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New short-lived strains of mice (SAM-P), which have been developed by Takeda et al. (1981), show a defective antibody response to T dependent (TD) antigen in vitro, as demonstrated in the accompanying paper (see page 419). In the present study, we investigated the cellular site of the defect, using a cell culture system. In this paper, it is demonstrated that T-helper (Th) cell activity for the antibody response to TD antigen is impaired, while other cellular immune responses, e.g. mixed leucocyte reaction, cytotoxic T-lymphocyte response, and delayed-type hypersensitivity reaction, are normal. These results suggest that the defect in T-helper subset is limited in helper function for the antibody response, and that the helper function for the cell-mediated immune responses is intact. These two functions of the T-helper subset are apparently regulated in a different manner. The SAM-P strains of mice may thus serve as an appropriate model for studying functional heterogeneity in T-helper/inducer cell subsets. [ABSTRACT FROM AUTHOR]

A receptor which binds secretory lgA (sIgA) is expressed on human T cells from patients with systemic lupus erythematosus, rheumatoid arthritis, Behcet's syndrome and IgA nephropathy and on normal T cells following phytohaemagglutinin (PHA) stimulation. The specificity of this receptor was initially probed with a panel of normal serum immunoglobulins in competitive inhibition assays with sIgA using two-colour immunofluorescence. While the receptor showed the strongest affinity for igAl (IC5010-6 M), IgD which has a similarly glycosylated hinge region to IgAl, also bound to the receptor (IC50 10-5 M). IgA2, which lacks the 'O'-glycosylated hinge region, did not significantly inhibit the binding at these concentrations suggesting that the IgA determinants for this receptor might be the oligosaccharides present in the hinge region of IgAl. IgAl has up to 10 'O'-linked oligosaccharides and four N-linked oligosaccharides per molecule. In order to probe the role of the 'O'-linked hinge sugars in the binding event, a sugar library was prepared from IgAl by a procedure designed to release 'O'-linked oligosaccharides preferentially, and to retain them in the natural closed ring formation. The sugars were released by hydrazinolysis at 65° and the resulting oligosaccharide library analysed by high voltage paper electrophoresis (HVE) and P4 gel permeation chromatography. Competitive inhibition studies demonstrated that both the library and the individual 'O'-linked sugars associated with IgA1 were implicated in the binding of IgAl to this receptor (IC50 between 1 × 10-5 M and 6 × 10-s M). Within this range the individual sugars showed small differences in their affinity for the receptor in the following order: Galβ3GalNAc = NeuNAc2α3(6)Galβ3GalNAc > NeuNAc2α3(6)Galβ3[NeuNAc2α6]GalNAc ≥ GalNAc. [ABSTRACT FROM AUTHOR]

This paper describes a T-cell targeting strategy based on the use of an antigen-monoclonal antibody heteroconjugate. A rat anti-idiotypic monoclonal antibody specific for a murine B-cell lymphoma was conjugated to the purified protein derivative (PPD) of tuberculin. This construct selectively delivered up to 4.5 &times 104 molecules of PPD onto each tumour cell. Targeted PPD was internalized for endosomal processing and was presented in association with the I-A class II restriction element to PPD-reactive T-helper (Th) cells. Activated Th cells were demonstrated to proliferate and secrete significant levels of tumour necrosis factor (TNF). Such lymphokine secretion was observed at a PPD concentration as low as 1 ng/mI. Despite the secretion of TNF, the S-cell lymphoma was found to be resistant to autonomous Th-mediated cytotoxicity. Targeted Th cells did, however, activate tumourcidal macrophages that subsequently mediated significant tumour cytostasis. Based on this observation, it is proposed that the targeting system described may be exploited as the basis for a future immunotherapeutic strategy. [ABSTRACT FROM AUTHOR]

Lectins can be used to detect changes in cell-surface glycosylation. In this paper we examine the lectin-binding characteristics of murine T cells as measured by flow cytometry. A large panel of labelled lectins was used to stain naive, activated and resting murine T cells. Some lectins did not detectably bind any T cells, some bound to all T cells and some bound to only a subset of splenic T cells. Three lectins which preferentially bind to previously activated T cells were identified: Bandeiraea simplicifolia BS-I, Bauhinia purpurea and Lycopersicon esculentum. In addition, two lectins were found to bind preferentially to activated T cells; Glycine max and Triticum vulgaris. Finally, no differences were found in the ability of a large panel of lectins to bind to Th1 and Th2 clones. Lectin binding may be a powerful tool for distinguishing naive, activated and memory T cells. [ABSTRACT FROM AUTHOR]

As described in an accompanying paper, trinitrophenyl (TNP) modification of pork insulin (PI) at the A1 glycine position allows this molecule to stimulate a proliferative response in H-2b (B10) mice. We now show that this antigen stimulates low IgG responses in the same strain of mice. Our results show that T-cell help and proliferation may therefore be regulated independently. [ABSTRACT FROM AUTHOR]

The thoracic duct or efferent prescapular duct was cannulated in four fetal calves aged 121-259 days post-conception. The duration of lymph flow ranged from 2 to 20 days and the mean flow rates sustained over these collection periods varied from 54 to 488 ml/hr. Lymphocyte output ranged from 44 × 106 cells/hr in thoracic duct lymph from a 121-day fetus to 3.9 × 108 cells/hr in efferent prescapular lymph from a 259-day fetus. The circulating lymphocyte pool in fetal calves of about 120 and 190 days gestational age was calculated to contain, respectively, 4 × 108 cells and 2 × 1010 cells. The proportion of lymphocytes bearing surface immunoglobulin detected in fetal lymph ranged from 2.1% to 8.7%. Recirculating lymphocytes from fetal calves produced strong proliferative responses when stimulated by T-cell mitogens but responded poorly to B-cell mitogens. Fetal lymphocytes also responded to stimulation by allogeneic cells and stimulated other cells to proliferate during mixed lymphocyte culture. When stimulated with Con A, fetal lymphocytes secreted IL-2 to a degree that was indistinguishable from the secretory behaviour of lymphocytes from adult animals. The results presented in this paper show that chronic lymphatic fistulae can be established successfully in fetal calves to give access to recirculating lymphocytes. This provides a new experimental approach for studying the development of the bovine immune system. [ABSTRACT FROM AUTHOR]

T-colony formation can be induced in PHA-stimulated peripheral blood mononuclear cells (PBM) from man, but not in PHA-stimulated purified T cells, the latter requiring the presence of factors produced by PHA-stimulated PBM and termed T-colony promoting activity (TCPA). In this paper, we demonstrate that interleukin-2 (IL-2), the growth hormone of T lymphocytes, controls T-colony formation. We show that: (i) IL-2 activity and TCPA produced by PHA-activated PBM are co-purified by gel filtration and chromatography on blue agarose, a procedure which yields a 850-fold IL-2 purification; (ii) recombinant IL-2, produced by genetically manipulated Eseherichia coli, can induce T-colony formation in PHA-stimulated purified T cells; (iii) Monoclonal antibody against the IL-2 receptor (anti-Tac antibody) completely inhibits the T-colony formation in PHA-stimulated PBM when directly added to the culture system. [ABSTRACT FROM AUTHOR]

In this paper we present experiments that indicate that, in man, most T-celI subpopulations produce interleukin-2 (IL-2), but that the main cell subpopulation which produces it, both upon activation with phytohaemagglutinin or in autologous mixed lymphocyte cultures, is that of autologous rosette-forming (Tar) T4+ T cells. Conversely, the main IL-2-responding T-cell subpopulation is that composed of T cells depleted of Tar (T-Tar) that are T8+ IL-2 was also found to be more effectively produced by Tar cells that do not bind peanut agglutinin (PNA) than by those that do. The PNA T4+ Tar cells were also found to respond best to interleukin- I (IL-I). [ABSTRACT FROM AUTHOR]

Sera from mice with large tumours from a variety of tissue types and sources have been shown to contain substances capable of suppressing the proliferative response of normal mouse lymphocytes to concanavalin A (Con A), bacterial endotoxin (LPS) and allogeneic cells. The present paper deals with studies on the nature of these inhibitory materials using mainly a methylcholanthreneinduced rhabdomyosarcoma in DBA/2J mice. It was found that a material responsible for inhibition of the Con A response eluted with immunoglobulins on Sephadex G-150 and eluted with monomeric immunoglobulin on Sephadex G-200. The component of tumour-bearer serum responsible for the suppression of the LPS response of normal lymphocytes eluted from Sephadex G-150 with the α and β globulins and albumin (molecular weight < 150,000). The immunoglobulin-containing serum fraction from tumour-bearing animals inhibited the mixed lymphocyte response, Con A response, and specific immune response to purified protein derivative (PPD) in allogeneic cell systems. It also inhibited the in vitro primary response of mouse cells to sheep red blood cells, and, to a lesser extent, the response to a T cell-independent antigen (DNP-dextran). The inhibitory activity continued to elute with monomeric IgG on Sephadex G-200 when columns were run in 1640 medium and adjusted to pH 2.5, indicating that an acid dissociable complex was not responsible for inhibitory activity. Inhibitor activity could be removed by absorption on immunoadsorbents containing goat anti-mouse immunoglobulin, and could be recovered by acid elution from the adsorbent. Inhibitor activity was not removed by immunoadsorption on columns prepared with antisera to chicken immunoglobulin. [ABSTRACT FROM AUTHOR]