Specific unresponsiveness of recirculating lymphocytes ater exposure to histocompatibility antigen in F 1 hybrid rats

Effect of in vivo exposure to allogeneic cells upon subsequent in vitro T cell responses and upon allograft rejection

The effect of intravenous injection of 10(6) BALB/c spleen cells into C57B1/6J recipients was assayed by both mixed lymphocyte culture (MLC) of recipient lymphocytes, and by grafting donor (BALB/c) thyroids into recipient mice. It was observed that a single intravenous injection produced depression of proliferative and cytotoxic T cell responses in MLC of spleen, lymph node and peripheral blood lymphocytes of the recipients. This effect was specific for the sensitizing genotype (MLC of recipient and third-party CBA/H lymphocytes was unaffected), and persisted for several days after sensitization. The pattern of this diminished response suggested that the effect was due to a combination of recruitment of reactive lymphocytes from peripheral lymphoid populations, and the generation of alloantigen (H-2?)-specific suppressor T cells in the spleen. In contrast to these findings in vitro, a similar sensitization led only to accelerated rejection of thyroid allografts in vivo.

Influence of secondary inoculum of tumour cells on growth of primary tumour

The effect of successive inocula of tumour cells given to rats at intervals of 1 to 10 days was examined. If W256 cells were injected on both occasions, the second inoculum failed to grow if given into the footpad as early as 1 day, or intravenously as soon as 4 days, after the first administration. However, although a second inoculum failed to grow, it produced significant augmentation of the growth of the primary implant if given during its latent or growth phases. If the second inoculum contained cells from a fibrosarcoma unrelated to W256, its growth was effectively curtailed if the initial inoculum had preceded it by 24 h or more. However, secondary inocula of fibrosarcoma cells did not augment the growth of the primary W256 tumour.

The induction of specific resistance in F1 hybrid rats to local graft-vs.-host reactions: nature of the eliciting cell

A specific state of resistance to local graft-vs.-host (GVH) reactions can be induced in F1 hybrid rats, derived from Ag-B incompatible matings, as a consequence of inoculation with low numbers of parental strain lymphocytes. The magnitude of GVH resistance is markedly and directly dependent upon the number of parental strain lymphocytes used in the pretreatment regimen. The relevant constituents of the resistance-inducing parental cell population are thymus-derived (T) lymphocytes possessing immunologic competence for host alloantigens. B cells, themselves incapable of inducing GVH resistance, adversely effect the induction or display of this effect by T cells.

Helper function of T cells depleted of alloantigen-reactive lymphocytes by filtration through irradiated F1 hybrid recipients. I. Failure to collaborate with allogeneic B cells in a secondary response to sheep erythrocytes measured in vivo

Helper T cells were obtained by injecting heavily irradiated semiallogeneic mice with lymph node cells from H-2-incompatible parental strain mice primed with sheep erythrocytes (SRC) 2 mo before. Thoracic duct lymphocytes collected from the recipents 18-40 h later (nearly all of which were theta-positive and of donor origin) were totally and specifically unresponsive against host-type determinants in mixed-lymphocyte culture. The filtered cells were transferred to irradiated semiallogeneic mice together with SRC and anti-theta-serum-treated (B) cells from SRC-primed syngeneic, semiallogeneic, or allogeneic mice. When antibody-forming cells were measured in the spleen 5-9 days later, effective IgM and IgG collaborative responses were observed with both syngeneic and semiallogeneic B cells but not with allogeneic B cells. No evidence was found that the failure to obtain collaboration with the allogeneic B cells was due to inhibition of the B cells by the T cells or vice versa.

The effect of cyclophosphamide and methotrexate on the 'field effect' or unresponsiveness observed in the rat and mouse GvHR

The Field effect is the decreased biological response to a second challenge in the graft versus host reaction (GvHR). Treatment of recipeint rats or mice during the initial GvHR by methotrexate or cyclophosphamide effected the secondary unresponsivienss. Methotrexate and cyclophosphamide demonstrated different temporal responses indicating different mechanisms of their immunosuppresdive activities.

Specific positive selection of lymphocytes reactive to strong histocompatibility antigens

Selected populations of thymus-derived (T) rat lymphocytes having specific immunological reactivity to chosen histocompatibility (H) alloantigens are found among the cellular products of the mixed lymphocyte interaction (MLI). Such specific selection seems to depend on (a) the antigen-induced proliferation of specific H antigen reactive cells (HARC), and (b) the disappearance of nonreactive cells from the cultures. When the surviving cells from this lymphocyte-antigen interaction are transferred into thymectomized, X-irradiated, marrow-reconstituted syngeneic recipients (B rats) which lack detectable T-lymphocyte functions, the lymphocyte populations subsequently recovered from the hosts possess the capacity to react in the MLI and in the graft-vs.-host (GVH) reaction, and the reactions have specificity for the original priming alloantigens. In addition, these findings identify the cell that reacts in the MLI with the GVH reactive cell.

The origin of cell surface immunoglobulin of marrow-derived and thymus-derived lymphocytes of the rat

The origin of immunoglobulin on the surface of TDL in the rat has been studied by comparing the binding of purified alloantibodies recognizing the Ig-1a allotype of rat light chain, with that of rabbit antirat Fab antibodies. Both reagents labeled all TDL from rats of the DA strain (Ig-1a) with two categories of cells being detected; one binding 100-2,000 molecules of antibody, the other 10,000-100,000 molecules. These categories were likely to be synonomous with T and B cells, respectively. The [(125)I]antiallotype antibodies did not bind to TDL from rats of the PVG/c strain (Ig-1b). When the binding to TDL from (PVG/c x DA)F(1) animals was studied it was found that allelic exclusion occurred in the heavily labeled cells, but not in the lightly labeled ones. Furthermore, when lymphocytes of one allotype were transferred to irradiated recipients of the opposite allotype and recovered from the TDL or spleen of the recipient 20-30 h later, the immunoglobulin on heavily labeled cells was of the donor type, while that of lightly labeled ones bore the recipient marker. Thus heavily labeled cells (B lymphocytes) had synthesized their own immunoglobulin while lightly labeled cells (T lymphocytes) had acquired theirs passively by adsorption. The class of immunoglobulin on lightly labeled cells was also studied and it was found that [(125)I]anti-IgM antibodies bound to an extent approaching the [(125)I]anti-Fab binding, while [(125)I]anti-IgG(2a+2b) antibodies gave much less binding.

Effect of recent antigen priming on adoptive immune responses. II. Specific unresponsiveness of circulating lymphocytes from mice primed with heterologous erythrocytes

When thoracic duct lymphocytes (TDL) or mesenteric lymph node (MLN) cells from mice primed 1 day before with either sheep erythrocytes (SRC) or horse erythrocytes (HRC) were transferred together with both SRC and HRC to irradiated mice, antibody responses measured 7 days later could not be detected to the priming antigen but were high to the other antigen. Furthermore, this unresponsiveness of TDL and MLN to the priming antigen could not be abrogated by delaying antigen challenge of the transferred cells for 1-2 wk. Previous work had shown that short-term priming with antigen also induced specific unresponsiveness in spleen cells on adoptive transfer. Unresponsiveness in these cells, however, was only of temporary duration, full recovery in the reactivity of the cells being observed when challenge with the priming antigen on transfer was delayed for 5 or more days. Since the present work showed that such recovery from initial unresponsiveness on transfer was unique to spleen cells and did not apply to TDL or MLN, it appeared that different mechanisms were responsible for the unresponsiveness in the three populations. It is proposed that the unresponsiveness detected in TDL and MLN cells in the present study resulted from a deficiency of antigen-reactive cells, these cells having been recruited to the spleen, i.e., a region of antigen concentration. This concept of antigen-induced selective recruitment of circulating lymphocytes was supported by evidence that (51)Cr-labeled heterologous erythrocytes indeed localized largely in the spleen after intravenous injection but not in MLN.

Effect of recent antigen priming on adoptive immune responses. I. Specific unresponsiveness of cells from lymphoid organs of mice primed with heterologous erythrocytes

When spleen, mesenteric lymph node, or Peyer's patch cells from mice primed 24 h before with either sheep erythrocytes (SRC) or horse erythrocytes (HRC) were transferred together with both SRC and HRC to irradiated mice, antibody responses measured 7 days later were very low to the priming antigen but high to the other antigen. This was demonstrated either by measuring numbers of antibody-forming cells in spleen or levels of hemagglutinins in serum. Specific unresponsiveness of the transferred cells was evident in both the 19S and 7S responses. It was observed only when strict experimental conditions were followed: (a) the cell donors had to be primed with not less than 10(9) erythrocytes given intravenously; (b) the cells had to be transferred between 1 and 2 days after antigen priming; (c) antibody responses in the recipients were measured within 7 days of cell transfer, i.e., partial recovery was evident by 11 days; (d) the transferred cells had to be challenged in the recipients within 1 day after cell transfer: when challenge was delayed for 5 days or longer, responsiveness returned. The failure of cells from recently primed donors to respond to the priming antigen on adoptive transfer could be overcome by supplementing with normal spleen cells, but not with thymus alone or bone marrow alone. This implied that unresponsiveness occurred at the levels of both T and B lymphocytes, and was not due to a suppressive influence exerted by T cells. Further work is in progress to determine the mechanism of this transient state of specific unresponsiveness.

The specific selection of recirculating lymphocytes by antigen in normal and preimmunized rats

Thoracic duct lymphocytes (TDL) from normal rats will restore a primary antibody response to sheep erythrocytes (SRBC) in irradiated recipients and cause a graft-versus-host reaction in F(1) hybrid rats; lymphocytes from rats immunized with either tetanus toxoid or dinitrophenylated bovine gamma globulin (DNP BGG) will generate specific antibody after cell transfer and challenge. The ability of TDL to mediate each of these responses is severely depressed by giving a single intravenous dose of the specific antigen shortly before cannulation of the thoracic duct, although the lymphocyte donors themselves respond normally. The injection of antigen does not decrease the output of lymphocytes in the thoracic duct and the effect is specific for the antigen injected. The findings are most readily accounted for by assuming that small subpopulations of specific lymphocytes are selected from the recirculating pool by antigen which has localized in lymphoid tissue. The observation that passive antibody abolishes selection by SRBC supports this interpretation. The strong selection exerted by a subcutaneous injection of SRBC in Freund's complete adjuvant, which induces delayed hypersensitivity but little early antibody, suggests that a common cell type may be involved in the induction of both delayed hypersensitivity and antibody formation. The anti-DNP antibody response generated by TDL from rats immunized with DNP BGG was abolished by a selecting injection of the homologous conjugate. The response was depressed to a smaller degree by injections of either BGG or dinitrophenylated human serum albumin, suggesting that carrier-specific (T) and hapten-specific (B) lymphocytes could be separately selected from the recirculating pool. The regional selection of recirculating lymphocytes by antigen may explain a number of phenomena in which the prior injection of antigen has been found to inhibit a subsequent immune response.