In vitro elicitation of cytotoxic response against a nonimmunogenic murine tumor by allosensitization

Abstract

The murine lymphoma (thymoma) PIR-2 of C57BL/6 origin, primarily induced in our laboratory by fractionated X-ray irradiation, has been shown to be nonimmunogenic by its failure to immunize syngeneic mice in vivo or to evoke a cytotoxic response in primary mixed lymphocyte-tumor cell cultures (MLTC) in vitro. We were able, however, to demonstrate the existence of anti-PIR-2 cytotoxic cells among allogeneic-primed C57BL/6 responding lymphocytes using the technique of limiting dilution cultures (LDC). The frequency of anti-PIR-2 cytotoxic cells among C57BL/6 lymphocytes sensitized against BALB/c splenocytes in mixed leukocyte culture (MLC) was 1/20 to 1/40, and the cytotoxic activity of positive LDC wells against PIR-2 reached 60% as determined by a 4-h 51Cr-release assay. The frequency of anti-PIR-2 cytotoxic cells could be increased two- to 10-fold (up to 1/4) by removing nylon-wool-adherent cells from the primed cell population and/or by enriching the primed lymphoblast population on a Percoll density gradient. Anti-PIR-2 cytotoxic cells were found to be Thy1+; Lyt1-2+ cells. Clones isolated from the LDC wells manifested strong cytotoxic activity toward PIR-2 cells and the stimulating BALB/c splenocytes but not against other H-2b tumor lines or C57BL/6 splenocytes. We suggest that the procedure of allostimulation in MLC-LDC is an effective in vitro means of generating highly reactive cytotoxic cells against poorly immunogenic neoplasms.

Tolerance induction by megadose hematopoietic progenitor cells: expansion of veto cells by short-term culture of purified human CD34+ cells

“…To measure CTL reactivity, we used the method described by Rachamim et al 10 and established in mouse studies by Leshem et al 18 Briefly, this method makes use of secondary MLRs to amplify the initial signal. We found this to be important because of the low signal observed in a marked proportion of our studies in which CTL reactivity was measured at the end of primary MLRs.…”

Auto-tumor lysis by blood lymphocytes in vitro

“…Activation of lymphocytes for auto-tumor lysis can occur in MLC [1,14,17,18,22,28,35]. We showed that in these cultures distinct alloreactive populations coexist.…”

“…Lymphocytes stimulated in conventional MLC can often lyse autologous tumor cells [1,14,17,18,22,28,35]. When lymphocytes from one ovarian carcinoma patient were stimulated in MLC, the admixture of tumor cells (rhabdomyosarcoma) from the "stimulator" patient altered the lysis of autologous tumor only marginally and the lysis of these rhabdomyosarcoma cells was not inhibited by admixture of the autologous tumor cells (Fig.…”

Clinical adoptive chemoimmunotherapy with allogeneic alloactivated HLA-haploidentical lymphocytes: controlled induction of graft-versus-host-reactions

“…Destruction of the tumor cells is presumably through recognition of major and minor HLA on the tumor cell surface [2,9,21]. AIloactivation of human PBL using pooled allogeneic donor L 9t 440 18 90 59 280 52 250 52 250 Patient M 87 1700 8 150 80 1500 95 1800 80 1500 The PBL were obtained 6 days after infusion of the combined MLC-activated and TCGF-expanded donor lymphocytes from patients L and M. Daring this time both patients we.re experiencing grade III GVHR but had not begun treatment with methylprednisolone.…”