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The most prominent immunological abnormalities in the aged were reduced immune response against foreign antigens and increased auto-antibody production against intrinsic antigen. To explain these immunological abnormalities, we examined the various functions of human lymphocytes from aged and young groups at cellular, molecular and genetic levels. The results indicate: The first, T cells from the aged showed significantly reduced proliferative response not only to specific antigen TAP but also to mitogen PHA or combined stimulation of PMA and ionomycin. The second, the number of IL-2 receptor, particularly high affinity ones, on aged T cells were significantly reduced in the aged after TAP and PHA stimulation. The third, the ability to express Tac (p55) and p70/75 of IL-2R and to internalize the rIL-2 bound to the receptor were reduced in aged T cells. The fourth, although the ability to proliferate in response to SAC stimulation was two folds less in the aged B cells than that in the young ones, the capacity to differentiate into IgG and IgA class ISC after the combined stimulation with SAC and partially purified BCDF were rather increased on the basis of the number of viable cells recovered. The fifth, the amount of IL-2 activity produced by aged T cells was ten fold less than that by young ones, but the amount of BCDF activity produced by aged T cells was three folds higher than that by young ones after PHA stimulation. An inverse correlation between IL-2 activity and BCDF activity was found when the both activities were determined in the same sample.(ABSTRACT TRUNCATED AT 250 WORDS)

1. Proliferative responses to the costimulation with phorbol-12-myristate-13-acetate (PMA) and suboptimal doses of ionomycin in the purified T and B cells from old mice were lower than those from young mice. 2. The degree of the age-related decline was more significant in T cells than in B cells. 3. Taurine, a sulfur containing amino acid, augmented the proliferative responses of T cells from both young and old mice. 4. The augmentation of the proliferative response by taurine was more marked in old T cells than in young T cells. 5. The concentration of intracellular free calcium ion ([Ca2+]i) was significantly lower in old T cells when stimulated with PMA and ionomycin than observed in young T cells. 6. In the presence of taurine, the concentration of [Ca2+]i in the old T cells significantly increased under stimulation by PMA and ionomycin. 7. The results indicate that taurine improved the proliferative response in old T cells by restoration of the increment of the concentration of [Ca2+]i under the stimulation by PMA and ionomycin.

In a previous paper, we have demonstrated that Neurotropin, a non-protein extract isolated from the inflamed skin of rabbits inoculated with vaccinia virus, restores decreasing immune responses through the recovery of interleukin-2 (IL-2) production in aging BALB/c mice. To clarify the mechanism by which Neurotropin restores IL-2 production, its effect on the recruitment of IL-2-producing T-cells from bone marrow cells was examined using syngenic radiation bone marrow chimeras. Two fundamental lesions in recruiting IL-2-producing T-cells in aging BALB/c mice were demonstrated: (1) a drastic decline of the maturation of bone marrow cells to IL-2-producing T-cells as demonstrated by old----young chimeras; and (2) an environment unable to support bone marrow cell differentiation to IL-2-producing T-cells by young----old chimeras. Neurotropin clearly restored the maturation of bone marrow cells to IL-2-producing T-cells when administered from 13 to 16 month-old mice, whereas the non-complementing environment was not normalized with Neurotropin administration. These results suggest that Neurotropin administration restores IL-2 production through the recovery of the maturation of bone marrow cells to IL-2-producing T-cells, resulting in restoration of in vivo T-cell immune response in aging BALB/c mice.

The proportion of CD8 positive cells in the peripheral blood AET-rosette forming T cells from aged persons was significantly reduced than that from young persons. The difference in the proportion between aged and young groups became more significant after proliferative response to a mitogen phytohemagglutinin (PHA) or a specific antigen tuberculin active peptide (TAP). The purified macrophage-deprived T cells (Twp), CD4 (T4) positive cells or CD8 positive cells were prepared from aged or young persons. These cell preparations lost proliferative response to PHA or TAP but showed marked proliferative response to the combined stimulation to 1 microM of ionomycin and 1 nM of phorbol-12-myristate-13-acetate (PMA) at usual culture cell density (2.5 X 10(5)/ml). Proliferative responses of these cell preparations to the combined stimulation were significantly reduced in the aged than those in the young and the magnitude of the difference in the proliferative responses between aged and young groups was more pronounced in CD8 positive cell population than in CD4 positive cell population. Although the cell preparations were relatively independent of exogenous IL-2 for the proliferative response to the combined stimulation of ionomycin and PMA at usual culture cell density, they needed exogenous IL-2 for sustained proliferation at lower culture cell density (5 X 10(3)/ml). These IL-2-dependent proliferative responses to the combined stimulation in the aged were significantly lower than those in the young and again the difference in the proliferative magnitude between aged and young groups was greater in CD8 positive population. The mechanism(s) of age-related change of the proportion and proliferative ability of T subsets were discussed.

In this report, we examined whether novel interleukin 2 (IL-2) binding molecules (p70/75) are responsible for signal transduction and internalization of IL-2 in T cells by using a monoclonal antibody H-31 to Tac antigens. We found that H-31 inhibited the binding of IL-2 to Tac antigens but not novel IL-2 binding molecules. Scatchard plot analysis revealed that in the presence of H-31, intermediate affinity sites (Kd = 1 to 1.5 nM) were detectable and the number of them was similar to that of high affinity IL-2 receptor (IL-2R) (Kd = 10 to 15 pM) in the absence of H-31. Furthermore, the kinetics of endocytosis of IL-2 via p70/75 showed the same pattern as via high affinity IL-2R. Finally, high doses of IL-2 (100 to 10,000 U/ml) are required for the proliferation of T cells in the presence of H-31, whereas in the absence of H-31, physiologic doses of IL-2 (1 to 100 U/ml) induced the proliferation. These results taken together suggest that novel IL-2 binding molecules are related to signal transduction of IL-2 and that Tac antigens are essential for constructing of high affinity IL-2R, although Tac antigens may not be responsible for signal transduction.

In the present paper we demonstrate that there is an antigenic determinant common to two different types of human leukaemia-associated antigens, i.e. human thymus leukaemia-associated (HTL) antigens and common acute lymphoblastic leukaemia (cALL) antigen. In addition, there are distinct antigenic determinants which are unique to the HTL antigens or to the cALL antigen. The new, common antigenic determinant will be useful as a new differentiation marker of human haematopoietic cells as well as a new leukaemia-associated marker. In the present study, we used several different anti-human leukaemia antisera which include those prepared by immunizing rabbits (Nos. 7549 and 7550) with purified HTL antigens. The antisera 7549 and 7550, without any absorption, showed strong specificity as well as strong antibody activity toward leukaemia cells. These are the first anti-human leukaemia antisera, except for the monoclonal hybridoma antibodies, that show good specificity for leukaemia cells without prior absorption.

To examine the immunopharmacological actions of an extract isolated from inflamed skin of rabbits inoculated with Vaccinia virus (Neurotropin), its effect on the immune responses in aging BALB/c mice was examined. Neurotropin clearly restored the decreasing T-cell-dependent immune responses such as delayed-type hypersensitivity (DTH) response and plaque-forming cells (PFC) response to sheep red blood cells (SRBC) when administered i.p. from 13 months old (mo) to 16 mo. However, Neurotropin administration from 2 to 5 mo had no effect on the immune responses of young animals. Neurotropin administration from 13 to 16 mo restored not only the T-cell proliferation of spleen cells induced by concanavalin A (Con A) and phytohemagglutinin (PHA), but also the interleukin-2 (IL-2) production by spleen cells activated with Con A. However, Neurotropin did not affect the responsiveness of Con A-activated spleen cells to exogenous recombinant IL-2. An absence of suppressor cells capable of inhibiting the IL-2 production in the spleens was confirmed in the 16 mo mice. Neurotropin administration also restored IL-1 production by peritoneal macrophages stimulated with lipopolysaccharide (LPS). These results suggest that long-term administration of Neurotropin restores the decreasing T-cell-dependent immune responses through the recovery of IL-2 and in part IL-1 production, but not the responsiveness to IL-2 in aging BALB/c mice.

Persistent diabetes mellitus with marked hyperglycemia was induced in mice by the administration of streptozotocin. In these streptozotocin-induced diabetic mice, resistance to tubercle bacillus challenge and primary as well as secondardy humoral immune responses against foreign erythrocytes were markedly depressed. The T-cell function in delayed hypersensitivity to 2,4-dinitro-1-fluorobenzene and bacterial phagocytic activity or peritoneal macrophages were markedly depressed. In contrast, the B-cell function in antibody production against T-independent antigen and the intracellular killing of bacteria in peritoneal macrophages were intact. We concluded that depression of the T-cell function or the phagocytic activity of macrophages or both may be the main immunological defect in these mice.

Previous work from our laboratory demonstrated the mitogenic response of human peripheral blood T lymphocytes by phytohemagglutinin (PHA), phorbol myristate acetate (PMA) and ionomycin, or interleukin 2 (IL-2). Increasing levels of incorporated 5-azacytosine inhibited the action of the methyltransferase suggesting that incorporation of 5-azacytosine into DNA could be responsible for the inhibiting effect of 5-azacytidine (5-aza-CR) on DNA methylation. In this study, we first demonstrated the inhibition of mitogenic response by agents, such as PHA, PMA and ionomycin, or IL-2, that activate or augment activation of human peripheral blood T cells by treatment of the analog 5-azacytidine. Over 1 microM of 5-azacytidine, we detected significant inhibition of proliferative response and over 5 microM of 5-azacytidine toxic effect of cell viability. We found no significant change of T cell subsets after treatment of 5-azacytidine.

Proliferative response of T cells from aged persons was significantly reduced to a specific antigen tuberculin-active peptide (TAP) determined by [3H]TdR uptake and FCM in comparison to that from the young. Cytokinetic analysis for the proliferative response to TAP showed that, in the aged, the clonal size or the number of the first generation responding cells to TAP was not significantly reduced but the ability to repeat replication was more profoundly affected. Neither the delayed entry into the cell replication nor prolongation of the cell cycle time could explain these results. Similar results have been reported on the proliferative response of T cells to mitogen: PHA (Phytohemagglutinin). Expression of Tac-antigen on T cells determined by anti-Tac antibody binding with FACS after stimulation with either TAP or PHA was found to be reduced significantly in the aged. Both the numbers of high and low affinity IL-2 receptors determined by radiolabelled IL-2 binding assay were also reduced in the aged, but the degree of reduction in number of high affinity ones was more pronounced than that in low affinity ones. Tac-positive T cells were isolated with the use of anti-Tac rosette methods and stimulated with recombinant IL-2 (r-IL-2). Their proliferative response was significantly lower in the aged than that in the young at any concentration of r-IL-2 examined. The number of the first generation responding cells to r-IL-2 in purified Tac-positive T cells from the aged was 82% of that from the young whereas the proliferative response by aged T cells was 39% of that by young ones when the cells were allowed to repeat replication for 3 days. The mechanisms of these multifactorial defects in proliferation of T cells from aged persons were discussed.

The age-associated changes of the expression of IL-2 binding molecules p55/Tac(alpha chain) and p70/75(beta chain) were examined after phytohemagglutinin (PHA) stimulation. The expressions of both p55/Tac molecules and p70/75 molecules were significantly reduced in the aged compared with those in the young persons. The amounts of p55/Tac and p70/75 molecules on T cells from the aged were 55% and 59% of those on young ones, respectively. The ratio of the amount of p70/75 to that of p55/Tac in aged T cells was 0.28 and that in young ones was 0.26. The ratio was somewhat higher in the aged but not significantly. We also examined the kinetics of IL-2 internalization mediated by its receptor. The calculated t1/2 of receptor-mediated IL-2 internalization was 17 min in the aged and 16 min in the young, respectively. There was no kinetic difference between the 2 groups. The percentage of the internalized IL-2 to the sum total was 58.2% in the aged and 73.4% in the young (P less than 0.02). the amount of internalized IL-2 in T cells from the aged was 48.6% of that from the young (P less than 0.01).

Using radiolabeled interleukin-2 (IL-2), affinity cross-linking and binding assays revealed that the expression of intermediate-affinity IL-2 binding molecules (p70/75) on freshly prepared T cells from patients with systemic lupus erythematosus (SLE) was significantly decreased in comparison with that in normal subjects. The proliferative response of T cells to high doses of IL-2 was also reduced in patients with SLE. The decreased expression of p70/75 reflects the hyporesponsiveness to IL-2 of T cells in patients with SLE.

We generated a monoclonal antibody, termed SN2, which defines a human T cell leukemia-associated cell surface glycoprotein, GP37, with an approximate m.w. of 37,000. This antibody was generated by using a human leukemia antigen preparation. The reactivity and specificity of SN2 were characterized by a sensitive radioimmunoassay against a variety of cultured and uncultured human cells. In selected cases, the cell specimens were tested further by indirect immunofluorescence staining. Among the various cultured malignant and nonmalignant human cell lines tested, SN2 reacted only with leukemic T cell lines, with one exception. It reacted with 10 of 11 leukemic T cell lines tested; the 10 reactive cell lines are PEER, JM, MOLT-4, CCRF-CEM, CCRF-H-SB2, RPMI 8402, DND-41, HPB-ALL, SKW-3, and HPB-MLT; the unreactive line was HUT 78. The reactive cell lines were derived from patients either with T cell-type acute lymphoblastic leukemia (the first eight cell lines), with T cell chronic lymphocytic leukemia (SKW-3), or with Japanese adult T cell leukemia-lymphoma (HPB-MLT). The unreactive cell line, HUT 78, was from a patient with Sezary syndrome. Results consistent with the above were obtained from studies in which uncultured malignant cell specimens from different cancer patients were tested against SN2; SN2 reacted only with T leukemia cells. Among various uncultured normal cell specimens tested, SN2 did not react with thymocytes, bone marrow cells, peripheral blood lymphocytes containing B and T cells, purified T cells, monocytes, granulocytes, or erythrocytes. It did, however, react with platelets.

The abilities of highly purified B cells to repeat replication for clonal expansion and to differentiate into immunoglobulin secreting cells (ISC) were examined in the aged and young groups. B cells from the aged showed twofold less proliferative response to B cell mitogen Cowan 1 (SAC) than those from the young. The original clone size of SAC responding B cells determined by colchicine block and [3H] thymidine [( 3H] TdR) uptake was not significantly reduced in the aged whereas the ability to repeat replication to expand clonal size was significantly reduced. B cells from aged and young persons were induced into ISC by combined stimulation with SAC and partially purified B cell differentiation factor (BCDF) free of IL-2 activity. ISCs for IgG and IgA were rather increased or at least not reduced in number in the aged as compared with those in the young. We also determined the IL-2 and BCDF activity produced by T cells from aged and young persons. Upon PHA stimulation, the aged T cells produced tenfold less IL-2 activity and threefold higher BCDF activity than did young T cells. Approximately threefold increase in spontaneous secretion of BCDF activity by aged T cells was found as compared with young T cells. The inverse correlation between the IL-2 activity and BCDF activity was found when both activities were determined in the same samples.

Murine monoclonal hybridoma antibodies were generated efficiently by using a human leukemia antigen preparation which was isolated from the cell membranes of MOLT-4 (a T-leukemia cell line) by means of a novel system. The generated monoclonal hybridoma antibodies were screened and characterized by a radioimmunoassay using a variety of cell specimens as targets. The results showed that the antigen(s) defined by several of these monoclonal hybridoma antibodies is associated with human T-cell leukemia and further suggest that this antigen(s) is a new type of human leukemia-associated cell surface antigen.

Proliferative responses of highly purified T and B cells from aged persons to the combined stimulation with ionomycin and PMA were more significantly reduced than that from young ones although the degree of the age-related reduction was more significant in T cells than in B cells. In B cells, the levels and kinetics of c-myc gene expression after the stimulation were comparable between aged and young groups. In T cells, the maximum level of c-myc gene expression after the stimulation was comparable between the two age groups but the rate of reduction of c-myc mRNA was significantly retarded in the aged. The results of nuclear run on transcription assay showed the reduction of the rate of c-myc mRNA degradation seemed to be the cause. The levels and kinetics of c-myb gene expression in either T or B cells were comparable between the two age groups. We further examined the level of methylation of Xho I site of c-myc gene. The level of the methylation was significantly lower in the aged T cells and more significant in aged CD 8 positive T cells although that in aged B cells was comparable to that in young ones. The relation between a reduced proliferation, a retarded rate of c-myc mRNA degradation and reduction of methylation level of c-myc gene was discussed.

We have generated and characterized a hybridoma monoclonal antibody, termed SN1, that defines a unique human T-cell leukemia antigen. This antibody was generated by using a human leukemia antigen preparation isolated from cell membranes of MOLT-4, a leukemia T-cell line derived from a patient with T-cell-type acute lymphoblastic leukemia (T-ALL). SN1 was characterized by a sensitive microscale radioimmunoassay using a variety of cultured and uncultured human cells. In selected cases, the cell specimens were further tested by immunoperoxidase staining and an immunofluorescence staining test. The results of the radioimmunoassay were in agreement with those of the two other tests. Among the various cultured malignant and nonmalignant cell lines, SN1 reacted only with leukemia T-cell lines derived from patients with T-ALL; it reacted with all six T-ALL cell lines tested-i.e., JM, CCRF-CEM, CCRF-H-SB2, RPMI 8402, PEER, and MOLT-4. In the case of uncultured cell specimens derived from cancer patients, SN1 reacted with four of four cases of T-ALL but did not react with specimens derived from 41 patients with other types of cancer. SN1 did not react with any normal human cell specimens tested, both cultured and uncultured. These specimens include normal lymphoblastoid cell lines, thymocytes, bone marrow cells, spleen cells, lymph node cells, peripheral blood mononuclear cells, lymphocytes containing B and T cells, purified T cells, monocytes, granulocytes, erythrocytes, and platelets. Furthermore, SN1 did not react with phytohemagglutinin-activated T cells nor with concanavalin A-activated T cells. The results show that monoclonal antibody SN1 defines a type of human leukemia antigen that is expressed on the cell surface of T-cell-type ALL cells. The results further show the usefulness of SN1 in the diagnosis of cancer patients and suggest its therapeutic potential. We designate this antigen TALLA, a T-cell ALL antigen.

We examined the nature of cytoplasmic signal transduction pathways in cord blood T cells by stimulating them with tumor promoter (TPA) and calcium ionophore (A23187). Costimulation of T cells with TPA and A23187 induced optimal proliferative responses on Day 2 in cord T cells but on Day 4 in adult T cells. The maximal responses observed in cord T cells were much less than those of adult T cells, whereas the Con A-induced proliferative responses of these cells showed no significant differences. The reduced responses of cord T cells were due to their lower efficiency in activating the cellular events in T cell activation and proliferation phase, because cord T cells have significantly less ability than adult T cells to express IL-2 receptor as well as HLA-DR and produce IL-2 molecules, thereby inducing proliferation. These data show immature characteristics of intracellular signal transduction pathways in cord T cells, which are directly related with the functional immaturity of cord T cells.