Search

Exposure to 600 rad of X-irradiation 3 h after primary immunization with chicken erythrocytes (CRBC) abolished the production of antibodies and the generation of killer T cells, but scarcely affected the induction of delayed footpad reactions. Exposure to irradiation 3 h after secondary immunization reduced only slightly the generation of killer T cells and reduced slightly or substantially the production of antibodies. Delayed reactions persisted for long periods after elicitation in irradiated, boosted mice. Cross-reactivity between CRBC and quail erythrocytes (QRBC) was very weak with respect to the tyrotoxicity, antibody and delayed reaction raised after primary immunization. Those raised after secondary immunization with the homologous antigen showed some degrees of cross-reactivity to another antigen. The booster with QRBC in CRBC-primed mice augmented the response to CRBC with respect to the induction of cytotoxicity and delayed footpad reaction, but only weakly affected the response with respect to the production of antibody. Therefore, effector cells of cytotoxicity and delayed footpad reaction showed greater degrees of cross-reactivity than antibody-producing cells during an anamnestic response. The cross-reactive response raised after secondary immunization was radioresistant with respect to cytotoxicity and delayed footpad reaction but radiosensitive with respect to antibody production. Cytotoxicity to immunizing antigen was inhibited by the unlabelled homologous antigen. Cytotoxicity to a cross-reacting antigen was inhibited by the same cross-reacting antigen and also by an immunizing antigen. There may exist heterogeneous populations of cytotoxic lymphocytes with different abilities to recognize antigens. [ABSTRACT FROM AUTHOR]

Direct cytotoxicity raised at an early interval after immunization with chicken erythrocytes (CRBC) has been ascribed to θ-positive, immunoglobulin (Ig)-bearing lymphocytes. Cytotoxicity of such effector cells was not affected by trypsinization. Cytotoxity was reduced by the treatment of effector cells with anti-IgG serum and complement or by the addition of anti-IgG serum to culture medium for cytotoxicity test. When the effector cells were treated with trypsin before cytotoxicity test, such procedures with anti-IgG serum did not affect their cytotoxicity, Ig molecules on cytotoxic T lymphocytes may not be an essential element for antigen recognition. This explanation may he supported by the fact that cytotoxicity against CRBC could be raised in 600 tad irradiated, thymus-cell transferred mice in the absence of antibody production. [ABSTRACT FROM AUTHOR]

Immune responses were examined after immunization with chicken erythrocytes (CRBC) in mice, Cytotoxicity of spleen cells was assessed by the release of 51Cr from labelled target cells. (1) At early stages (day 4–7) after primary intraperitoneal immunization, direct cytotoxicity of spleen cells was raised efficiently in C57BL/6 and AKR mice, but not in C3H,/He, SL and DDD mice. Delayed hypersensitivity and antibody production were raised to almost the same extent in all the strains at such periods. (2) Effector cells in direct cytotoxicity were θ-positive and IgG-positive, and glass-nonadherent and Nylon wool column-adherent. Effector cells in antibody-dependent cell-mediated cytotoxicity in the presence of antibody to CRBC were eliminated by treatment with anti-IgG serum, but not by treatment with anti-θ serum. (3) Cytotoxicity and antibody production were raised efficiently after intraperitoneal or intravenous immunization, but not after footpad immunization. On the other hand, delayed hypersensitivity developed most efficiently after footpad immunization. [ABSTRACT FROM AUTHOR]

The effect of neonatal thymectomy at various times after birth (Tx-1, Tx-7) on effector and suppressor I cells responsible for cell-mediated cytotoxicity (CMC) for allogeneic antigens was deter- mined. Following in-vitro primary mixed lymphocyte cultures, in the absence of T-cell growth factor (TCGF), alloreactive CMC was not detected in spleen cells of Tx-1 mice, but was detected in spleen cells of Tx-7 mice at as high levels as in those of sham-operated mice. However, in the presence of TCGF, as much alloreactive CMC was detected in spleen cells of Tx-1 mice as in those of Tx-7 mice. Furthermore, TCGF production was not detected in spleen cells of Tx-1 mice but was detected in those of Tx-7 mice. In in-vivo experiments, inhibition of allogeneic tumour growth and CMC in spleen cells showed the same pattern as in in-vitro experiments. These results sup- port the concept that the reduction of CMC in Tx-I mice might be due to a defect in helper function (TCGF-producing capacity) rather than to a defect in cytotoxic T lymphocytes and/or cytotoxic T lymphocyte precursors. Alloreactive suppressor T cells could not be induced in spleen cells of Tx-1 mice but were induced in spleen cells of Tx-7 mice. Therefore, it was suggested that alloreactive suppressor T cells require the presence of the thymus for 7 days after birth in their development. [ABSTRACT FROM AUTHOR]

Effects of thymectomy at various times after birth on cytotoxicity, delayed footpad reaction and antibody production were examined in 6 week old mice immunized intraperitoneally with chicken erythrocytes. Cytotoxicity and antibody production were abolished by thymectomy within 3 days after birth. Mice thymectomized at 5 days of age or later showed appreciable degrees of cytotoxicity and antibody production. On the other hand, a delayed footpad reaction could be elicited even in mice thymectomized within 24 h after birth, although the degree of the reaction was reduced by such a treatment. Therefore, T cells responsible for delayed hypersensitivity were less thymus-dependent and required the presence of the thymus for a shorter period in their development that those responsible for cytotoxicity or antibody production. [ABSTRACT FROM AUTHOR]

While immunization with allogeneic spleen cells did not generate positive cytotoxic activity, it produced accelerated rejection of subsequent turnout grafts carrying the same H-2 antigen. No augmented generation of cytotoxicity was dctectable by 51Cr-release assay in the host spleen cells, even in the presence of accelerated rejection of turnout allografts. However, augmented cytotoxicity was generated in mixed lymphocyte culture and in peritoneal lymphocytes after an intraperitoneal boost. These results indicate that while immunization with allogeneic spleen ceils does not generate mature cytotoxic T lymphocytes (CTL) detectable by the present assay, it may produce premature CTL that rapidly differentiate into mature CTT, after direct contact with antigen at the site of graft rejection. The inability to generate a high degree of cytotoxicity in the spleen cells may be ascribed to the early development or CTL at the rejection site. The relationship between accelerated rejection of allogeneic tumour grafts and delayed-type hypersensitivity reactions is also discussed. [ABSTRACT FROM AUTHOR]

Effects of whole body irradiation with 600 rad on delayed hypersensitivity, direct cytotoxicity and antibody production were examined in mice immunized with chicken erythrocytes (CRBC) or sheep erythrocytes (SRBC) in saline. Delayed footpad reactions to CRBC were not affected by the exposure to irradiation 3 h before or after antigenic stimulation. On the other hand, direct cytotoxic activities in spleen cells and antibody titres to CRBC were reduced by such exposures. Additionally, delayed footpad reactions to SRBC were not affected by the exposure to irradiation. Generation of effector cells responsible for delayed footpad reactions proved to be resistant to irradiation. [ABSTRACT FROM AUTHOR]