Mixed lymphocyte reaction in mice genetically selected for high (Hi/PHA) or low (Lo/PHA) responsiveness to phytohemagglutinin.

Lymph node cells from Hi/PHA and Lo/PHA mice were evaluated for proliferative response after stimulation by allogeneic lymphocytes (MLR) originating from four inbred strains of different H-2 haplotype (C57B1/6, DBA/2, CBA, A). Reactivity to MLR and PHA were compared in these two lines and in the four inbred strains. The high and low responder status of Hi/PHA and Lo/PHA, as determined by T mitogens lymphocyte responsiveness, was also observed when one measured T responsiveness after MLR. Values obtained with the four inbred strains are included in the range of those measured in Hi/PHA and Lo/PHA cells when stimulated by PHA as well as by allogeneic cells. In contrast, when used as stimulator cells, Hi/PHA or Lo/PHA lymphocytes induce an equivalent proliferative response versus every responder inbred strain studied. These experiments support the hypothesis of a common genetic control of proliferative response following PHA or MLR stimulation. The genes implicated would be different from those coding for I region associated antigens.     

Effect of PHA on lymphocyte respiratory activity in mice

A study of the intensity of oxygen consumption by mice lymphocytes at different stages of cultivation with PHA showed a pronounced increase of the respiratory activity beginning from the 14th hour. Maximum values of oxygen consumption by stimulated cells were observed at the 16th and 30th hours of cultivation (before the beginning of blastogenesis and before the maximum uptake of H3-thymidine, respectively.     

Peripheral lymphocyte response to PHA and T cell population among atomic bomb survivors

The percentage of T lymphocytes of atomic bomb survivors showed no change as a function of age or exposure dose. The percentage of T cells was slightly lower in malignant-tumor patients than in the control group, but was significantly higher in the group with chromosomal aberrations than in the control group. The percentages of phytohemagglutinin (PHA)-induced transformation of peripheral lymphocytes decreased significantly with age in the 0 rad control group and the 200+ rad exposure group, particularly so in the latter. The malignant-tumor group also showed lower percentages of PHA-induced transformation than the control group. The percentages of PHA-induced transformation of lymphocytes of the chromosomal-aberration group were significantly depressed as compared with that of the control group.     

Factors affecting lymphocyte culture for chromosome studies

Factors affecting the transformation of brown trout, Salmo trutta L. , and carp, Cyprinus carpio L. , lymphocytes in culture for subsequent karyotyping are examined. Optimum conditions for mitosis are established in respect of medium, mitogen, atmosphere, buffering system and serum.     

Properties of histamine-induced suppressor factor in the regulation of lymphocyte response to PHA in mice

Splenic T lymphocytes release a suppressor factor into the culture supernatant when incubated for 24 hr with histamine (10^?4M). Histamine-induced suppressor factor (HISF) inhibits lymphocyte response to PHA; it is released by T lymphocytes (either nylon-nonadherent or nylon-adherent lymphocytes) and not by B-cells or macrophages; its production is not observed after depletion of histamine receptor-bearing lymphocytes and is blocked by the H2 receptor antagonist (cimetidine) but not by the H1 receptor antagonist (diphenhydramine). Gel filtration by Sephadex G100 chromatography indicates that HISF had an approximate MW of 45,000 to 68,000. Its inhibitory activity was removed by passage over a histamine RSA-Sepharose column, but not by passage over rabbit anti-mouse Ig-Sepharose column; it was blocked by prostaglandin synthetase inhibitor (PGS) (Ro 205720) indicating that this activity is mediated by a prostaglandin (PG) synthesis.     

Pressor responsiveness to vasopressin in spontaneously hypertensive rats

The present study was designed to find out whether pressor responsiveness to vasopressin (AVP) is altered in spontaneously hypertensive rats (SHR) in comparison with their normotensive controls (WKY). Blood pressure and heart rate changes after injection of graded doses of 2.5, 5.0 and 10.0 ng of AVP (Calbiochem) i.v. were compared in 9 conscious, unrestrained spontaneously hypertensive (SHR) and 11 normotensive Wistar Kyoto (WKY) rats, chronically instrumented with venous and arterial catheters. The threshold dose necessary to elicit a significant increase in blood pressure and reduction of heart rate was lower in WKY than in SHR. At each dose level the blood pressure elevation persisted for a longer period in WKY than in SHR. Bradycardia was greater in WKY than in SHR both in absolute terms and in relation to the blood pressure increase. Thus, the results reveal diminished pressor responsiveness to moderate doses of AVP in SHR in spite of suppressed reflex bradycardia. It is suggested that the peripheral action of AVP on the vascular system is attenuated in SHR.     

Hypothalamic responsiveness to oestrogen in hypothyroid rats.

When 50 iu of PMS is given at 28 days of age, ovulation occurs on day 31, in thyroidectomized rats receiving PMS at 28 days of age, ovulation appears on day 30 and 31. PMS treated thyroidectomized rats were given 0.5 mug oestrogen at 9 a.m. on day 29 or 30. Injection on day 29 increases ovulation, but the injection of day 30 has no effect. Injection of 1.0 mug oestrogen on day 29 reduces activity, however, 1.0 mug on day 30 increases ovulation. These results infer than the hypothyroid state in PMS-treated rats significantly alters hypothalamic responsiveness to oestrogen.     

Anti-idiotypic T lymphocyte responsiveness in murine Schistosomiasis mansoni

Pooled sera from CBA/J mice infected for greater than or equal to 16 weeks with the blood fluke Schistosoma mansoni were immunoaffinity purified using soluble schistosome egg antigens (SEA) coupled to Sepharose 4B. The bound and then eluted fraction was shown to contain only immunoglobulins and to have anti-SEA activity. These anti-SEA antibodies stimulated proliferation of lymph node cells from mice infected with S. mansoni for 8, 12, or greater than or equal to 16 weeks but not from uninfected mice. The cells stimulated by anti-SEA antibodies were nylon wool adherent, Thy-1.2+, L3T4+, Lyt-2-lymphocytes. Immunoglobulins without anti-SEA activity isolated from the sera of syngeneic uninfected mice were not stimulatory for cells from normal or infected animals. Thus the responding T cells appear to be stimulated by the idiotypes expressed on the syngenic anti-SEA antibodies. These data present evidence for anti-idiotypic cellular reactions in murine schistosomiasis that could play important immunoregulatory roles in this disease.     

Effects of aging on cell cooperation and lymphocyte responsiveness to cytokines

Functional activities and cell cooperation of macrophages (Mphi), T cells, and B cells of young and old Lewis rats were compared. Splenic M phi from young and old rats provided accessory help for T cell mitogenesis and B cell mitogenesis, provided accessory help for generation of PFC, and produced IL 1 equally well as measured in costimulator assays. Splenic T cells of aged Lewis rats, however, were poorly responsive in mitogen assays and did not respond to supplemental IL 2 and antigen with blast transformation and with increased help for B cells to produce PFC. "Old" B cells did not respond in vitro to mitogens with help from M phi and T cells, nor did they respond to B cell helper factor with increased PFC. The data indicate that hyporesponsiveness of the immune system, especially of B cells, in aged rats is due in part to defective reactivity to interleukins and cytokine(s) and to defective cell-cell cooperation.     

Phaseolus vulgaris phytohaemagglutinin (PHA) binds to the human T lymphocyte antigen receptor.

The interaction of phytohaemagglutinin (PHA) with the human T lymphocyte antigen receptor (Ti) was explored. Nonidet-P40 lysates of surface-labelled HPB-ALL cells were immunoprecipitated with PHA, using a rabbit anti-(PHA)-serum, as well as clonotypic monoclonal antibodies (H1-2D4 and T40/25) and a rabbit antiserum (R-43) against Ti. One- and two-dimensional SDS-polyacrylamide electrophoresis under reducing and non-reducing conditions showed that both the clonotypic antibodies and PHA precipitated a disulphide cross-linked heterodimer having a mol. wt. of approximately 79 000 (unreduced) and a comprising subunits of mol. wts. approximately 50 000 and 39 000 (reduced). Further evidence that PHA binds Ti was obtained by (i) cross-immunodepletion with H1-2D4 and PHA; (ii) immunoprecipitation with H1-2D4 of a glycoprotein fraction specifically eluted from a PHA immunoprecipitate; (iii) immunoprecipitation with PHA of a solubilised H1-2D4 immunoprecipitate; (iv) 2-D (non-equilibrium pH gradient electrophoresis/SDS) analyses of H1-2D4 and PHA immunoprecipitates, indicated that H1-2D4 and PHA recognise coincident beta polypeptides. PHA also binds a Ti-like disulphide cross-linked heterodimer on tonsil lymphocytes and two other T-cell leukaemias (HUT-78 and J6). The data further suggest that PHA and R-43 recognise a subpopulation of Ti molecules on HPB-ALL cells that are not bound by H1-2D4, suggesting that there may be at least two forms of Ti. Similar experiments indicate that Concanavalin A (Con A) and wheat germ agglutinin (WGA) also probably bind Ti, whereas Helix pomatia agglutinin (HPA) does not.     

In vitro induction of lymphocyte responsiveness by a Strongylus vulgaris-derived mitogen

Proliferation in vitro of peripheral blood lymphocytes both from horses infected with Strongylus vulgaris and from helminth-free ponies was observed in the presence of extracts of the fourth and fifth stage larvae and adults of S. vulgaris. In addition, S. vulgaris extracts induced transformation in cultures of peripheral blood lymphocytes from sheep and dogs and in mouse spleen cell cultures. Nylon wool non-adherent, T cell enriched fractions of lymphocytes from both mice and horses were stimulated by the S. vulgaris larval mitogen while no proliferation was observed in cultures containing nylon wool adherent, B cell enriched fractions. Macrophage co-operation appeared not to be necessary for S. vulgaris mitogen-induced transformation of spleen cells. The S. vulgaris mitogen stimulated a subpopulation of mouse spleen cells different from those responsive to PHA, Con A and LPS. These cells might be T helper cells since B cells were stimulated to proliferate in the presence of both T cells and S. vulgaris larval mitogen. In addition, the supernatant of in vitro cultured larvae of S. vulgaris induced slight, but significant transformation of equine peripheral blood lymphocytes. Therefore, it is possible that the S. vulgaris mitogen released by both viable parasites and degenerating larvae might induce T cell dependent production of immunoglobulin in vivo and account for the beta-globulinaemia, of which IgG(T) is a major component, in S vulgaris infected horses.     

Pressor responsiveness to angiotensin in soy-fed spontaneously hypertensive rats

Dietary soy may attenuate the development of arterial hypertension. In addition, some soy-containing foods exhibit angiotensin-converting enzyme (ACE) inhibitory properties. Accordingly, we tested the hypothesis that ACE inhibition contributes to the antihypertensive effect of dietary soy. Mean arterial blood pressure (MAP) was recorded from conscious spontaneously hypertensive rats (SHR) at least 24 h after the implantation of catheters. Cumulative dose-response curves to intravenous angiotensin I (AI) (5-100 ng x kg(-1) x min(-1)) and angiotensin II (AII) (1-20 ng x kg(-1) x min(-1)) were constructed for male, sham-operated female, and ovariectomized female (OVX) SHR that were maintained on either casein or soy diets. The soy diet was associated with a significant reduction in baseline MAP in the OVX SHR (approximately 20 mmHg, 1 mmHg = 133.322 Pa). AI and AII infusions caused graded increases in MAP in all groups. However, there was no significant attenuation of the pressor responses to AI in the soy-fed SHR. Conversely, we observed a significant rightward displacement of the AII dose-response curves in the soy-fed sham-operated and OVX SHR. We conclude that ACE inhibition does not account for the antihypertensive effect of dietary soy in mature SHR.     

The decline in murine splenic PHA and LPS responsiveness with age is primarily due to an intrinsic mechanism

Changes in splenic B and T lymphocyte number and mitogenic activity with age were quantitated in (A X C57BL/6)F1 (AB6F1) hybrid mice. Although both the B and T lymphocyte proliferative reactivity to their respective mitogens, lipopolysaccharide (LPS) and phytohemagglutinin (PHA), declined significantly with age, an earlier and more marked reduction was recorded for the T cell response. The decline in B and T lymphocyte mitogenic activity with age could not be correlated with a corresponding reduction in the percentage of splenic B or T lymphocytes. The main focus of this study was to determine if the reduction in T and B lymphocyte mitogenic activity with age results primarily from a mechanism intrinsic to the lymphoid lineage itself or from adverse extracellular factors that increase with age. Bone marrow cells (BMC) derived from individual young and old donor AB6F1 mice were transplanted into the neutral environment of young, lethally irradiated syngeneic recipients. Number and mitogenic activity of splenic T and B lymphocytes were recorded for the original BMC donors as well as for the recipients of the young and old BMC lines 9 mo after the BMC transplants. A predominance of the donor (male) rather than recipient (female) karyotype within the mitogen-responding populations of recipient mice confirmed a donor BMC take. The PHA and LPS response levels exhibited by the old donors were 30% and 70% of those of the young donors, respectively. These differences in PHA and LPS reactivity recorded between young and old donors were maintained between recipients of young and old donor BMC lines. Thus, even under the influence of a young recipient environment, old BMC were incapable of giving rise to mitogen responding cells with a functional competence equivalent to that of their younger counterparts. This finding would lend further support to the theory that an intrinsic mechanism is responsible for the decline in murine mitogenic activity with age.     

Factors affecting the differentiation of epithelial transport and responsiveness to hormones

Under standard culture conditions, epithelial cells grow with their basal surface attached to the culture dish and their apical surface facing the medium. Morphological and functional markers are located in the appropriate plasma membrane, and transepithelial transport occurs in a variety of cultured epithelia. As a result of the polarity of the cells and the presence of tight junctions between cells, on standard tissue culture dishes there is restricted access of growth medium to the basolateral surface of the epithelium, which is the surface at which nutrient exchange normally occurs. Greater differentiation of epithelial cultures can be achieved by growing primary cultures or continuous cell lines on permeable surfaces such as porous bottom cultures dishes in which the porous bottom is formed by a filter or membrane of collagen, or on floating collagen gels. In many cultures, differentiation varies with the time after the culture was seeded. Certain chemicals that accelerate differentiation in nonepithelial cells also accelerate the differentiation of epithelial cultures. Ultimately, defined media and specific substrates for cell attachment should lead to further differentiation of epithelia in culture.     

Differential covariation in taste responsiveness to bitter stimuli in rats

Variation exists in the sensitivity of individual rodents and humans to different bitter tastants. An absence of uniform correlation in responsiveness to different bitter substances across individuals within a species suggests heterogeneity in the mechanisms underlying stimulus processing within this taste modality. Here, we examined taste responsiveness of individual rats to three bitter compounds (quinine hydrochloride, denatonium benzoate, and cycloheximide) in short-term lick tests to determine the magnitude of covariation among responses to these stimuli and infer commonalities in their receptor and neural mechanisms. Rats were tested with a given pair of bitter stimuli during three sessions comprising randomized trial blocks of six concentrations of each stimulus + deionized water. Psychophysical functions were generated for individual rats for respective stimulus pairs, and concentrations of each stimulus that produced equivalent lick suppression relative to water were correlated across animals. Behavioral taste responsiveness to quinine hydrochloride strongly covaried with responsiveness to denatonium benzoate (r = +0.82). Lick responsiveness to quinine was less robustly correlated with that to cycloheximide (r = +0.44), and denatonium and cycloheximide responses failed to correlate. These results imply substantial overlap in the bitter taste coding mechanisms for quinine and denatonium but some degree of independence in the mechanisms responsible for gustatory processing of cycloheximide. More generally, these data reinforce the notion that bitter taste processing is not a homogeneous event.