Characterization of HNK-1+ (Leu-7) human lymphocytes. III. Interferon effects on spontaneous cytotoxicity and phenotypic expression of lymphocyte subpopulations delineated by the monoclonal HNK-1 antibody

Strong natural killer (NK) cell activity in bone marrow of myeloma patients: accelerated maturation of bone marrow NK cells and their interaction with other bone marrow cells

Bone marrow natural killer (NK) cell activity was studied in patients with multiple myeloma. Bone marrow mononuclear cells from myeloma patients expressed considerable levels of cytotoxicity against K562 in a 4 h 51Cr-release assay, which was comparable to that of blood lymphocytes. In contrast, NK-cell activity was markedly low or absent in bone marrow of normal donors and control patients. Fractionation of bone marrow cells from myeloma patients on linear bovine serum albumin gradients enriched NK effector cells in the upper, lymphocyte-enriched fraction, with no reactivity in the middle fraction containing mainly myeloma cells. Treatment with either Leu-7 or OKMI monoclonal antibody plus complement reduced or abrogated bone marrow NK-cell activity of myeloma patients as well as blood NK-cell activity. However, OKMI plus complement failed to reduce control bone marrow NK-cell activity, although the activity was reduced by Leu-7 plus complement. Overnight exposure to interferon (IFN) of bone marrow cells resulted in an augmentation of NK-cell activity in myeloma patients, but not in controls. Furthermore, adherent bone marrow cells from controls suppressed IFN-induced enhancement of NK-cell activity of blood lymphocytes, whereas bone marrow of myeloma patients did not contain such suppressor cells. No cytotoxicity was induced in control bone marrow cells by cocultivation with bone marrow myeloma cells. Bone marrow NK cells from myeloma patients were able to lyse control bone marrow cells in a 18 h assay and their lytic activity was augmented by IFN treatment. However, neither bone marrow cells nor blood lymphocytes were cytotoxic to autologous and allogeneic fresh myeloma cells even after activation with IFN. These results suggest that NK precursor cells differentiate into HNK-I- and OKMI-positive mature NK cells in bone marrow of myeloma patients, but not in control bone marrow, and that these functional bone marrow NK cells may interact with other bone marrow elements.

Leu 7+ (HNK-1+) cells. I. Selective compartmentalization of Leu 7+ cells with different immunophenotypes in lymphatic tissues and blood

In the present immunohistochemical studies, Leu 7+ (HNK-1+, human natural killer and killer) cells were found to occupy preferentially germinal centres of follicles in lymph nodes and tonsils. Leu 7+ cells were also present in germinal-like zones of spleen follicles and in mantle zones of hyperplastic thymus follicles and varied in localization in lymph nodes involved in different types of follicular centre cell-derived malignant lymphomas. Most of the Leu 7+ cells in the follicles expressed the Leu 3 (helper/inducer) marker. Double staining studies of tonsil sheep erythrocyte-rosetting and peripheral blood mononuclear cell suspensions showed that two main, mutually complementary, subpopulations of Leu 7+ cells could be distinguished in both cases, namely Leu 7+/Leu 4+ (subdivided into Leu 2+ (suppressor/cytotoxic) and Leu 3+) and Leu 7+/Leu 4-, including mostly cells with OKM 1 (myelomonocytic) characteristics. Thus, in the tonsil cell suspension the cells with Leu 7+ Leu 3+/OKM 1- immunophenotype strongly predominated, whereas among peripheral blood mononuclear cells Leu 7+Leu 2+/OKM 1- and Leu 7+/OKM 1+ immunophenotypes were mostly observed.

Depressed levels of granular lymphocytes with natural killer (NK) cell function in 247 cancer patients

The HNK-1 (Leu-7) monoclonal antibody was used to enumerate and characterize the level of blood granular lymphocytes in 247 cancer patients. The results were compared to 146 control individuals. A fluorescence-activated cell sorter was used to purify blood HNK-1+ cells from cancer patients. The monoclonal antibody identified a homogeneous population of granular lymphocytes with greater than 95% purity. Conversely, virtually 100% of HNK-1- cells from cancer patients were agranular lymphocytes. These results were the same as previously observed in normal individuals, where the HNK-1+ cell fraction contained all the lymphocytes with spontaneous cytotoxicity in natural killer (NK) and killer (K) cell assays. The level of HNK-1+ cells in cancer patients correlated significantly with the patient's age and sex, with older individuals having higher levels and male patients containing a higher proportion than female patients. The levels in the cancer patients were significantly lower than normal controls (p = 0.04). When the results were subdivided by the histologic type of cancer, additional differences were noted. Compared to age and sex-matched controls, significantly depressed levels of HNK-1+ granular lymphocytes were observed in 49 patients with colon cancer (9.7% vs. 15.8%, p = 0.0001), 18 patients with lung carcinoma (11.7% vs. 27.0%, p = 0.0001), 24 patients with breast carcinoma (12.0% vs. 15.5%, p = 0.04) and 64 patients with head and neck carcinoma (15.9% vs. 19.1%, p = 0.05). However, there were no significant differences overall in the average HNK-1+ cell level of 66 patients with melanoma (13.0% vs. 13.5%, p = 0.75) and nine patients with sarcomas (15.8% vs. 14.3%, p = 0.71). Thus, this important subpopulation of granular lymphocytes with NK and K cell function was significantly depressed in most cancer patients. Accounting for the patient's age and sex and the histologic type of cancer was critical to interpreting the results.

In vitro propagation of cultured human natural killer cells expressing the HNK-1 differentiation antigen and spontaneous cytotoxic function

Human natural killer (NK) cells expressing the HNK-1 differentiation antigen were established in long-term tissue culture for over 3 months. The fluorescence-activated cell sorter-purified HNK-1+ cells required both phytohemagglutinin and exogenous interleukin 2 to propagate in long-term culture. After 2 weeks of culture, virtually all of the growing cells exhibited the surface membrane phenotype associated with immature HNK-1+ cells, since they simultaneously expressed the HNK-1, Leu-4 and Leu-2a but lacked the M1. Leu-3a and T6 antigens, and Fc gamma receptors. They exhibited a lymphoblastoid appearance, contained cytoplasmic granules, and exhibited spontaneous cytotoxic function against a broader spectrum of target cells than did fresh HNK-1+ cells from the same donor. Cultured HNK-1+ cells lacked antibody-dependent cell-mediated cytotoxic (ADCC) function, while fresh HNK-1+ were fully capable of ADCC function. On the other hand, cultured HNK-1- cells were lymphoblasts without cytoplasmic granules or NK cytotoxic function. The cultured HNK-1+ cells gradually lost their HNK-1 antigen expression over time, although the expression of other surface antigens (e.g., Leu-4 and Leu-2a) was unchanged. With prolonged culture (greater than 2 months), they also exhibited decreasing cytotoxic function and a diminished number of cytoplasmic granules. They were eventually indistinguishable from HNK-1- cells after 3 months of culture. These observations were not influenced by adding interferon-gamma to the cultures. The results demonstrate that the immature form of NK cells (that express T cell antigens) preferentially proliferate in long-term cultures when incubated with phytohemagglutinin and interleukin 2.