Junko Shima

Significant increase in plasma immunoreactive atrial natriuretic polypeptide concentration during head-out water immersion

To investigate the physiological regulatory mechanism of human atrial natriuretic polypeptide (hANP) secretion, plasma hANP was measured by a direct radioimmunoassay during head-out total body water immersion (WI) in normal men. Five healthy men were immersed in water for 1 hr. Urine volume and Na excretion were significantly increased during WI. Plasma hANP increased significantly during WI peaking at 30 min. and returned toward the baseline after WI. Plasma renin activity and norepinephrine were suppressed occasionally during WI. Plasma ADH did not change throughout the study period. Maximal increments in plasma hANP correllated with that in urine output or urinary Na excretion during WI. These data suggest that acute central hypervolemia caused by WI increases hANP secretion and that this increase may participate in the diuretic response to WI.

Immune dysfunction expressed selectively on L3T4+ T cells in the tumor-bearing state.

Spleen cells from normal C3H/He or BALB/c mice generate cytotoxic T‐lymphocyte (CTL) responses to both trinitrophenyl (TNP)‐modified syngeneic cells (TNP‐self) and allogeneic cells. In contrast, cells from these strains of mice bearing a syngeneic tumor failed to induce anti‐TNP‐self‐CTL responses, although portions of the same responding cells generated comparable anti‐allo‐CTL responses to those induced by normal responding cells. Although anti‐allo‐CTL responses were inducible from only Lyt‐2+ T‐cell subset of responding cells from normal or tumor‐bearing mice, induction of TNP‐CTL responses required the participation of L3T4+ T‐cell subset as well as Lyt‐2+ CTL precursors. In addition, the fact that the addition of concanavalin A‐stimulated culture supernatant to cultures of responding cells from tumor‐bearing mice resulted in the induction of appreciable anti‐TNP‐self CTL responses demonstrated the defect of L3T4+ T‐cell function in the tumor‐bearing state. Such a functional defect was ascribed neither to the loss of L3T4+ T cells nor to the generation of suppressor cells in spleen cells of tumor‐bearing mice. It was found on one hand that in vitro stimulation of antigen‐presenting cell (APC)‐depleted normal responding population with TNP‐self prepared from cells of normal or tumor‐bearing mice produced comparable anti‐TNP CTL responses. On the other hand, APC‐depleted responding cells from tumor‐bearing mice were unable to induce anti‐TNP CTL responses under conditions in which APC‐depleted normal responding cells induced an effective TNP‐CTL response. These results indicate that selective impairment of L3T4+ T cell‐mediated immunity is induced in the tumor‐bearing state and that such an impairment is ascribed to the dysfunction of L3T4+ T cells themselves, but not of APC required for the activation of L3T4+ T‐cell subset.

Mediation of in vivo Tumor‐neutralizing Activity by Lyt‐2+ as Well as L3T4+ T Cell Subsets

The present study reexamines the cell surface nature of T cells mediating in vivo protective tumor immunity with the use of anti‐L3T4 and ‐Lyt‐2 antibodies. C3H/HeN mice hyperimmune against syngeneic MH134 hepatoma or MCH‐1‐A1 fibrosarcoma were prepared by intradermal (id) inoculation of viable tumor cells followed by surgical resection of the tumor and by repeated challenges with viable tumor cells. Spleen cells from these mice were fractionated into L3T4+ or Lyt‐2+ T cell subset by treatment with anti‐Lyt‐2 or ‐L3T4 antibody plus complement (C). Winn assays performed by utilizing such fractionated T cells have revealed that both L3T4+ and Lyt‐2+ T cell subsets from hyperimmune mice produced complete tumor protection. Flow microfluorometry study illustrated that the treatment with anti‐L3T4 or ‐Lyt‐2 antibody plus C resulted in the complete isolation of L3T4− Lyt‐2+ (Lyt‐2+) or L3T4+ Lyt‐2− (L3T4+) T cell subset, respectively. This contrasted with the failure of treatment with anti‐Lyt‐1 antibody plus C to isolate all T cells expressing Lyt‐2 marker. It was further demonstrated that each subset of T cells exerted its anti‐tumor effect in a tumor‐specific way and without a requirement for the other alternative subpopulation of unprimed T cells. These results indicate that Lyt‐2+ T cell subset can be successfully isolated by treatment with anti‐L3T4 but not with anti‐Lyt‐I antibody plus C, and that each single subset of Lyt‐2+ and L3T4+ T cells can function as in vivo effector T cells.

The augmentation of tumor-specific immunity using haptenic muramyl dipeptide (MDP) derivatives. III. Eradication of disseminated murine chronic leukemia cells by utilizing MDP hapten-reactive helper T-cell activity.

SummaryA previous paper has demonstrated that enhanced tumor-specific immunity could be induced by priming mice with Bacillus Calmette Guerin (BCG) and subsequently immunizing them with syngeneic tumor cells modified with BCG-cross-reactive muramyl dipeptide (MDP) hapten [15]. The present study establishes a tumorspecific immunotherapy protocol for a murine chronic leukemia based on the above T-T cell collaboration between antitumor effector T cells and anti-MDP hapten helper T cells induced by BCG priming. BALB/c mice which had been primed to BCG were injected intravenously (i.v.) with viable, syngeneic BCL1 leukemia cells. One week later, these mice were immunized intraperitoneally (i.p.) with unmodified or MDP hapten-modified, 10,000 R X-irradiated BCL1 cells, followed by 4 booster immunizations at 5-day intervals. The administration of unmodified BCL1 tumor cells into BCG-primed mice failed to prevent them from tumor death due to the persistent growth of preinjected BCL1 cells. In contrast, the immunization of BCG-primed, BCL1 leukemia-cell-bearing mice with MDP-modified BCL1 cells resulted in a high growth inhibition of leukemia cells and protection of these mice from death by leukemia. It was also revealed that potent tumorspecific, T-cell-mediated immunity was generated in mice which survived in this immunotherapy model. Thus, these results indicate that administration of MDP hapten-modified, syngeneic leukemia cells into leukemia-bearing mice which have been primed with BCG results in potent tumor-specific, T-cell-mediated immunity attributable to preventing the growth of disseminated leukemic cells.

RENAL INTERACTION OF ATRIAL NATRIURETIC PEPTIDE WITH ANGIOTENSIN II: GLOMERULAR AND TUBULAR EFFECTS

1. The possible interactions between the renal effects of atrial natriuretic peptide (ANP) and angiotensin II (All) were studied in normal sodium‐replete human subjects. Recent investigations have suggested that ANP inhibits the pressor and volume‐retaining effects of activation of the renin‐angiotensin system. Thus, ANP may attenuate the effects of All on renal haemodynamics or tubular transport.

Selective Suppression of the Generation of Anti‐tumor L3T4+ but Not of Lyt‐2+ T Cell‐mediated Immunity in the Tumor‐hearing State

C3H/He mice hyperimmune against syngeneic MH134 hepatoma were prepared by intradermal (id) inoculation of viable tumor cells followed by surgical resection of the tumor and by repeated id challenges with viable tumor cells. Winn assays performed utilizing spleen cells from these mice have revealed that both Lyt‐2+ and L3T4+ T cell subsets from MH134‐hyperimmune mice produced complete tumor protection. The in vivo tumor‐neutralizing activity was also found in spleen cells from tumor‐bearing mice at various times after id implantation of MH134 tumor cells. However, in contrast to comparable tumor‐neutralization by Lyt‐2+ and L3T4+ T subsets from hyperimmune mice, only the Lyt‐2+ T cell subset from tumor‐bearing mice was capable of mediating the in vivo protective immunity. L3T4+ T cell‐mediated immunity was not detectable in the tumor‐bearing state irrespective of the length of the sensitization period with a primary growing tumor, but emerged in the mice which resisted the first tumor challenge after the resection of the primary tumor. These results indicate that the emergence of L3T4+ T cell‐mediated anti‐tumor immunity is stage‐dependent and the Lyt‐2+ T cells represent the main functional subset in the tumor‐bearing state, although both subsets of T cells are potentially capable of effecting anti‐tumor in vivo immunity. The results are discussed in relation to the selective suppression of the L3T4+ but not of Lyt‐2+ T cell function in the tumor‐hearing state.

Changes in the plasma hANP level during long-term salt loading in patients with essential hypertension

Serial changes in the plasma hANP (human atrial natriuretic peptide) level in patients with essential hypertension were determined during high salt intake for two weeks after salt restriction for 5 days. The mean plasma hANP level decreased during salt depletion for 5 days from 60 +/- 10 pg/ml to 39 +/- 8 pg/ml. During high salt intake (20 g NaCl/day) for two weeks, the plasma hANP level increased gradually to a maximum of 71 +/- 16 pg/ml on day 7 and then decreased to 54 +/- 9 pg/ml on day 14. The plasma levels of renin activity, aldosterone and noradrenaline decreased during salt repletion. Changes in the plasma hANP level were correlated positively with those of urinary sodium excretion and negatively with those of plasma renin activity on days 7 and 14 of salt repletion. Change in the plasma hANP level correlated with that in the mean blood pressure on day 14, but not day 7 of salt repletion. These findings indicate that the plasma hANP level is closely related to sodium intake in patients with essential hypertension.

Role of angiotensin II in the renal response to atrial natriuretic peptide in normal subjects.

Summary: Atrial natriuretic peptide (ANP) has been shown to inhibit angiotensin II (Ang II)‐induced steroidogenesis and vasoconstriction. To investigate the role of Ang II in the renal response to ANP, a synthetic ANP (0.1 μg/kg/min, 60 min) was infused for 1 h in eight subjects with or without pretreatment with an inhibitor of the converting enzyme, enalapril (20 mg, p.o.), or Ang II (10 ng/kg/min). ANP infusion alone caused increases in urinary volume, urinary sodium excretion, and glomerular filtration rate (GFR). However, enalapril treatment abolished these diuretic and natriuretic effects of ANP. In this group, GFR was decreased and no tubular effects, which was estimated by urinary excretion of sodium and phosphate, were observed. The antinatriuretic effects of exogenous Ang II were reversed by concomitant ANP infusion, which inhibited both proximal and postproximal sodium reabsorption induced by Ang II without changing the GFR. These results indicate that endogenous Ang II plays an obligatory role in the natriuretic response to ANP and also suggested that ANP inhibits Ang II‐stimulated tubular reabsorption of sodium.

Application of T Cell—T Cell Interaction to Enhanced Tumor-Specific Immunity Capable of Eradicating Tumor Cells in Vivo

Investigations have attempted to delineate the consequences of malignant transformation of cells by the appearance of new cell surface structures [tumor-associated antigens (TAA) or tumor-associated transplantation antigens (TATA)] that could be identified by specific antiserum or by their ability to induce a specific cellular immune response. Considerable efforts have been undertaken to establish the significance of these tumor cell surface structures by correlating their cell surface expression with changes that take place during the course of neoplastic disease. The most compelling evidence for the existence of TATA comes from the study of chemically induced tumors of inbred rodents. These tumors express neoantigens capable of immunizing syngeneic or autochthonous hosts against subsequent challenge with the same tumor.(1–4)