CD56 Natural Killer Research Articles

A comparative study of immunomagnetic methods used for separation of human natural killer cells from peripheral blood

Immunomagnetic sorting of natural killer (NK) cells from the peripheral blood of healthy donors has been evaluated in a comparative study of composition, yield and activation of target cells obtained by positive (Dynabeads, Microbeads) and negative (Microbeads) sorting procedures. Positively sorted target cells were selected by expression of the NK cell marker CD56, whereas NK cells obtained by negative sorting were those remaining after steps to remove all non-NK cell leukocyte populations were accomplished. In positive sorting, both CD56 +CD3 − NK cells and CD56 +CD3 + natural killer T (NKT) cells were included. The NKT cell fraction differed between individuals, but not between the positive sorting methods. Whereas 20–30% of positively sorted target cells were NKT cells, only ∼ 3% of negatively sorted cells were CD3 +. Contamination with monocytes and B cells was low (1–3%) in all methods studied. Sorting with Microbeads (both positive and negative) gave higher cell yields than those obtained with Dynabeads (14% vs. 5% of total leukocyte numbers). A higher CD56 fluorescence intensity of NK cells and a better discrimination between the CD56 bright and CD56 dim NK cell subpopulations was obtained after negative sorting. Dynabeads-separated cells had, shortly after separation, a significantly higher expression (∼ 30%) of the early activation marker CD69 than cells either positively or negatively separated by Microbeads (∼ 8%). CD56 + cells positively sorted by Microbeads demonstrated a significantly higher production of TNF-α and IFN-γ after IL-2 stimulation than Dynabeads-sorted cells. However, the cytotoxicity of cells obtained by the two positive sorting procedures did not differ. In conclusion, positive selection of CD56 + cells by Microbeads is better than Dynabeads, as determined from cell yield and procedure-associated cell activation and should be chosen for in vitro studies of NK/NKT cells. However, when pure NK cells and phenotypic subtypes are to be studied, negative sorting seems most appropriate.

Simple enumerations of peripheral blood natural killer (CD56+ NK) cells, B cells and T cells have no predictive value in IVF treatment outcome

To evaluate the association between the absolute counts of the peripheral natural killer (NK) cells (including total CD56(+) NK cells, CD56(dim) NK cells and CD56(bright) NK cells), B cells and T cells on the implantation rate and miscarriage rate after IVF treatment. This was a prospective observation study. A total of 138 patients who underwent IVF treatment from December 2002 to July 2003 were recruited to the study. Blood samples were obtained on the day of vaginal oocyte retrieval prior to the procedure. The absolute counts of lymphocytes, NK cells, B cells and T cells were identified by flow cytometry. These absolute counts and their relationships to IVF treatment outcome and miscarriage rate were analysed. There were no significant differences with regard the mean values of absolute lymphocyte count, T cell count, B cell count and NK cell count (including total CD56(+) NK, CD56(dim) NK and CD56(bright) NK cells) between the pregnant and non-pregnant groups and also between the ongoing pregnancy and miscarriage groups. The cause of infertility, duration of infertility, basal FSH levels, number of previous failed IVF treatments, number of previous miscarriages and stimulation characteristics were not significantly different between the pregnant and non-pregnant groups. Previous studies have suggested that women with a history of recurrent miscarriage and those with infertility accompanied by recurrent failed IVF treatments are associated with a peripheral blood NK cell percentage >12%, therefore further analysis of peripheral CD56(+) NK cell levels <12% (group A) and >12% (group B) was performed. There was no significant difference in implantation rate (group A: 17.0%; group B: 23.2%), pregnancy rate (group A: 36.6%; group B: 47.7%) or miscarriage rate (group A: 23.3%; group B: 28.6%). There were no significant differences between simple enumerations of peripheral blood NK cells (including total CD56(+) NK, CD56(dim) NK and CD56(bright) NK cells), B cells and T cells with IVF treatment outcome and pregnancy outcome. Women who had a peripheral NK cell level >12% did not have higher number of previous pregnancy losses. Importantly their pregnancy rate was not reduced and their miscarriages were not increased compared to women who had a peripheral NK cells level <12%.

Expression of Killer Immunoglobulin‐like Receptors on Peripheral Blood NK Cell Subsets of Women with Recurrent Spontaneous Abortions or Implantation Failures

Decidual natural killer (NK) cells express inhibitory receptors (killer immunoglobulin-like receptors, KIRs), which bind to ligands on trophoblast cells (human leucocyte antigen, HLA-C). This interaction appears to block NK cytotoxicity against trophoblast cells. In this study, we investigated the expression of inhibitory and activating receptors in peripheral blood NK cells of women with recurrent spontaneous abortion (RSA) or implantation failures. CD56(dim)/CD16(+), CD56(bright)/CD16(-) NK cells and CD56(+)/CD3(+) NKT cells of women with RSA or in vitro fertilization (IVF) failures and normal controls were analyzed for the expression of CD158a, CD158b inhibitory KIRs or CD161-activating receptors, by flow cytometric analysis. CD158a and CD158b inhibitory receptor expression by CD56(dim)/CD16(+) and CD56(bright)/CD16(-) NK cells were significantly decreased, and CD161-activating receptor expression by CD56(+)/CD3(+) NKT cells was significantly increased in women with implantation failures when compared with normal controls. An imbalance between inhibitory and activating receptor expression was found in NK cells of women with implantation failures. This imbalance may explain the adverse reproductive outcome.

Reciprocal age related change in natural killer cell receptors for MHC class I

Natural killer (NK) cells are essential for healthy aging. NK cell activation is controlled by MHC class I-specific CD94/NKG2 receptors and killer immunoglobulin-like receptors (KIR). To assess NK cytotoxic function in isolation from MHC receptor engagement, we measured the ability of purified NK cells to kill mouse P815 target cells in the presence of anti-CD16 mAb. CD16-mediated cytotoxicity did not change with age, indicating that NK activation and cytotoxic granule release remained functional. We then investigated MHC class I receptor expression on NK cells. There was an age related decrease in CD94 and NKG2A expression and a reciprocal age related increase in KIR expression. NKG2A expression also declined with age on CD56 + T cells. CD94/NKG2A receptor function was proportional to expression, indicating that NK cell inhibitory signaling pathways were intact. NKG2A and KIR expression were complementary, suggesting that CD94/NKG2A function could substitute for inhibitory KIR function during polyclonal NK cell development in both young and elderly adults. The distinct roles of CD94/NKG2A and KIR receptors suggest that shifting MHC class I receptor expression patterns reflect age related changes in NK cell and CD56 + T cell turnover and function in vivo.

Direct bacterial protein PAMP recognition by human NK cells involves TLRs and triggers α-defensin production

AbstractAlthough human CD56+CD3-natural killer (NK) cells participate in immune responses against microorganisms, their capacity to directly recognize and be activated by pathogens remains unclear. These cells encode members of the Toll-like receptor (TLR) family, involved in innate cell activation on recognition of pathogen-associated molecular patterns (PAMPs). We therefore evaluated whether the 2 bacterial protein PAMPs, the outer membrane protein A fromKlebsiella pneumoniae(KpOmpA) and flagellin, which signal through TLR2 and TLR5, respectively, may directly stimulate human NK cells. These proteins induce interferon-γ (IFN-γ) production by NK cells and synergize with interleukin-2 (IL-2) and proinflammatory cytokines in PAMP-induced activation. Similar results were obtained using CD56+CD3+(NKR-expressing) T cells. NK cells from TLR2-/-mice fail to respond to KpOmpA, demonstrating TLR involvement in this effect. Defensins are antimicrobial peptides expressed mainly by epithelial cells and neutrophils that disrupt the bacterial membrane, leading to pathogen death. We show that NK cells and NKR-expressing T cells constitutively express α-defensins and that KpOmpA and flagellin rapidly induce their release. These data demonstrate for the first time that highly purified NK cells directly recognize and respond to pathogen components through TLRs and evidence defensins as a novel and direct cytotoxic pathway involved in NK cell-mediated protection against microorganisms. (Blood. 2004;104:1778-1783)

Differential distribution of NK cells in decidua basalis compared with decidua parietalis after uncomplicated human term pregnancy

As pregnancy progresses, a characteristic decline in the percentage of CD56 bright CD16 − uterine natural killer (NK) cells occurs. Studies of term decidua, however, have focused only on leukocytes derived from decidua basalis, the site of implantation. The decidua parietalis, lining the remainder of the uterine cavity is another important region of the maternal-fetal interface that forms contact with fetal tissue at the end of the first trimester. The aim of this study was to evaluate possible differences in expression of CD16 and CD56 on leukocytes from normal term decidua basalis and decidua parietalis. Decidua basalis and parietalis samples were obtained from 30 placentas collected after elective cesarean section. Percentages of leukocyte subpopulations and NK cell subsets within the CD45 + cell fraction were determined by flow cytometry. In six decidual samples, concurrent immunohistochemical staining was performed. Higher percentages of CD56 dim CD16 + NK cells and CD56 − CD16 + cells were found in decidua basalis in comparison to decidua parietalis. In contrast, the percentage of CD56 bright CD16 − uterine NK cells was significantly higher in decidua parietalis. Immunohistochemical quantification supported flow cytometric results. We conclude that significant differences exist with respect to the distribution of NK cells in term decidua basalis and parietalis. Future functional studies may improve our understanding of their role at the maternal-fetal interface.

Selective reduction of natural killer cells and T cells expressing inhibitory receptors for MHC class I in the livers of patients with hepatic malignancy.

Natural killer (NK) and CD56(+) T cells are thought to play a central role in antitumour immunity. Their cytolytic activities are controlled by a variety of receptors including CD94 and killer immunoglobulin-like receptors (KIR), which bind to major histocompatibility complex (MHC) class I molecules on target cells and mediate cell activation or inhibition. We have examined the numbers, phenotypes and antitumour cytotoxic functions of hepatic NK and CD56(+) T cells isolated from 22 patients with hepatic malignancy and 19 healthy donors. Flow cytometry revealed that NK cell numbers were increased among hepatic mononuclear cells in malignancy compared to histologically normal livers (mean: 38% vs 27%; P=0.03), but CD56(+) T cell numbers were not (28% vs 27%). NK cells and CD56(+) T cells from tumour-bearing livers exhibited lymphokine-activated killing of K562 targets and T cell receptor-mediated lysis of P815 cells. The expression of CD94 and the KIR isotypes CD158a, CD158b and KIR3DL1 by CD56(+) T cells and NK cells was significantly and consistently reduced in tumour-bearing livers compared to healthy livers ( P<0.05 in all cases). Simultaneous ligation of CD158a, CD158b and KIR3DL1 caused an overall partial inhibition of CD56(+) T cell cytotoxic activity, suggesting that the observed reductions in KIR(+) cell numbers in malignancy are likely to lead to enhanced cytotoxicity. Our results suggest that, while hepatic CD56(+) T cells are not expanded in malignancy, downregulation of KIR and CD94 expression may be a mechanism by which the hepatic immune system can be activated to facilitate tumour rejection.

Elevated substance P levels in HIV-infected men.

The neuropeptide, substance P, is a potent modulator of neuroimmunoregulation. Substance P and its receptor modulate HIV infection. HIV-seropositive men had significantly higher plasma substance P levels compared with uninfected controls, which were associated with decreased CD16 and CD56 natural killer (NK) cell populations. The changes in plasma substance P levels and decreases in NK subsets did not correlate with CD4 cell levels, but a diurnal pattern was suggested for substance P. The balance between substance P expression and functions of immune cells may be important in the immunopathogenesis of HIV infection.

Self‐hypnosis and exam stress: comparing immune and relaxation‐related imagery for influences on immunity, health and mood

AbstractThe effects of self‐hypnosis training on immune function, mood and health at exam time in medical schools were examined, comparing instructions of enhanced immune function with relaxation, whereas instructions of increased energy, alterness, concentration and happiness were common to both procedures. Training consisted of three weekly group sessions, with unrestricted home practice with an audiocassette. Immune assays involved CD3, CD4, CD8, CD19 lymphocytes, CD56 natural killer (NK) cells and blood cortisol. Students receiving immune‐related imagery reported fewer viral illnesses, such as colds and influenza, during the exam period. Immune‐related imagery was also more successful than relaxation imagery in buffering decline in total lymphocytes and subsets. Independent of instructions, hypnosis buffered the decline in CD8 cytotoxic T‐cells observed in control subjects, an effect associated with hypnotic susceptibility (Harvard group scale). Evidence of a buffering effect on NK cells could not be replicated, which may have been confounded by generalized stressors. As found previously, dissociations between negative mood and raised cortisol followed hypnosis training. These findings along with a contemporaneous one with patients with herpes—preliminary due to the small scale of the study—demonstrate for the first time that there are benefits for reported illness as a result of a psychological intervention shown to strengthen the immune system and improve well‐being. The benefits of self‐hypnosis encourage investment in large‐scale illness prevention studies and controlled clinical applications. Copyright © 2001 British Society of Experimental and Clinical Hypnosis

Down-regulation of natural killer cells and of gamma/delta T cells in systemic lupus erythematosus. Does it correlate to autoimmunity and to laboratory indices of disease activity?

A depletion of natural killer (NK) cells seems to play a role in the course of systemic lupus erythematosus (SLE) whereas the possible involvement in this disease of T cell receptor (TCR) gamma/delta positive T cells is still debated. The aim of this study was to evaluate the peripheral blood mononuclear cells (PBMCs) that express NK surface markers CD16 and CD56 or gamma/delta TCR antigen in 58 SLE patients, investigating the possible role of these cell subsets involved in non-MHC-restricted cytotoxicity and their relationship with the main clinical and laboratory parameters. SLE patients had, with respect to controls, considerably decreased values of NK cells (P<0.0004 in percentage and P<0.00004 as absolute number), of non-MHC-restricted T cytotoxic lymphocytes (P<0.007 and P<0.0015, respectively) and of T cells expressing gamma/delta TCR (P<0.02 and P<0.004, respectively). The absolute numbers of these cell subsets positively correlated to each other (P<0.009). gamma/delta T cells inversely correlated with higher ESR values, both percentually (P<0. 006; r=-0.367) and in absolute number (P<0.009; r=-0.350). Moreover, the percentage values of this cell subset inversely correlated with higher levels of CRP (P<0.05; r=-0.256) while SLE patients with anti-SSB/La antibodies had lower values of T lymphocytes bearing gamma/delta TCR, both as percentage (P<0.008) and as absolute number (P<0.02). Our study indicates that non-MHC-restricted cytotoxicity, shared by NK, NK-like and gamma/delta T cells, may be down-regulated in SLE patients, owing to a significant reduction of these PBMC subsets. These specific cell subset impairments seem to affect only some aspects of the disease, suggesting a weakening of the regulatory properties of these cells in the control of different immunological and inflammatory features of SLE, that could be of importance in its clinical expression.

Depression and immunity: clinical factors and therapeutic course

While many reports describe associations between depressive disorders and altered immunity, findings have not been fully consistent. Diagnostic subtype, demographic factors such as age and gender, medical characteristics, and the immune measures selected for assessment may have contributed to the heterogeneous findings. In a study of 21 medically healthy young adults with major depression, we found, consistent with previous reports, evidence of increased lymphocyte activation to mitogen challenge and decreased natural killer (NK) cell numbers and function during acute depression. Fifteen subjects were followed longitudinally. T, CD4 +, CD29 +, and CD45RA + lymphocytes and T-cell mitogen responses decreased significantly ( P < 0.05) during 6 weeks of pharmacotherapy and concurrent clinical improvement. There was no change in NK activity or CD56 + cells. The longitudinal effects appeared unrelated to tricyclic antidepressant levels. Changes in the immune system with short-term clinical improvement in depressed patients are not uniform providing further evidence that several mechanisms are involved in the altered immunity associated with clinical depression.

Expression of lymphocyte subpopulations, cytokine serum levels and blood and urine trace elements in nickel sensitised women

In this study, 20 non-allergic and 20 non-atopic women sensitised only to nickel (Ni) showed similar levels of urine and serum Ni and serum chromium (Cr). On the contrary, serum copper, a marker of inflammation, was significantly higher in the Ni-sensitised group. Sensitised women also had higher values of blood B CD19+, CD5--CD19+ and B and natural killer CD3--CD25+ lymphocytes, but not alterations of some other lymphocyte subsets and serum cytokines. Urine Ni was correlated with “memory” CD4+-CD45RO+ lymphocytes in the non-allergic women and with T CD4+-CD45RO+ and CD3+-CD25+ cells in the atopic women; these subjects also showed a statistically significant correlation of serum Ni with B CD5+-CD19+ lymphocytes and serum IL-13. Moreover, serum Cr of both groups of women was positively or negatively correlated with activated HLA-DR+ cells and/or serum IL-5 and interferon γ. These results (confirming in part those of a previous study on non-allergic men) suggest that both Ni and Cr are involved in mechanisms regulating the immune response and that allergy to these metals could be considered an alteration of their physiological role.

Selective CD4+ T-cell depletion does not prevent graft-versus-host disease.

Donor-derived CD4+ T cells may play a role in the development of graft-versus-host disease (GVHD) and graft-versus-leukemia reaction after allogeneic bone marrow transplantation (BMT). Therefore, we evaluated the effect of CD4+ T-cell depletion on GVHD and graft-versus-leukemia reaction after HLA-matched BMT. CD4 depletion was performed using anti-CD4 monoclonal antibodies and immunomagnetic beads, initially in small-scale experiments on bone marrow and granulocyte colony-stimulating factor-mobilized peripheral blood apheresis products. The result was elimination of the CD4+ T cells from both sources (0% and 2+/-1.4% CD4+ cells, respectively). Subsequently, we used this technique for large-scale negative selection of CD4+ T cells from bone marrow grafts of four consenting leukemic patients in relapse (ALL-3, ANLL-1) (M-3, F-1). The large-scale CD4+ T-cell depletion resulted in >98% (n=4) elimination of CD4+ cells. The resulting population included 17.7+/-4.6% CD3+ T cells, 8.9+/-2.5% CD8+ T cells, 0.1+/-0.1% CD16+ natural killer cells, and 2.3+/-3.2% CD34+ hematopoietic progenitor cells. Patients were transplanted with 2.84+/-1.31 x 10(8) viable cells/kg. They received cyclosporine starting on day -1 as GVHD prophylaxis. Engraftment was fast with a white blood cell count of >1 x 10(9)/L on day 13.2+/-0.5, an absolute neutrophil count of >0.5 x 10(9)/L on day 13.8+/-0.5, and a platelet count of >25 x 10(9)/L on day 26.5+/-6.8. Immunological reconstitution was normal, and peripheral blood phenotyping 3 weeks after BMT disclosed 49.0+/-5.0% CD3, 14.3+/-12.4% CD4, and 59.5+/-7.8% CD8 T cells in addition to 17.0+/-3.0% CD16+ and 9.0+/-3.0% CD56 natural killer cells. Three out of four patients developed very early grade IV GVHD beginning on day 12 (10-13) and died 2-4 months after BMT. One patient is alive and well with a follow-up of 36 months. We conclude that selective CD4 T-cell depletion does not prevent GVHD.

Repopulation of circulating T, B and NK lymphocytes following bone marrow and blood stem cell transplantation.

A variety of T, B and natural killer (NK) cell subsets defined by surface markers were analyzed by double immunofluorescence flow cytometry in the peripheral blood of patients following autologous bone marrow transplantation (ABMT, n = 14), autologous peripheral blood stem cell transplantation (PBSCT, n = 10) and allogeneic bone marrow transplantation (allo-BMT, n = 6). Patients following ABMT were divided in 2 groups, those who did not received G-CSF post-transplant (ABMT, n = 6) and those who did (ABMT + G, n = 8). All patients following PBSCT or allo BMT received G-CSF. In all the groups prolonged significant decreases with respect to normal numbers were observed for the T CD3+, CD2+ and CD25+ subsets, more profound for the CD4+ subset but less for the CD8+ subset, especially following PBSCT (only decreased at 1 month). A significant expansion of the CD3+CD57+ and CD8+CD57+ phenotypes was noticed between 9 and 12 months following ABMT, the group of longer follow-up. Long-lasting expansion of the NK-like CD3+CD56+ and CD3+CD16+ subsets was also observed. The B CD19+ and CD20+ subsets had a significant overexpression from 4 months after ABMT, showing a normally balanced Igk+:Ig1+ ratio. Concordantly, the HLA-DR+ and HLA-DQ+ subsets showed significant increases. The NK CD56+ and CD16+ subsets had a faster recovery than the T or B subsets in all the groups. However, the CD3-CD56+, CD3-CD16+, CD16+CD56+, CD3-CD8+, and especially the CD3-CD57+, CD16+CD57+, and CD56+CD57+ subsets had a slower recovery than the global CD56+, CD16+, or CD57+ subsets. The biological and clinical implications of these findings are discussed.

CD56bright natural killer cell subsets: characterization of distinct functional responses to interleukin-2 and the c-kit ligand.

Natural killer (NK) cells are bone marrow-derived large granular lymphocytes that express the CD56 surface antigen. The CD56bright NK subset represents approximately 10% of all NK cells and is thought to be the least differentiated NK cell component in blood. The most mature NK cell expresses CD56 at low density and CD16 (FcR gammaIII) at high density, whereas CD56bright NK cells either lack CD16 (CD56bright CD16-) or express it at low density (CD56bright CD16dim). c-kit is a tyrosine kinase receptor which is expressed on both CD34+ hematopoietic precursor cells and CD56bright NK cells. In the current study, we characterize interleukin (IL)-2 receptor (IL-2R) and c-kit expression in each of the CD56bright subsets. Both the CD56bright CD16- and CD56bright CD16dim NK subsets express the high-affinity IL-2R and the c-kit receptor when isolated from fresh blood. However, each CD56bright NK cell subset has distinct functional responses to IL-2, the c-kit ligand (KL), or both. Activation of the high-affinity IL-2R on CD56bright CD16- NK cells induces a proliferative response that is significantly weaker than that observed in the CD56bright CD16dim NK cell subset. Incubation of the CD56bright CD16 NK cell subset with KL significantly enhances IL-2-induced proliferation, while KL has no such effect on the CD56bright CD16dim NK subset. Activation of the high-affinity IL-2R in both CD56bright subsets induces lymphokine-activated killer (LAK) activity, but the addition of KL has no effect on LAK activity. Co-stimulation of either CD56bright subset with IL-12 and concentrations of IL-2 that only saturate the high-affinity IL-2R induces substantial interferon (IFN)-gamma production. The addition of KL to this co-stimulatory signal enhances IFN-gamma production in both CD56bright NK subsets. The distinct functional responses to IL-2 and KL seen in the CD56bright CD16- and CD56bright CD16dim NK subsets provide insight into IL-2R signaling and suggest that each phenotype identifies a discrete stage of NK cell differentiation.

CD3- Large Granular Lymphocytes Recognize a Heat-Inducible Immunogenic Determinant Associated With the 72-kD Heat Shock Protein on Human Sarcoma Cells

Traditionally, heat shock proteins (HSPs) are believed to be located intracellularly, where they perform a variety of chaperoning functions. Recently, evidence has accumulated that some tumor cells express HSPs on the cell surface. The present study confirms this finding and correlates HSP72 cell surface expression, induced by nonlethal heat shock, with an increased sensitivity to interleukin-2-stimulated CD3-natural killer (NK) cells. After nonlethal heat shock, a monoclonal antibody directed against the major heat-inducible 72-kD HSP (HSP72) stains the cell surface of sarcoma cells (ie, Ewing's sarcoma cells or osteosarcoma cells) but not that of normal cells (ie, peripheral blood lymphocytes, fibroblasts, phytohemagglutin-stimulated blasts, B-lymphoblastoid cell lines) or of mammary carcinoma cell line MX-1 carcinoma cells. In this study, we show for the first time a correlation of HSP72 cell surface expression with an increased susceptibility to lysis by NK effector cells. This finding is supported by the following points: (1) HLA-disparate effector cells show similar, elevated lysis of HSP72+ heat-treated sarcoma cells; (2) CD(3-) NK cells, but not CD3+ cytotoxic T lymphocytes, are responsible for the recognition of heat-shocked sarcoma cells; (3) by antibody-blocking studies, an immunogenic HSP72 determinant, which is expressed selectively on the cell surface of heat-treated sarcoma cells could be correlated with NK recognition; (4) the reported phenomenon is independent of a heat-induced, transient downregulation of major histocompatibility complex (MHC) class-I expression; and (5) blocking of MHC class-I-restricted recognition, using either MHC class-I-specific monoclonal antibody W6/32 on the target cells or alpha/beta T-cell receptor monoclonal antibody WT31 on effector cells, also has no inhibitory effect on the lysis of HSP72+ tumor cells. Finally, our in vitro data might have further clinical implications with respect to HSP72 as a stress-inducible, sarcoma-specific NK recognition structure.

BY55 monoclonal antibody delineates within human cord blood and bone marrow lymphocytes distinct cell subsets mediating cytotoxic activity.

We had previously reported, using BY55 monoclonal antibody, a cell surface 80-kDa protein restricted to human functional peripheral blood cytotoxic lymphocytes with either natural killer CD3- or cytotoxic T lymphocyte CD3+CD8+ phenotype. In the present report, we studied the cytotoxic lymphocytes in adult bone marrow and newborn cord blood as these organs are commonly used as sources of hematological stem cells for allogeneic transplantation. Our results showed that BY55 mAb labeled only 5-10% of the bone marrow lymphocytes, which included a major proportion of CD3+ CD8+ cytotoxic T lymphocytes. Interestingly, within cord blood cells, BY55+ lymphocytes represented 20-35% of the lymphocytes corresponding exclusively to a CD3- cell subset. Furthermore, we detected in cord blood no cytotoxic T lymphocyte activity but we demonstrated that the CD3-BY55+ cell subset contained the whole natural killer activity.

Immunogenicity of recombinant human interleukin-2: biological features and clinical relevance.

The immunogenicity of recombinant interleukin-2 (rIL-2, EuroCetus, Amsterdam, Netherlands) was studied in seventy-six patients receiving different subcutaneous immunotherapy regimens. Patients presented with progressive metastatic renal cell carcinoma, malignant melanoma, colorectal cancer, B-cell lymphoma, and Hodgkin's disease. An enzyme immunoassay (EIA) was employed to screen patients for development of non-neutralizing antibodies against rIL-2, antibody specificity was confirmed by a standard Western blot. Neutralizing serum activity against rIL-2 was detected using a standard CTLL mouse proliferation assay. Additionally, serum levels of soluble interleukin-2 receptors and lymphocyte subsets expressing the CD56 natural killer (NK) associated antigen were measured. In a proportion of approximately 35% to 90% of the patients treated, non-neutralizing antibodies against rIL-2 could be detected after all treatment courses were evaluated. Antibodies were of the IgG, IgM, IgA and IgD subtypes. None of the 76 patients exhibited serum neutralizing activity after one treatment course. Five patients exhibited neutralizing anti-rIL-2 serum activity after two or more treatment courses of systemic rIL-2. In three of these patients, antibodies neutralized both recombinant and natural IL-2. Patients developing neutralizing anti-rIL-2 antibodies, exhibited significantly lower serum sIL-2 receptor levels upon the emergence of serum neutralizing activity than patients without antibody. Additionally, NK cell associated CD56 positivity was significantly lower in patients who exhibited neutralizing anti-rIL-2 serum activity than in patients who did not. A significant decrease in levels of soluble IL-2 receptors and CD56 NK cell positivity was observed, when comparing values prior to and after onset of serum neutralizing activity against rIL-2. However, while emergence of neutralizing antibodies to rIL-2 diminished rIL-2 induced biological activation, it did not coincide with abrogation of treatment response.

Severe chronic autoimmune thrombocytopenic purpura is associated with an expansion of CD56+ CD3- natural killer cells subset [see comments

Recent studies have indicated that autoimmune thrombocytopenic purpura (ATP) patients show immune system alterations that are not restricted to the B-cell compartment, but that also affect T lymphocytes. This report studies the phenotypic characteristics of natural killer (NK) cells in the peripheral blood of ATP patients, as well as their clinical significance in 33 ATP patients with active disease. Ten patients had stable disease (sustained platelet counts > 50,000/microL without the need for treatment), whereas 23 patients had therapy-dependent disease (platelet counts < 50,000/microL). A significant increase in both CD56+ CD3- NK cells and CD56+ CD3+ cytotoxic T lymphocytes was observed in peripheral blood mononuclear cells and in purified CD2+ cells from therapy-dependent ATP patients as compared with ATP patients with stable disease and healthy controls. Moreover, there were more major histocompatibility complex (MHC) class II molecules in the CD56+ CD3- cells from the therapy-dependent patients' peripheral blood preparations than there were in the stable ATP patients' and healthy controls' peripheral blood preparations. This growth in the number of CD56+ CD3- NK cells was statistically higher in patients whose disease was refractory to conventional therapy (corticosteroids and splenectomy). In addition to the CD56+ CD3- NK cells, the percentage of CD3+ T lymphocytes and their proliferative response to phytohemagglutinin (PHA) stimulation were studied in fresh CD2+ preparations from nine patients with stable disease, 22 patients with therapy-dependent disease, and 26 healthy controls. The proliferative response of CD2+ lymphocytes from both groups was similar and significantly defective with respect to that found in healthy controls. In conclusion, clinically severe ATP (therapy-dependent disease) is associated with a significant increase of CD56+ CD3- NK cells, which is particularly marked in patients whose disease is refractory to therapy.

Severe Chronic Autoimmune Thrombocytopenic Purpura Is Associated With an Expansion of CD56 + CD3− Natural Killer Cells Subset

AbstractRecent studies have indicated that autoimmune thrombocytopenic purpura (ATP) patients show immune system alterations that are not restricted to the B-cell compartment, but that also affect T lymphocytes. This report studies the phenotypic characteristics of natural killer (NK) cells in the peripheral blood of ATP patients, as well as their clinical significance in 33 ATP patients with active disease. Ten patients had stable disease (sustained platelet counts > 50,000/μL without the need for treatment), whereas 23 patients had therapy-dependent disease (platelet counts < 50,000/μL). A significant increase in both CD56+CD3−NK cells and CD56+CD3+ cytotoxic T lymphocytes was observed in peripheral blood mononuclear cells and in purified CD2+ cells from therapy-dependent ATP patients as compared with ATP patients with stable disease and healthy controls. Moreover, there were more major histocompatibility complex (MHC) class II molecules in the CD56+ CD3− cells from the therapy-dependent patients’ peripheral blood preparations than there were in the stable ATP patients’ and healthy controls’ peripheral blood preparations. This growth in the number of CD56+CD3− NK cells was statistically higher in patients whose disease was refractory to conventional therapy (corticosteroids and splenectomy). In addition to the CD56+CD3− NK cells, the percentage of CD3+ T lymphocytes and their proliferative response to phytohemagglutinin (PHA) stimulation were studied in fresh CD2+ preparations from nine patients with stable disease, 22 patients with therapy-dependent disease, and 26 healthy controls. The proliferative response of CD2+ lymphocytes from both groups was similar and significantly defective with respect to that found in healthy controls. In conclusion, clinically severe ATP (therapy-dependent disease) is associated with a significant increase of CD56+ CD3− NK cells, which is particularly marked in patients whose disease is refractory to therapy.