PREPARATION OF HUMAN ADHERENT LYMPHOKINE-ACTIVATED KILLER (A-LAK) CELLS

Abstract: Adherent lymphokine activated killer (A-LAK) cells have been prepared from peripheral blood mononuclear cells (PBMC) which have been treated with a lower alkyl ester or an amide of an amino acid such as phenylalanine to deplete monocytes.

Description: TITLE Preparation Of Human Adherent Lvmphokine-Activated Killer (A-LAK) Cells Background of the Invention Natural killer (NK) cells and lymphokine-activated killer (LAK) cells have been implicated in immuno- surveillance against tumor cells (Barlozzari et _______ (1983) J. Immunol. 111:1024; Rayner et ______ (1985) Cancer 55:1327). It has been reported that the systemic administration of autologous LAK cells and IL- 2 to patients with certain advanced cancers is beneficial (Rosenberg (1988) Immunology Today 9:58). LAK cells were prepared at concentrations of up to, but not exceeding, lxlO 6 cells/mL. The process of preparing LAK cells for cancer therapy is very cumbersome and tedious since a large number of cells are needed per treatment for each patient. Also, the treatment of cancer patients by LAK/IL2 therapy is accompanied by significant toxicities (Rosenberg et ______ (1987) N. Enol. J. Med. 316:889). It has been previously shown that monocytes interfere with the generation of LAK activity by IL-2 (Hoyer et aJL (1986) Cancer Res. 46:2834). L-leucine methyl ester (LeuOMe) and L-phenylalanine methyl ester (PME) were shown to remove monocytes from human peripheral blood mononuclear cells (PBMC) (Thlele and Lipsky (1985) J. Immunol. 134:786; Hoyer et aL. (1986) Cancer Res. 46:2834). Furthermore, LeuOMe also depleted NK activity and NK cells (Thlele and Lipsky (1985) J. Immunol. 134:786; Hoyer et aL. (1986) Cancer Res. 46:2834). We have shown that depletion of monocytes by PME allows generation of LAK cells by rIL-2 at cell densities of 5xl0 6 cells/mL or higher (European patent application 87107755.8, published December 2,1987, and allowed U.S. application 07/038361, filed April 20, 1987). It has been reported recently that a highly enriched LAK cell population can be obtained by selecting "adherent" LAK (A-LAK) cells, which can be isolated by adherence to plastic of 24-hr IL-2-activated and onocyte-depleted PBMC (Melder et al. (1988) Cancer Res. 48:346). These cells are highly proliferati e and cytotoxic, and are enriched for Leu 19-positive cells; Leu 19 expression correlates with NK and LAK activity. The potential advantages and importance of A-LAK cells for adoptive im unotherapy in humans are: A-LAK cell preparations are relatively enriched for LAK cells with higher levels of antitumor activity; A-LAK cells may be effective in doses containing lower numbers of cells than conventional LAK therapy; less IL-2 may be needed for co-administration with A-LAK cells to patients, thereby reducing the toxicity of the therapy. In previous procedures to prepare A-LAK cells, monocytes are removed by their adherence to nylon-wool columns or by centrifugal elutriation in order to generate A-LAK cells (Melder et aL. (1988) Cancer Res. 48:34). These procedures for monocyte removal are tedious and complicated. Also, some LAK cell precursors may adhere to the nylon-wool columns, reducing the efficiency, of the process to generate A- LAK. Summary of the Invention The present invention provides an improved process for preparing adherent lymphokine activated killer (A-LAK) cells. The process comprises: a. treating peripheral blood mononuclear cells (PBMC) to deplete monocytes; b. culturing the remaining cells in culture medium containing IL-2 to generate lymphokine-activated killer (LAK) cel l s, in a container to which a portion of the LAK cel l s adhere; c. removing the non-adherent cells; d. culturing the adherent LAK cells in medium conaining IL-2 to expand the adherent LAK cells. The improvement comprises in step a depleting monocytes by treating the PBMC with a lower alkyl ester of an L- amino acid selected from the group consisting of alanine, aspartic acid, cysteine, glutamic add, glutamine, phenylalanine, proline, tyrosine, tryptophan, and valine, or an amide of an L-amino acid selected from the group consisting of leucine, isoleucine, phenylalanine and valine, or a pharmaceutically suitable salt of said ester or amide. Description of the Preferred Embodiments The preferred L-amino acid is phenylalanine or tyrosine and most preferred is phenylalanine. The lower alkyl group of the ester can be methyl, ethyl, propyl , isopropyl, butyl, isobutyl or t-butyl but is preferably methyl or ethyl and is most preferably methyl. Preferred pharmaceutically acceptable salts are the hydrogen chloride and hydrogen bromide salts. The use of PME and other lower alkyl amino acid esters in a process to prepare LAK cells is disclosed in European patent application 87107755.8, published December 2, 1987, and allowed U.S. application 07/038361, filed April 20, 1987, which are incorporated herein by reference. We have employed PME at concentrations of about 1 to 5 mM as a single step for onocyte depletion. We have discovered that it is possible to generate A-LAK from PME-treated PBMC. We have found that treatment of PBMC with PME prior to culturing the A-LAK cells in plastic containers, results in a substantial increase in the level of expansion of the A-LAK cells, relative to the expansion in cell number obtained in the absence of PME treatment. During the expansion of the A-LAK cells, following treatment with PME, the LAK cell functional cytolytic activity remains high. It was also discovered that the optimal concentration of PME used in the process, in terms of maximizing A-LAK cell expansion, depended on the cell density at which the A-LAK cells were first cultured in plastic containers. At a cell concentration of 2xl0 6 cells/mL, the optimal PME concentration was about 1 M; at a cell density of lxlO 7 cells/mL, the optimal PME concentration was about 5 mM. The results suggest that PME depletes a subset of PBMC that inhibit the expansion of A-LAK cells and that, at higher PME concentrations, a separate PBMC subset, which enhances A-LAK cell expansion, is depleted. The present invention involves an improved process for the expansion and enrichment of Leu 19-positive lymphocytes with high lytic activity. PBMC are first treated with PME to remove monocytes and other PME- sensitive cells. The resulting lymphocytes are incubated with rIL-2 in plastic flasks for 1 to 2 days. The adherent cells are then cultured for 8 to 21 days to obtain an increase in cell number and LAK activity. The cell densities used during the A-LAK preparation process, including the monocyte depletion step, are preferably about 5xl0 6 to 2xl0 7 cells/mL, more preferably about lxlO 7 to 2xl0 7 cells/mL. We have also discovered that A-LAK cells can be generated from PBMC treated with phenylalaninamlde (PheNH2). Our procedure using PME provides several substantial differences and Important advantages over the procedures previously used to prepare A-LAK cells (Melder et aL, (1988) Cancer Research 48:3461-3469). First, we used PME as a chemical agent to deplete monocytes from PBMC. This procedure can be better controlled by PME concentration and time of incubation with PME than can be achieved using the nylon-wool procedure. PME treatment of PBMC is also much more convenient and less time consuming to use than centrifugal elutriation which requires an elaborate setup, sterilization procedure, and the running of the elutriation. Second, in the process of the invention, the lymphocytes are cultured in plastic containers at a cell density of about 1 to 2xl0 7 /mL, as compared with 2xl0 6 /mL which has been used previously. Thus, the present process will reduce the total volume of medium used by 5 to 10-fold, relative to previous procedures for the preparation of A-LAK cells. Third, the high cell density (lxl0 7 /mL) generally gave more reliable expansion than low cell density (lxl0 6 /mL). Fourth, enriched A-LAK cells can be generated from PBMC completely depleted of monocytes, but they are not as proliferative. The amount of monocyte depletion can be precisely controlled by the PME concentration used to treat the PBMC. As described above, the level of monocyte depletion cannot be readily controlled using elutriation and/or the nylon-wool column method of depleting monocytes. A-LAK cells can be detached from plastic flasks and transferred to DuPont SteriCell® bags (DuPont) for culture. A-LAK cells can be generated and cultured 1n serum-free medium, such as AIM-V. The procedure employing PME-treated PBMC lends itself well to a process where relatively large volumes of blood and cell numbers are required, as 1s the case for adoptive immunotherapy. Furthermore, the A-LAK cells are highly enriched for the cytotoxic and proliferative cells. The use of A-LAK cells in adoptive immunotherapy should give a better understanding of the importance of LAK cells in the immunosurveillance of tumor cells and therapy for human cancer. Example 1 We have studied the generation of A-LAK cells from PBMC treated with PME. PBMC were treated with 1 or 5 mM PME and cultured at 2xl0 6 cells/mL or lxlO 7 cells/mL with rIL-2 for 1 day in plastic flasks (Table 1). Nonadherent (NA) cells were removed and cells adherent to flasks were cultured with the conditioned media containing rIL-2 for 8 days. The resultant A-LAK cells were cytotoxic against 51 Cr-labeled K562 and Raji target cells. A-LAK cells are also highly proliferative and have a high percent composition of the Leu-19 phenotype of NK and LAK cells. At the low cell density (2xl0 6 cells/mL), partial depletion of monocytes by 1 mM PME resulted in greater levels of cellular expansion of A-LAK cells than were obtained using 5 M PME. At the high cell density (lxlO 7 cells/mL), 5 mM PME resulted in higher levels of cellular expansion than did 1 mM PME. Higher cellular expansion levels were observed with the 1 mM PME- treated PBMC, at both high and low cell densities, than with the untreated PBMC. Our results demonstrate that PME treatment of PBMC provides an efficient means to generate A-LAK cells for adoptive immunotherapy. Table 1 Generation of A-LAK Cells from PBMC Treated with Various PME Concentrations PBMC were treated with 0, 1, or 5 mM PME for 40 min. at a concentration of lxlO 7 cells/mL. The various cell preparations (30 mL) were then incubated with 400 U/mL of rIL-2 at total cell densities of 2xl0 6 cells/mL or lxlO 7 cell/mL in T75 flasks overnight. The culture medium containing non-adherent cells was removed, the non-adherent cells were separated from the medium, the medium was returned to the flasks, and the adherent (A) cells were cultured. The data shown are for cells cultured for 8 days. E:T ratio shown 1s 5:1 for LAK activity against Raji. Example 2 PBMC were treated with 5 mM PME and incubated with 400 U/mL of rIL-2 overnight at a cell density 2xl0 6 /mL, 5xl0 6 /mL or lxl0 /mL. IL-2 units are 1n Biological Response Modifier Program (BRMP) units (U). Non- adherent cells were decanted from the flasks. The adherent cells 1n the flasks were washed and counted. Conditioned medium (100%) was added back to the flasks for culture. The number of cells that adhered to the flasks increased with the initial adherent cell density. After 10 days in culture, the LAK activity and % Leu 19-positive cells were essentially the same amongst the three adherent cell densities. However, the fold expansion was found to increase with increasing cell density used during the process. Table 2 Generation of A-LAK Cells from PME-Treated PBMC at Various Cell Densities PBMC were treated with 5 mM PME and incubated with 400 U/mL rIL-2 overnight at the various cell densities. NA cells were cultured with 400 U/mL rIL-2 at lxl0 6 /mL. The culture medium containing non-adherent cells was removed, the non-adherent cells were separated from the medium, the medium was returned to the flasks, and the adherent (A) cells were cultured. The data shown are for cells cultured for 10 days. E:T ratio shown is 5:1 for LAK activity against aji. Example 3 We have found that L-phenylalaninamide (PheNH2) also depletes monocytes without adversely affecting NK cells. The generation of A-LAK cells from PBMC treated with PheNH2 was compared with that obtained using PME treatment. As summarized in Table 3, the % Leu 19-positive cells and LAK activity from PheNH2-treated PBMC were only slightly less than those of PME-treated PBMC. However, the number of A-LAK cells at day 8 was generally much higher from the PheNH2~treated PBMC than from the PME-treated PBMC. This result may be due to the fact that PheNH2 at 5 mM is less effective than PME at 5 mM in depleting monocytes. Thus, a higher number of monocytes presumably remain in the PheNH2-treated PBMC and, as we have shown 1n Example 1, this low level of monocytes (1 to 10% of the total cells) appears to be optimal for maximal A-LAK cellular expansion. PBMC were treated with 5 mM PME or 5 mM PheNH2- The A-LAK were generated using a total cell density of the culture of 5xl0 6 cells/mL. E:T ratio shown is 5:1 for LAK activity against Raji. Data shown were from four different donors. NT = not treated. Although the invention has been described with reference to the preferred embodiments, PME and PheNH2, the procedures and conditions described are also applicable to use in the A-LAK process of the other esters and amides mentioned in the summary of the invention.

Claims: WHAT IS CLAIMED IS: 1. In a method of activating and expanding cells for use in adoptive immunotherapy which comprises: a. treating peripheral blood mononuclear cells (PBMC) to deplete monocytes; b. culturing the remaining cells in culture medium containing IL-2 to generate lymphokine- activated killer (LAK) cells, in a container to which a portion of the LAK cells adhere; c. removing the non-adherent cells; d. culturing the adherent LAK cells in medium containing IL-2 to expand the adherent LAK cells; the improvement which comprises in step a depleting monocytes by treating the PBMC with a lower alkyl ester of an L-amino acid selected from the group consisting of alanine, aspartic acid, cysteine, glutamic acid, glutamine, phenylalanine, proline, tyrosine, tryptophan, and valine, or an amide of an L-amino acid selected from the group consisting of leucine, isoleucine, phenylalanine and valine, or a pharmaceutically suitable salt of said ester or amide. 2. Process of claim 1 wherein in step a the PBMC at a cell concentration in the range of about lxlO 6 to 2xl0 7 cells per mL are treated with the amino acid ester or amide at a concentration in the range of about 1 to 5 mM, and in step b the PBMC are cultured for about 1 to 2 days at a cell concentration in the range of about lxlO 6 to about 2xl0 7 cells per mL. 3. Process of claim 2 wherein in step b the PBMC are cultured in plastic flasks and in step d the adherent LAK cells are cultured in the same plastic flasks or in closed gas-permeable plastic bags in the medium from step b for about 8 to 21 days. 4. Process of claim 3 wherein in step a the PBMC concentration is about 2xl0 6 cells per mL and the cells are treated with phenylalanine methyl ester or phenylalaninamide at a concentration of about 1 mM. 5. Process of claim 3 wherein in steps a and b the PBMC concentration is in the range of about 5xl0 6 to 2xl0 7 cells per L and in step a the cells are treated with phenylalanine methyl ester or phenylalaninamide at a concentration of about 5 mM. 6. Process of claim 5 wherein in steps a and b the PBMC concentration is in the range of about lxlO 7 to about 2xl0 7 cells per mL. 7. Process of claim 6 wherein in steps a and b the PBMC concentration is about lxlO 7 cells per mL.

Inventors: LEUNG KAM HUNG, LEUNG, KAM, HUNG
Applicants: DU PONT, E.I. DU PONT DE NEMOURS AND COMPANY
Application year: 1990
Main classification: C12N5
IPC codes: A61K35, A61P37, C12N5, C12R1