL-2 production was detected both in anti-CD3 and in PMA + ionomycin-stimulated cultures of 2C+CD4+ T cells. While intracellular calcium in 2C-CD4+ T cells rapidly increased following anti-CD3 addition, no such increase was observed for similarly stimulated 2C+CD4+ T cells. Anti-CD28, PMA, and coculture with 2C-CD4+ T cells each failed to significantly correct the deficient 2C+CD4+ T cells proliferation as induced by anti-CD3. In addition, IL-2, IL-4, and IL-7 supplements also failed to reverse the deficient proliferation of 2C+CD4+ T cells despite expression of IL-2R component alpha-, beta-chains and the gamma-chain common also to IL-4R and IL-7R. Thymus CD4+8- T cells from the 2C-transgenic mouse were similarly deficient in proliferation as spleen CD4+ T cells. A small subpopulation of CD4+ T cell from the 2C-transgenic mouse expressed the transgenic TCR alpha:beta heterodimer as detected by the 1B2 anti-2C clonotypic mAb; both 1B2+ and 1B2- subpopulations proliferated poorly in response to anti-CD3 and to PMA + ionomycin. These results raise the possibility that TCR engagement with MHC class 1 molecules during early intrathymic development can result in the emergence of CD4+ T cells characterized by unusual marker expression and function.

Host responses in patients with generalized refractory periodontitis

Although patients with refractory periodontitis have been widely reported, no clear biologic profile of these patients has been noted. The purpose of the present study was to evaluate host responsiveness of a well-defined group of refractory periodontitis patients by determining the effect of a lipopolysaccharide (LPS) challenge on monocyte surface receptor density and on the release of inflammatory mediators. Venous blood was obtained from 7 refractory periodontitis, 8 stable periodontal maintenance, and 8 gingivitis patients with no evidence of periodontitis. Mononuclear cells were cultured in either control media or media treated with Actinobacillus actinomycetemcomitans (Aa), Porphyromonas gingivalis (Pg), or Salmonella typhimurium (S. typh) LPS. At 0 and 24 hours supernatants were assayed for prostaglandin-E2 (PGE2) and interleukin-1 beta (Il-1 beta) release by ELISA. Using flow cytometry the density of specific monocyte surface receptors were assayed with Mo3e and LeuM3 monoclonal antibodies (mAb); T-cell CD4/CD8 ratios were assayed with OKT-3, OKT-4, and OKT-8 mAb. After 24 hours incubation with Pg or S. typh LPS, the upregulation of the Mo3e receptor was significantly decreased for refractory periodontitis patients (P < 0.05) when compared to gingivitis and to stable maintenance patients. In refractory periodontitis patients the T-cell CD4/CD8 ratio was decreased. Upon stimulation with Pg or S. typh LPS, monocytes from stable maintenance and refractory periodontitis patients released more Il-1 beta (P < 0.05) and PGE2 (P = 0.13 and 0.15) than monocytes from gingivitis subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Mitogen-induced IL-2 production and proliferation at defined stages of T helper cell development

Th cell development inside the thymus can be defined on the basis of qualitative and quantitative CD4 and CD8 marker expression and follows the pathway of CD4-8- cells----CD4+8+ cells----CD4+8low cells----CD4+8- cells, which presumably emigrate to seed the periphery and serve as functionally mature Th cells. The various cell subpopulations at defined developmental stages were isolated by electronic cell sorting and examined for mitogen induced IL-2 production and cell proliferation responses. For TCR-alpha beta-bearing CD4+8+ and CD4+8low thymocytes that are actively engaged in positive and negative selection processes, negligible to low levels of IL-2 production and cell proliferation were observed in response to TCR:CD3 triggering or to the combined activation of protein kinase C and calcium mobilization mediated by PMA and ionomycin, respectively. For CD4-8- TCR-alpha beta early thymocytes that have not yet entered the selection process, PMA + ionomycin induced significant cell proliferation but little IL-2 production, in the absence of added IL-1. However, addition of IL-1 caused a powerful induction of IL-2 production that was accompanied by increased cell proliferation. Triggering of the TCR:CD3 complex had no effect on CD4-8-TCR(-)-alpha beta thymocytes as they do not express detectable levels of TCR-alpha beta. For thymus CD4+8- Th cells, the first cells that have completed TCR repertoire selection, vigorous proliferation was observed in response to TCR:CD3 triggering in the presence of added IL-2. However, the development of IL-2 responsiveness was not accompanied by high level IL-2 inducibility as TCR:CD3 triggering caused only marginal IL-2 production. In contrast, spleen CD4+8- T cells, the most "mature" representatives of Th cells, expressed high levels of IL-2 production as well as IL-2 responsiveness in response to TCR:CD3-mediated stimulation. The lack of anti-TCR-induced IL-2 production by thymus CD4+8- T cells was not due to an intrinsic defect as high levels of IL-2 production was induced by PMA + ionomycin. Possible reasons for the temporal acquisition and differential control of IL-2 inducibility and IL-2 responsiveness are discussed in the context of established Th cell development pathway.

Induction of high level IL-2 production in CD4+8- T helper lymphocytes requires post-thymic development

Triggering of the CD3:TCR complex by optimal concentrations of anti-CD3, anti-TCR beta-chain, and allogeneic stimulator cells induced dramatically higher levels (fivefold for anti-CD3, greater than 10-fold for anti-TCR beta-chain, 84-fold for alloantigen) of IL-2 production in spleen CD4+8- T cells than their thymic counterparts, despite comparable levels of CD3 and TCR beta-chain expression. The nature of the reduced IL-2 production was examined by analysis of anti-CD3-induced IL-2 production at the single cell level. The frequency of IL-2-producing cells in spleen CD4+8- T cells (40.0%) was approximately threefold that of thymus CD4+8- T cells (14.5%). Furthermore, the average IL-2 levels among positive IL-2 producers was also approximately threefold higher in spleen CD4+8- T cells than their thymic counterparts. Adoptive transfer of purified Thy-1.2+ CD4+8- T cells into Thy-1.1-congenic hosts provided a physiologic and histocompatible system that enabled identification of transferred donor (Thy-1.2+) among a sea of host (Thy-1.2-) CD4+ T cells, whose immune function with respect to IL-2 inducibility was examined after isolation by electronic cell sorting. Donor CD4+ T cells thus isolated from host spleen shortly (1 day) after i.v. transfer of thymus CD4+8- T cells were similar to freshly isolated thymus CD4+8- T cells in that they both produced little IL-2 in response to anti-CD3. However, by day 3 post-transfer, IL-2 production by donor CD4+8- T cells had more than doubled and by day 8, they produced IL-2 levels comparable to those of host spleen CD4+8- T cells. A similar acquisition of high level IL-2 inducibility in thymus CD4+8- T cells upon i.v. transfer into Thy-1.1-congenic hosts was also observed using allogeneic cells as the stimulus of IL-2 production. When thymus CD4+8- T cells were intra-thymically transferred into Thy-1.1-congenic hosts, those donor cells that emigrated to the periphery became high IL-2 producers in a time-dependent manner, whereas those that remained inside the thymus showed no signs of up-regulation in IL-2 inducibility. Intrathymic transfer of CD4-8- thymocytes revealed that the most recent thymic emigrant CD4+8- T cells contained few IL-2-producing cells and were not functionally mature with respect to high level IL-2 inducibility.

Mitogen-induced IL-2 production and proliferation at defined stages of T helper cell development

Th cell development inside the thymus can be defined on the basis of qualitative and quantitative CD4 and CD8 marker expression and follows the pathway of CD4-8- cells----CD4+8+ cells----CD4+8low cells----CD4+8- cells, which presumably emigrate to seed the periphery and serve as functionally mature Th cells. The various cell subpopulations at defined developmental stages were isolated by electronic cell sorting and examined for mitogen induced IL-2 production and cell proliferation responses. For TCR-alpha beta-bearing CD4+8+ and CD4+8low thymocytes that are actively engaged in positive and negative selection processes, negligible to low levels of IL-2 production and cell proliferation were observed in response to TCR:CD3 triggering or to the combined activation of protein kinase C and calcium mobilization mediated by PMA and ionomycin, respectively. For CD4-8- TCR-alpha beta early thymocytes that have not yet entered the selection process, PMA + ionomycin induced significant cell proliferation but little IL-2 production, in the absence of added IL-1. However, addition of IL-1 caused a powerful induction of IL-2 production that was accompanied by increased cell proliferation. Triggering of the TCR:CD3 complex had no effect on CD4-8-TCR(-)-alpha beta thymocytes as they do not express detectable levels of TCR-alpha beta. For thymus CD4+8- Th cells, the first cells that have completed TCR repertoire selection, vigorous proliferation was observed in response to TCR:CD3 triggering in the presence of added IL-2. However, the development of IL-2 responsiveness was not accompanied by high level IL-2 inducibility as TCR:CD3 triggering caused only marginal IL-2 production. In contrast, spleen CD4+8- T cells, the most "mature" representatives of Th cells, expressed high levels of IL-2 production as well as IL-2 responsiveness in response to TCR:CD3-mediated stimulation. The lack of anti-TCR-induced IL-2 production by thymus CD4+8- T cells was not due to an intrinsic defect as high levels of IL-2 production was induced by PMA + ionomycin. Possible reasons for the temporal acquisition and differential control of IL-2 inducibility and IL-2 responsiveness are discussed in the context of established Th cell development pathway.

Induction of high level IL-2 production in CD4+8- T helper lymphocytes requires post-thymic development

Triggering of the CD3:TCR complex by optimal concentrations of anti-CD3, anti-TCR beta-chain, and allogeneic stimulator cells induced dramatically higher levels (fivefold for anti-CD3, greater than 10-fold for anti-TCR beta-chain, 84-fold for alloantigen) of IL-2 production in spleen CD4+8- T cells than their thymic counterparts, despite comparable levels of CD3 and TCR beta-chain expression. The nature of the reduced IL-2 production was examined by analysis of anti-CD3-induced IL-2 production at the single cell level. The frequency of IL-2-producing cells in spleen CD4+8- T cells (40.0%) was approximately threefold that of thymus CD4+8- T cells (14.5%). Furthermore, the average IL-2 levels among positive IL-2 producers was also approximately threefold higher in spleen CD4+8- T cells than their thymic counterparts. Adoptive transfer of purified Thy-1.2+ CD4+8- T cells into Thy-1.1-congenic hosts provided a physiologic and histocompatible system that enabled identification of transferred donor (Thy-1.2+) among a sea of host (Thy-1.2-) CD4+ T cells, whose immune function with respect to IL-2 inducibility was examined after isolation by electronic cell sorting. Donor CD4+ T cells thus isolated from host spleen shortly (1 day) after i.v. transfer of thymus CD4+8- T cells were similar to freshly isolated thymus CD4+8- T cells in that they both produced little IL-2 in response to anti-CD3. However, by day 3 post-transfer, IL-2 production by donor CD4+8- T cells had more than doubled and by day 8, they produced IL-2 levels comparable to those of host spleen CD4+8- T cells. A similar acquisition of high level IL-2 inducibility in thymus CD4+8- T cells upon i.v. transfer into Thy-1.1-congenic hosts was also observed using allogeneic cells as the stimulus of IL-2 production. When thymus CD4+8- T cells were intra-thymically transferred into Thy-1.1-congenic hosts, those donor cells that emigrated to the periphery became high IL-2 producers in a time-dependent manner, whereas those that remained inside the thymus showed no signs of up-regulation in IL-2 inducibility. Intrathymic transfer of CD4-8- thymocytes revealed that the most recent thymic emigrant CD4+8- T cells contained few IL-2-producing cells and were not functionally mature with respect to high level IL-2 inducibility.

Subpopulations of CD8+ cytotoxic T cell precursors collaborate in the absence of conventional CD4+ helper T cells

Four different subpopulations (Ly6Cneg, Ly6Clow, Ly6Cint, and Ly6Chi) of CD8+ T cells were arbitrarily defined on the basis of differential expression of Ly6C Ag. By combining the processes of electronic cell sorting and automated cell deposition, small numbers of respective CD8+ T cell subpopulations were directly deposited into tissue culture wells in which mitogen-stimulated responses were studied. Anti-CD3-stimulated proliferation and IL-2 production were the strongest by Ly6Cneg/Ly6Clow T cells, moderate for Ly6Cint T cells, and highly deficient for Ly6Chi T cells. The level of IL-2 production for Ly6Cneg CD8+ T cells was comparable to that of conventional CD4+ Th cells. Allogeneic stimulator cells elicited a strong cytotoxic response by Ly6Cneg + low but not Ly6Chi CD8+ T cells in the absence of added lymphokines. When IL-2 was supplied in excess, anti-CD3 induced comparable levels of cell proliferation and cytotoxic activity in Ly6Cneg, Ly6Clow, Ly6Cint, and Ly6Chi CD8+ T cells whereas alloantigen stimulated an approximate fivefold higher cytotoxic response by Ly6Chi than Ly6Cneg + low CD8+ T cells. Stimulation of co-cultures of B10 (CD8b) Ly6Cneg + low and congenic B10.CD8a Ly6Chi CD8+ T cells in the absence of added lymphokines, followed by selective elimination of activated CD8.1+ (CD8.2+) T cells by anti-CD8.1 (anti-CD8.2) + C treatment, allowed the demonstration that help provided by Ly6Cneg + low T cells can be effectively used by both Ly6Cneg + low and Ly6Chi T cells in anti-CD3 and alloantigen induced proliferative and cytotoxic responses, respectively.

Subpopulations of CD8+ cytotoxic T cell precursors collaborate in the absence of conventional CD4+ helper T cells

Four different subpopulations (Ly6Cneg, Ly6Clow, Ly6Cint, and Ly6Chi) of CD8+ T cells were arbitrarily defined on the basis of differential expression of Ly6C Ag. By combining the processes of electronic cell sorting and automated cell deposition, small numbers of respective CD8+ T cell subpopulations were directly deposited into tissue culture wells in which mitogen-stimulated responses were studied. Anti-CD3-stimulated proliferation and IL-2 production were the strongest by Ly6Cneg/Ly6Clow T cells, moderate for Ly6Cint T cells, and highly deficient for Ly6Chi T cells. The level of IL-2 production for Ly6Cneg CD8+ T cells was comparable to that of conventional CD4+ Th cells. Allogeneic stimulator cells elicited a strong cytotoxic response by Ly6Cneg + low but not Ly6Chi CD8+ T cells in the absence of added lymphokines. When IL-2 was supplied in excess, anti-CD3 induced comparable levels of cell proliferation and cytotoxic activity in Ly6Cneg, Ly6Clow, Ly6Cint, and Ly6Chi CD8+ T cells whereas alloantigen stimulated an approximate fivefold higher cytotoxic response by Ly6Chi than Ly6Cneg + low CD8+ T cells. Stimulation of co-cultures of B10 (CD8b) Ly6Cneg + low and congenic B10.CD8a Ly6Chi CD8+ T cells in the absence of added lymphokines, followed by selective elimination of activated CD8.1+ (CD8.2+) T cells by anti-CD8.1 (anti-CD8.2) + C treatment, allowed the demonstration that help provided by Ly6Cneg + low T cells can be effectively used by both Ly6Cneg + low and Ly6Chi T cells in anti-CD3 and alloantigen induced proliferative and cytotoxic responses, respectively.

Private hospitals in public health systems

Heterogeneity of cancer stem/progenitor cells that give rise to different forms of cancer has been well demonstrated for leukemia. However, this fundamental concept has yet to be established for solid tumors including breast cancer. In this communication, we analyzed solid tumor cancer stem cell markers in human breast cancer cell lines and primary specimens using flow cytometry. The stem/progenitor cell properties of different marker expressing-cell populations were further assessed by in vitro soft agar colony formation assay and the ability to form tumors in NOD/SCID mice. We found that the expression of stem cell markers varied greatly among breast cancer cell lines. In MDA-MB-231 cells, PROCR and ESA, instead of the widely used breast cancer stem cell markers CD44⁺/CD24^-/low and ALDH, could be used to highly enrich cancer stem/progenitor cell populations which exhibited the ability to self renew and divide asymmetrically. Furthermore, the PROCR⁺/ESA⁺ cells expressed epithelial-mesenchymal transition markers. PROCR could also be used to enrich cells with colony forming ability from MB-361 cells. Moreover, consistent with the marker profiling using cell lines, the expression of stem cell markers differed greatly among primary tumors. There was an association between metastasis status and a high prevalence of certain markers including CD44⁺/CD24^−/low, ESA⁺, CD133⁺, CXCR4⁺ and PROCR⁺ in primary tumor cells. Taken together, these results suggest that similar to leukemia, several stem/progenitor cell-like subpopulations can exist in breast cancer.