Biomedical subjects
Publications and source records attributed to R B Ashman.
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Cytotoxic T-cell (Tc) immunity to influenza A virus in mice persists for at least 2 years. Both T-helper (Th) and Tc cells are present and fully functional in old mice; however, the frequency of memory Tc-cell precursors declines with age.
Infective influenza virus primes mice and increases at least ten-fold the level of splenic cytotoxic T-memory and precursor cells in comparison with normal mice. Intranasal virus infection or intraperitoneal injection of infective virus results in frequencies of 1-2 x 10(-4) cytotoxic T-cell precursors in spleen as determined by limiting dilution assays. With both types of immunization, T-helper cells amplifying the generation of T-killer cells are limiting, and optimal clone frequencies depend on addition of excess T-helper cells. We find that at least part of the T-helper cells amplifying the generation of cytotoxic T cells are cross reactive for the type A influenza viruses and therefore have a similar virus specificity to type A influenza-specific cytotoxic T cells (tc). Help for T-killer cells can be replaced by supernatants derived from Concanavalin A-stimulated rat spleen cells, but presence of antigen is still required to stimulate the Tc precursor or memory cells before they respond to antigen non-specific T cell-growth factor(s) present in the stimulated rat spleen cell medium.
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Mice injected with inactivated (UV light-irradiated) influenza virus produce specific antibody, become sensitized for a delayed-type hypersensitivity reaction, but do not generate specific cytotoxic T (Tc) cells. If injected 4-5 days later with infectious virus, the formation of Tc cells is suppressed by > 90%. If A strain viruses are used, the suppression observed is cross-reactive within A strain viruses but does not extend to B/LEE or to Sendai virus. Serum from mice injected with UV-irradiated virus contains antibodies which on adoptive transfer can inhibit Tc cell formation when infectious homologous virus is used to challenge the recipients. Spleen cells from the same mice, upon adoptive transfer, also inhibit (50-70%) Tc cell formation if transferred within 24 h of injection of infectious virus, and the specificity pattern observed is cross-reactive within A strains. The activity of the cells mediating suppression is destroyed by monospecific anti-Thy-1.2 antibody and complement. The immune cells require I region sharing between donor and recipient mice for their suppressor activity to be effective. (There is also a partial requirement for K, D region sharing, but the possible rejection of transferred cells is not excluded.) Dilution assays in which clonal expansion of Tc precursors is used to estimate their frequency and the presence of T helper (Th) cells indicate that suppressed mice possess Tc precursors and primed cells which, upon restimulation, act as Th cells. Furthermore, injection of irradiated Th cells with inactivated virus does not significantly reduce the ensuing suppression.
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We demonstrate here: (a) the existence of T helper (Th) cells that augment the generation of virus-specific cytotoxic T cells in vitro, (b) that the helper cells carry the theta and Ly 1 membrane antigens, (c) that activation of the Th effect is specific for viral antigens, and (d) that the delivery of help is not H-2 restricted.
Two different BALB/c anti-CBA (H-2k)monoclonal antibodies that bind to Kk and Dk antigens blocked Tc cell-mediated lysis of L929 (Kk, Dk) target cells, but with quite different specificity. One antibody (30R3) powerfully blocked Kk-specific lysis mediated by alloreactive or Kk-restricted Tc cells immune to ectromelia, Sendai, or influenza viruses. The other antibody (27R9) blocked these anti-Kk Tc cells much less than 30R3, but in contrast, 27R9 blocked anti-Dk lysis much more than 30R3. Most importantly, 27R9 strongly blocked Dk-restricted anti-influenza Tc cells, but did not significantly block Dk-restricted anti-Bebaru (BEB) lysis. This result indicated that different H-2 determinants coded in the D end of H-2k were recognized by influenza-and BEB-immune Tc cells. These determinants may be carried on two different molecules coded by the H-2D and H-2L loci, but other possibilities are not yet excluded.
Leucocytes from purified protein derivative (PPD) skin test positive individuals, after exposure to PPD in vitro, show a significant increase in nitroblue tetrazolium (NBT) dye reduction when compared to leucocytes from PPD negative donors. The active principle was shown to be soluble, and was released from lymphocytes after a rapid, immunologically specific interaction with the sensitising antigen.
Lymphocytes cytotoxic for mouse embryo fibroblasts (MEF) infected with murine cytomegalovirus (MCMV) were produced by in vitro culture of "memory" spleen cells with UV-irradiated, MCMV-infected, MEF. Cytotoxic lymphocytes were developed from spleen cells of mice 10 to 240 days after infection with MCMV. The cytotoxic cells carried the theta and Ly 2 antigens, and were H-2 restricted in the recognition of infected target cells.
Intact quokkas (Setonix brachyurus) were grafted with thymus and skin as neonates. Fifty seven percent of primary thymus grafts persisted when donors were less than 32 days of age, compared with only 20% when the dornors were juveniles. This suggested that neonatal tissue was more readily accepted than tissue from adult animals. When the recipients had left the pouch, induced tolerance was tested by grafting thymus and skin from the original donors. Second thymus grafts were generally unsuccessful; however, second skin grafts were accepted and remained intact over the three-year period of observation, provided that the hosts were less than about 40 days of age at the time the first graft were placed.
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Human peripheral blood mononuclear cells which mediate antibody-dependent cellular cytotoxicity (ADCC) against herpes simplex virus- (HSV) infected target cells consist of both adherent (MA) and nonadherent (MNA) effector cell populations. These two cell populations can be distinguished by their different phagocytic properties and morphologic appearance, their requirement for antibody in the ADCC reaction, and the rapidity with which they lyse target cells in the presence of immune serum. The MA cells are predominantly phagocytic and have the morphologic characteristics of monocyte-macrophages, whereas the MNA cells are nonphagocytic and appear to be small to medium-sized lymphocytes. Optimal expression of ADCC by MA cells requires higher concentrations of immune serum than does MNA cell-mediated ADCC. MA-mediated cell killing is first detectable by 8 hr and reaches completion after 24 hr of incubation. In contrast, MNA-mediated ADCC produces target cell damage by 2 hr and reaches completion at 8 hr of incubation. Unlike MNA effector cells, the MA effector cells are profoundly inhibited after preincubation with either latex or silica particles. The HSV immune status of the donor had no effect on the ability of either cell population to mediate ADCC. These data demonstrate the participation of both nonadherent mononuclear cells, presumably K cells, and monocyte-macrophages, in ADCC directed against HSV-infected target cells.