Transplantation of allogeneic lymphoid cells specifically depleted of graft versus host reactive cells

Selection of antigen-specific cells by adherence to allogeneic cell monolayers: cytolytic activity, graft-vs.-host activity and numbers of adherent and nonadherent cells

Rat lymph node cells taken at the peak of cytolytic activity following a skin allograft were separated into adherent and nonadherent fractions by incubation on monolayers of thoracic duct lymphocytes either of the same strain as the graft donor or of an Ag-B different strain. In the face of a 3-fold enrichment of cytolytic activity in the adherent cells and a 3-fold depletion in the nonadherent cells there was no detectable partition of graft-vs-host (GVH) activity. Supplementary experiments supported the simplest interpretation of this finding, namely that the antigen receptors on GVH-reactive cells did not influence their adherence in this system. Similarly, there was no partition of the GVH activity of nonimmune lymph node cells by adherence. Labeling lymph node cells with either radioactive uridine or thymidine in vitro, suggested that about 20% of DNA-synthesizing cells in the immune population adhered because of antigen recognition.

Ly and Ia phenotype of suppressor T cells induced by graft-vs.-host reaction

Suppressor T cells were generated in (CBA X C57BL)F1 mice undergoing graft-vs.-host (GvH) reaction and treated with anti-Ly and anti-Ia antisera to determine their membrane antigen phenotype. Pretreatment of CBA-induced GvH suppressor T cells with anti-Ly-1.1, anti-Ly-2.1 or anti-Iak antisera plus complement abrogated their suppressive properties when tested against primed F1 spleen cells in vitro. In contrast, concanavalin A (Con A)-induced suppressor T cells were insensitive to anti-Ly-1.1 serum. It is concluded that GvH-induced suppressor T cells are Ly-1+,2+,3+,Ia+, and thus distinct from Con A or antigen-induced suppressor T cells.

In vitro induction of cell-mediated immunity to murine leukemia cells. II. cytotoxic activity in vitro and tumor-neutralizing capacity in vivo of anti-leukemia cytotoxic lymphocytes generated in macrocultures

The main findings of the present study are: (a) highly reactive cytotoxic lymphocytes (CTL) against syngeneic and allogeneic murine leukemia cells were generated in vitro in macro 'one-way' mixed leukocyte-tumor cultures (MLTC). Cultures set up in large tissue culture flasks contained up to 400 X 10(6) normal spleen cells (responder cells) and 20--40 X (10(6) mitomycin C-treated leukemia cells (stimulator cells). Successful sensitization in macrocultures was greatly dependent upon the responder cell density and the responder/stimulator cell ratio. Cytotoxic activity, as measured by the 51Cr-release assay, peaked on day 5--7. (b) Sensitized 'memory' lymphocytes produced in primary MLTC could be restimulated with the original tumor cells to give a more rapid and stronger secondary cytotoxic response. (c) lymphocytes sensitized to allogeneic leukemia cells reacted equally well with sensitizing leukemia cells and with the corresponding normal lymphoid target cells, whereas lymphocytes sensitized to syngeneic leukemia cells did not react with the homologous normal lymphocytes. (d) Cryopreserved normal splenocytes and leukemia cells were as efficient as fresh cells in generating allogeneic and syngeneic CTL. (e) Using a Winn-type tumor neutralization assay, it was shown that both allogeneic and syngeneic splenocytes sensitized in vitro to EL4 leukemia (of C57BL/6 mice) and to YAC leukemia (of A mice) were capable of preventing tumor growth in the syngeneic host, whereas cultured normal splenocytes frequently showed a tumor-enhancing effect. Long-term survivors, remaining after inoculation of leukemia cells and sensitized lymphocytes, also became resistant to a tumor challenge that was up to 10,000 greater than the minimum lethal dose.

Specific elimination of cytotoxic effector cells. I. Adsorptive behavior of effectors and their precursors and spleen cell monolayers

Monolayers formed of normal mouse spleen cells attached to polystyrene coated with poly-L-lysine were tested for their ability to bind specifically antigen-reactive cells in normal or primed mouse spleen. 88 to greater than 98% of the activity of cytotoxic populations was removed by a single adsorption. However, normal spleen cells or spleen cells previously primed in vitro could not be depleted of their capacity to be sensitized, even when adsorption effectively removed all residual cytotoxic activity from the same previously primed population. In fact, exposure to an immunoadsorbent augmented the ultimate cytotoxicity generated in a nonspecific fashion. This augmentation was especially dramatic in the case of a previously primed population and may have reflected the removal of a nonspecific suppressor. If antigen-reactive precursors cannot be removed efficiently by adsorption, other approaches to the generation of tolerant lymphoid populations, such as specific suppression of precursor differentiation must be sought.