Expansion of natural killer (NK) and natural killer-like T (NKT)-cell populations derived from patients with B-chronic lymphocytic leukemia (B-CLL): a potential source for cellular immunotherapy

Abstract

B-cell chronic lymphocytic leukemia (B-CLL) is the most common leukemia in the Western world. It is currently an incurable disease, making new treatment options such as immunotherapy desirable. Monoclonal antibodies (Mabs) to surface antigens of the tumor cell is one option. Administration of cytotoxic cells such as natural killer (NK) and natural killerlike T (NKT) cells expanded in vitro might be a useful treatment modality alone or in combination with MAbs. A limiting step in the development of successful cellular immunotherapy has been the availability of appropriate cytotoxic cells. Here, we report the feasibility of expanding populations of the human killer cells, CD3ÀCD56 þ NK and CD3 þ CD56 þ NKT cells, from peripheral blood mononuclear cells (PBMCs) of B-CLL patients. The influence of tumor B cells on the in vitro expansion of killer cells was assessed by depleting B cells from PBMCs by microbead separation before culture. The 21-day cultures from both B-cell-and non-B-cell-depleted PBMC showed a marked expansion of NK cells, and also of T cells, among which almost half had the NKT phenotype. Depletion of B cells before culture did not change the expansion rates of NK and NKT cells significantly. In patients with progressive B-CLL, NK cell expansion capacity was improved after fludarabine treatment when compared to samples obtained before treatment. Repeated samples of PBMCs from individual untreated patients with both indolent and progressive disease cultured under identical conditions gave similar NK cell expansion rates. Expanded killer cell populations had cytotoxic function against the NK-sensitive target K562 cell line and expressed high levels of Granzyme B. From our studies, we conclude that NK cells as well as NKT cells from the peripheral blood of B-CLL patients can be expanded, and that these cells have cytotoxic capacity.

Analysis of CD16+CD56dim NK cells from CLL patients: evidence supporting a therapeutic strategy with optimized anti-CD20 monoclonal antibodies

“…15,16 This hypothesis was suggested by the restoration of their functional activity after interferon (IFN)-a and/or interleukin (IL)-2 treatment. 17,18 We conducted the first extensive characterization of the phenotypic and cytotoxic qualities of NK cells from CLL patients and compared them with those of healthy subjects. Our data reveal that NK cells from these patients have the major phenotypic features of competent NK cells and are able to function effectively.…”

Mono- and dual-targeting triplebodies activate natural killer cells and have anti-tumor activityin vitroandin vivoagainst chronic lymphocytic leukemia

“…In CLL patients, high burden of malignant B cells in peripheral blood naturally reduces NK cell proportion and negatively affects the natural and antibody-dependent cytotoxicity of the latter. 3,12 Laprevotte et al reported the median NK:B cells ratio as 0.02:1 in CLL patients and further showed that IL-15 could expand patients' NK cells, which in turn elevated CLL cell depletion by anti-CD20 antibodies (Rituximab and GA101). 12 To check whether increasing NK: B cells ratio also enhances the killing activity of the immunoligand, we purified NK cells from both patients 3 and 4 and incubated with purified CLL cells in autologous setting.…”

“…46,47 Ex vivo expansion of NK and NKT cells from healthy donors and CLL patients have shown exciting results, where Guven et al reported even better expansion rates for functionally active NK cells from CLL patients despite initial low numbers. 3,48 However, possible side effects of immunoligand-associated NK cell activation in patients such as autoimmune reactions toward healthy B cells should be considered. Limitations of autologous and allogeneic NK cell infusions have been discussed elsewhere 49 and must be pointed out in the context of adoptive transfer of NK cells with immunoligand.…”

“…1,2 It is characterized by progressive outgrowth of monoclonal CD5 C /CD19 C double positive B cells in peripheral blood, bone marrow as well as lymph nodes and spleen. 3 Therapeutic monoclonal antibodies have positively contributed toward the management of CLL. 2,4 A chimeric anti-CD20 antibody-rituximaband a humanized anti-CD52 antibody-alemtuzumab-have been recently introduced for the treatment of progressive diseases.…”

“…12 This is supported by ex vivo expansion of NK cells within the PBMC population from CLL patients, which enhances natural as well as antibodydependent NK cell activity. 3,12 Additionally, shedding of NKcell-activating ligands from the surface of tumor cells is another important immune escape mechanism. 1,13 Soluble NKG2D ligands including sMICA, sMICB and sULBP2 are of prognostic relevance in CLL.…”