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In different murine systems, delayed-type hypersensitivity (DTH) swelling responses at 24–48 hr after antigen challenge were preceeded by an early 2-hr swelling response. The 24-hr DTH response is thought to depend on this early (DTH-initiating) hypersensitivity response. In this paper we show that in the syngeneic DBA/2-SL2 routine turnout system only an early 2-hr swelling response can be evoked. This early hypersensitivity response was tumour specific and serotonin dependent. The early hypersensitivity response in contact hypersensitivity has been ascribed to antigen-specific T-cell factors. To test whether similar T-cell factors were involved in the early hypersensitivity response in this syngencic turnout system, we have transferred lymph node, spleen lymphocytes and scram from immunized mice into naive recipients. The serum was fractionated in two fractions, a 50,000–80,000 MW fraction, and a 120,000–190,000 MW fraction. In recipients of lymphocytes, total serum and the 50,000–80,000 MW fraction of the serum, an early hypersensitivity response can be evoked. So, these data suggest the involvement of specific T-cell factors in the development of an early hypersensitivity response against syngeneic tumour cells. Despite the development of an early (DTH initiating) hypersensitivity swelling response these immunized animals cannot develop a classical 24-hr swelling response. This absence of the 24-hr response in the presence of the 2-hr response is discussed in relation to the frequently observed immune suppression in tumour-bearing mice. [ABSTRACT FROM AUTHOR]

Previous work from this laboratory has shown that preimmunization of syngeneic hosts with Rous sarcoma virus (RSV)-transformed cells elicits a strong immune response against the growth of transplantable RSV sarcomas, mediated by T lymphocytes expressing the surface phenotype of helper cell precursors (Prat, Di Renzo & Comoglio, 1983). This paper shows that anti-tumour immunity may be elicited in tumour-bearing animals by triggering an experimentally pre-amplified T-helper cell population at the site of tumour growth. Mice were treated with cyclophosphamide (which inactivates suppressor T cells) followed by skin sensitization to trinitrochlorobenzene (TNCB) according to a protocol that has been shown to induce an appreciably amplified generation of trinitrophenyl (TNP)-reactive helper T cells (Fujiwara et al., 1984). Five weeks after TNCB painting, mice were transplanted s.c. with a lethal dose of RSV-induced syngeneic sarcoma cells; the injection at the tumour site of TNCB induced the regression of the tumour in mice in which the TNP-helper cell population has been amplified, but not in controls, including those injected with a non-related hapten or sensitized to TNCB without inactivation of suppressors. [ABSTRACT FROM AUTHOR]

This paper uses B-lymphocyte cloning methods to quantify the effects of anti-μ chain antibody on immature and mature B cells. Nude mouse spleen lymphocytes were incubated with various concentrations of sheep anti-mouse μ chain antibody for times varying from 10 min to 24 h. They were then washed and plated in the agar B-cell colony formation assay. Five to six days later, control B cells had developed into colonies with a plating efficiency of about 5%. B cells from newborn mice pretreated with anti-μ yielded fewer colonies. Remarkably low concentrations sufficed to inhibit subsequent mitogenesis. For example, 3 μg/ml acting for 1 h or 0.1 μg/ml acting for 24 h gave > 50% inhibition. Adult B cells were about thirty-fold more resistant to negative signalling. Immature cells became more profoundly inhibited as anti-μ treatment was prolonged. Anti-Ia or anti-H2 antibodies, in the absence of complement, did not deliver a negative signal. Anti-μ pretreatment also reduced the capacity of immature B cells to form clones of anti-hapten antibody-forming cells in a liquid microculture system where the triggering stimulus was a T-cell independent antigen. Mature 'T-independent' B cells were not inhibited. Populations of hapten-specific B cells prepared by the hapten-gelatin method were investigated in the agar cloning system. Pretreatment of immature cells with anti-μ reduced their capacity to form colonies, this subpopulation of cells behaving like unfractionated B cells. Furthermore, hapten--HGG delivered a negative signal also. Mature hapten-specific cells or unfractionated immature spleen cells formed normal numbers of colonies following hapten HGG treatment. Overall, the studies support the view that anti-μ antibody and hapten--HGG deliver strong negative signals to immature but not mature cells with appropriate receptors. The value of anti-μ as a model, universal tolerogen was supported. Fluorescence-activated cell sorter (FACS) analysis was performed to study the relationships between functional inhibition and Ig receptor modulation. We confirmed that the IgM receptors of immature B cells are more readily modulated by anti-μ antibody than those of mature cells. Furthermore, the receptor regeneration could be partially inhibited amongst immature but not mature B cells. There was not a close quantitative relationship between the degree of modulation and the degree of functional inhibition. The results did not support the view that irreversible receptor modulation as such was the cause of functional inhibition. [ABSTRACT FROM AUTHOR]

Lymph node and spleen cells from normal mice were cultured for 3 days with polyoma virus-induced tumour, Ehrlich's ascites turnout or leukaemia L 1210 cells. This resulted in in vitro immunization of the lymphocytes, which were then transferred to irradiated target cells labelled with 51Cr. Normal, i.e. non-immune thioglycollate-stimulated peritoneal macrophages were also added to some tubes. Non-immune macrophages mixed with immunized lymphocytes showed a significantly increased ability to destroy tumour ceils as compared with macrophages in the absence of immunized lymphocytes. The immunized lymphocytes were almost entirely inactive alone. When the number of macrophages was kept constant the cytotoxicity was dependent on the number of viable immunized lymphocytes placed on the target cells. Immunized lymphocytes, in the presence of macrophages, only exhibited strong killing of the target cells against which they had been immunized; some lysis of ‘bystander’ cells was, however, seen provided specific target cells were present. Macrophage monolayers exposed to immunized lymphocytes upon contact with specific antigen became ‘armed’ and showed a significant cytotoxicity for specific target cells. When immunized lymphocytes and normal macrophages were treated with actinomycin D and puromycin, cytotoxicity was inhibited in the immunized lymphocytes but not in the macrophages. The possible mechanism of normal macrophage cooperation with immunized lymphocytes in the cytotoxic killing reaction is discussed. Results presented in this paper favour the view that immunologically specific cytophilic factor (presumptive cytophilic antibody) is involved in the macrophage-mediated cytotoxicity in the system studied. [ABSTRACT FROM AUTHOR]