Natural killer cells may be the only cells in normal mouse lymphoid cell populations endowed with cytolytic ability for antibody-coated tumour target cells

LINC02126 is a potential diagnostic, prognostic and immunotherapeutic target for lung adenocarcinoma

Background

Adenocarcinoma has long been an independent histological class of lung cancer, which leads to high morbidity and mortality. We aimed to investigate the contribution of LINC02126 in lung adenocarcinoma.

Methods

RNA sequencing data and clinical information were downloaded. Diagnostic efficiency and survival analysis of LINC02126 were performed, followed by functional analysis of genes co-expressed with LINC02126 and differentially expressed genes (DEGs) in different LINC02126 expression groups. Tumor immune microenvironment (TIME) cell infiltration and correlation analysis of tumor mutation burden were performed in different LINC02126 expression groups.

Results

In lung adenocarcinoma, the expression level of LINC02126 was significantly decreased. Significant expression differences of LINC02126 were found in some clinical variables, including T staging, M staging, sex, stage, and EGFR mutation. LINC02126 had potential diagnostic and prognostic value for patients. In the low LINC02126 expression group, the infiltration degree of most immune cells was significantly lower than that in the high LINC02126 expression group. Tumor mutation burden level and frequency of somatic mutation in patients with low LINC02126 expression group were significantly higher than in patients with high LINC02126 expression group.

Conclusions

LINC02126 could be considered as a diagnostic, prognostic and immunotherapeutic target for lung adenocarcinoma.

LRMP Associates With Immune Infiltrates and Acts as a Prognostic Biomarker in Lung Adenocarcinoma

Background: Lymphoid-restricted membrane protein (LRMP) is an endoplasmic reticulum-associated protein that is expressed in a developmentally regulated manner in both B and T cell lineages. However, the role of LRMP in the growth, prognosis and immune infiltration in lung adenocarcinoma (LUAD) remains unclear.

Method: The expression levels of LRMP mRNA in tumor and normal tissues were analyzed using Tumor Immune Estimation Resource 2.0 (TIMER 2.0) and Gene Expression Profiling Interactive Analysis 2 (GEPIA 2). LRMP protein expression was examined using the Human Protein Atlas. In vitro experiments, including qRT-PCR Western blot and immunohistochemistry staining were also performed to investigate LRMP expression. GEPIA2 and Kaplan-Meier plotter databases were used to analyze the clinical prognostic significance of LRMP. To further confirm the underlying function of LRMP, the data were analyzed using gene set enrichment analysis. Moreover, we also constructed plasmids to overexpress LRMP and explored the effect of LRMP in A549 cell line. Additionally, Tumor Immune single-cell Hub was used to investigate the distribution of LRMP in the LUAD immune microenvironment; TIMER and CIBERSORT were used to investigate the relationships among LRMP, LRMP co-expressed genes, and tumor-infiltrating immune cells; Finally, the correlations between LRMP and immune checkpoints were analyzed using TIMER 2.0.

Results: The expression of LRMP was significantly lower in LUAD tissues and cell lines. High LRMP expression is associated with a better prognosis in patients with LUAD. In vitro experimental studies demonstrated that overexpression of LRMP could decrease the proliferation, migration and invasion in A549 cells, and downregulated multiple oncogenic signaling pathways, including p-STAT3, p-PI3K-p-AKT, p-MEK and EMT pathways. GSEA results showed that immuno-related and cell adhesion pathways were enriched in samples with high LRMP expression. LRMP and its co-expressed genes were positively correlated with various tumor-infiltrating immune cells and their markers. Additionally, LRMP positively correlated with immune checkpoints.

Conclusions: Our data suggest that LRMP may act as a tumor suppressor gene and indicates a better prognosis. Moreover, LRMP is associated with immune infiltrates which may be involved in immunotherapy response in LUAD. Further studies are needed to validate these findings.

Transcriptional Regulation of Natural Killer Cell Development and Functions

Natural killer (NK) cells are the major lymphocyte subset of the innate immune system. Their ability to mediate anti-tumor cytotoxicity and produce cytokines is well-established. However, the molecular mechanisms associated with the development of human or murine NK cells are not fully understood. Knowledge is being gained about the environmental cues, the receptors that sense the cues, signaling pathways, and the transcriptional programs responsible for the development of NK cells. Specifically, a complex network of transcription factors (TFs) following microenvironmental stimuli coordinate the development and maturation of NK cells. Multiple TFs are involved in the development of NK cells in a stage-specific manner. In this review, we summarize the recent advances in the understandings of TFs involved in the regulation of NK cell development, maturation, and effector function, in the aspects of their mechanisms, potential targets, and functions.

Regulation of Murine Natural Killer Cell Development

Natural killer (NK) cells are effector lymphocytes of the innate immune system that are known for their ability to kill transformed and virus-infected cells. NK cells originate from hematopoietic stem cells in the bone marrow, and studies on mouse models have revealed that NK cell development is a complex, yet tightly regulated process, which is dependent on both intrinsic and extrinsic factors. The development of NK cells can be broadly categorized into two phases: lineage commitment and maturation. Efforts to better define the developmental framework of NK cells have led to the identification of several murine NK progenitor populations and mature NK cell subsets, each defined by a varied set of cell surface markers. Nevertheless, the relationship between some of these NK cell subsets remains to be determined. The classical approach to studying both NK cell development and function is to identify the transcription factors involved and elucidate the mechanistic action of each transcription factor. In this regard, recent studies have provided further insight into the mechanisms by which transcription factors, such as ID2, FOXO1, Kruppel-like factor 2, and GATA-binding protein 3 regulate various aspects of NK cell biology. It is also becoming evident that the biology of NK cells is not only transcriptionally regulated but also determined by epigenetic alterations and posttranscriptional regulation of gene expression by microRNAs. This review summarizes recent progress made in NK development, focusing primarily on transcriptional regulators and their mechanistic actions.

How immunoglobulin G antibodies kill target cells: revisiting an old paradigm

The capacity of immunoglobulin G (IgG) antibodies to eliminate virtually any target cell has resulted in the widespread introduction of cytotoxic antibodies into the clinic in settings of cancer therapy, autoimmunity, and transplantation, for example. More recently, it has become apparent that also the protection from viral infection via IgG antibodies may require cytotoxic effector functions, suggesting that antibody-dependent cellular cytotoxicity (ADCC) directed against malignant or virally infected cells is one of the most essential effector mechanisms triggered by IgG antibodies to protect the host. A detailed understanding of the underlying molecular and cellular pathways is critical, therefore, to make full use of this antibody effector function. Several studies over the last years have provided novel insights into the effector pathways and innate immune effector cells responsible for ADCC reactions. One of the most notable outcomes of many of these reports is that cells of the mononuclear phagocytic system rather than natural killer cells are critical for removal of IgG opsonized target cells in vivo.

Infectious Diseases: Need for Targeted Drug Delivery

Infectious diseases are a leading cause of death worldwide, with the constant fear of global epidemics. It is indeed an irony that the reticuloendothelial system (RES), the body’s major defence system, is the primary site for intracellular infections which are more difficult to treat. Pro-inflammatory M1 macrophages play an important role in defence. However, ingenious pathogen survival mechanisms including phagolysosome destruction enable their persistence. Microbial biofilms present additional challenges. Low intracellular drug concentrations, drug efflux by efflux pumps and/or enzymatic degradation, emergence of multi-drug resistance (MDR), are serious limitations of conventional therapy. Targeted delivery using nanocarriers, and passive and active targeting strategies could provide quantum increase in intracellular drug concentration. Receptor mediated endocytosis using appropriate ligands is a viable approach. Liposomes and polymeric/lipidic nanoparticles, dendrimers micelles and micro/nanoemulsions could all be relied upon. Specialised targeting approaches are demonstrated for important diseases like tuberculosis, HIV and Malaria. Application of targeted delivery in the treatment of veterinary infections is exemplified and future possibilities indicated. The chapter thus provides an overview on important aspects of infectious diseases and the challenges therein, while stressing on the promise of targeted drug delivery in augmenting therapy of infectious diseases.

Natural killer (NK) cells in antibacterial innate immunity: angels or devils?

Natural killer (NK) cells were first described as immune leukocytes that could kill tumor cells and soon after were reported to kill virus-infected cells. In the mid-1980s, 10 years after their discovery, NK cells were also demonstrated to contribute to the fight against bacterial infection, particularly because of crosstalk with other leukocytes. A wide variety of immune cells are now recognized to interact with NK cells through the production of cytokines such as interleukin (IL)-2, IL-12, IL-15 and IL-18, which boost NK cell activities. The recent demonstration that NK cells express pattern recognition receptors, namely Toll-like and nucleotide oligomerization domain (NOD)-like receptors, led to the understanding that these cells are not only under the control of accessory cells, but can be directly involved in the antibacterial response thanks to their capacity to recognize pathogen-associated molecular patterns. Interferon (IFN)-γ is the predominant cytokine produced by activated NK cells. IFN-γ is a key contributor to antibacterial immune defense. However, in synergy with other inflammatory cytokines, IFN-γ can also lead to deleterious effects similar to those observed during sepsis. Accordingly, as the main source of IFN-γ in the early phase of infection, NK cells display both beneficial and deleterious effects, depending on the circumstances.

Inositol phospholipid signaling and the biology of natural killer cells

A family of phosphoinositide-3 kinase (PI3K) isoenzymes catalyzes the production of second messengers that recruit critical regulators of cell growth, survival, proliferation and motility. Conversely, 3'-(phosphatase and tensin homolog) and 5'-inositol polyphosphatases (SH2-containing inositol phosphatases 1/2, SHIP1/2) are recruited to sites of PI3K signaling at the plasma membrane to oppose or, in some cases, to modify and enhance PI3K signaling. A substantial and growing body of literature demonstrates that these enzymes which mediate interchange of phosphates on inositol phospholipid species at the plasma membrane have prominent roles in natural killer cell biology, including development, effector functions and trafficking. Here, we review the salient points of these recent papers with a special emphasis on the role of p110δ and SHIP1 in natural killer cells.

A standardized conversion of IgG antibody to bispecific form with inversely altered affinities for Fcγ-receptors II and III

This work aims to enhance killing of antibody-coated human tumor cells by altering the antibody's affinity for two effector-cell Fcγ-receptors (FcγR). Affinity for the activating FcγRIII is raised, affinity for the inhibitory FcγRIIB is reduced, with the ratio between the two association constants increasing >1000-fold. We use as a standard tool the Fab'γ from a monoclonal antibody specific for human FcγRIII. This Fab'γ module is bonded to an IgG antibody by a tandem thioether link running between cysteine residues in the hinge vicinity of each protein, thus forming a bispecific FabIgG construct. Simultaneously, effector function of the IgG module is adjusted by leaving its hinge open and adding negative charges. FabIgG constructs derived from the chimeric IgG1 antibody rituximab show the following properties. (1) The titer for antibody-dependent cellular cytotoxicity is enhanced by 12-100-fold, reflecting the affinity of the Fab'γ module for effector-cell FcγRIII. (2) Two functions of the construct's Fcγ, activation of complement and prolonged metabolic survival, are moderately reduced. (3) In contrast, affinities of the Fcγ for all FcγR are severely reduced, with two anticipated consequences. First, attacks by macrophages on antibody-coated cells are favored by reduced engagement of the inhibitory FcγRIIB. Second, reduced engagement of activating FcγR by the Fcγ lowers the probability of untoward crosslinkings of FcγR, which have been shown to provoke toxicity. If the Fab'γ module possesses human constant regions, the linkage strategy requires prior genetic deletion of at least one cysteine residue. With both Fab'γ and IgG modules available, FabIgG can be prepared in 35 h.

CD38 as a therapeutic target

The CD38 molecule is well represented on cell surfaces in many cases of a variety of lymphoid tumors, notably multiple myeloma, AIDS-associated lymphomas, and post-transplant lymphoproliferations. As such, this molecule is a promising target for antibody therapy. After early disappointments, improved anti-CD38 antibodies of strong cytolytic potential have been described by 3 groups. First, a human IgG monoclonal anti-CD38 antibody raised in mice transgenic for human Ig has been found to induce potent complement and cellular cytotoxicities against both myeloma cell lines and fresh harvests from myeloma marrow and leukemic blood. This antibody also exhibits the singular property of inhibiting the CD38 cyclase activity. Second, a series of CD38-specific human antibodies, with high affinities and high ADCC activities against cell lines and primary cultures of myeloma, has been selected from a unique phage-display library. Finally, to enhance specificity for myeloma cells, bispecific domain antibodies targeting both CD38 and CD138 have been developed. As they lack any Fc module, these constructs rely on cytotoxicity for delivering a toxin to tumor cells. The list of candidate CD38-bearing neoplasms as targets for these antibody constructs can now be expanded to include acute promyelocytic leukemia, and possibly other myeloid leukemias, in which surface CD38 can be induced by retinoid treatment. One caveat here is that evidence has been produced to suggest that CD38 promotes pulmonary manifestations of the hazardous retinoic acid syndrome.

CD38 as a therapeutic target

The CD38 molecule is well represented on cell surfaces in many cases of a variety of lymphoid tumors, notably multiple myeloma, AIDS-associated lymphomas, and post-transplant lymphoproliferations. As such, this molecule is a promising target for antibody therapy. After early disappointments, improved anti-CD38 antibodies of strong cytolytic potential have been described by 3 groups. First, a human IgG monoclonal anti-CD38 antibody raised in mice transgenic for human Ig has been found to induce potent complement and cellular cytotoxicities against both myeloma cell lines and fresh harvests from myeloma marrow and leukemic blood. This antibody also exhibits the singular property of inhibiting the CD38 cyclase activity. Second, a series of CD38-specific human antibodies, with high affinities and high ADCC activities against cell lines and primary cultures of myeloma, has been selected from a unique phage-display library. Finally, to enhance specificity for myeloma cells, bispecific domain antibodies targeting both CD38 and CD138 have been developed. As they lack any Fc module, these constructs rely on cytotoxicity for delivering a toxin to tumor cells. The list of candidate CD38-bearing neoplasms as targets for these antibody constructs can now be expanded to include acute promyelocytic leukemia, and possibly other myeloid leukemias, in which surface CD38 can be induced by retinoid treatment. One caveat here is that evidence has been produced to suggest that CD38 promotes pulmonary manifestations of the hazardous retinoic acid syndrome.

Soluble CD14 receptor expression and monocyte heterogeneity but not the C-260T CD14 genotype are associated with severe acute pancreatitis

OBJECTIVE

Soluble CD14 is derived from a membrane glycoprotein, and it enhances endothelial cytokine responses to lipopolysaccharide. We studied the role of soluble CD14 in the pathogenesis of the systemic inflammatory response associated with acute pancreatitis, to determine whether altered expression was due to a functional C-260T polymorphism in the CD14 promoter gene or altered monocyte heterogeneity.

DESIGN

Prospective case-matched study.

SETTING

Tertiary pancreatic treatment unit in the United Kingdom.

SUBJECTS

Patients with pancreatitis and controls.

INTERVENTIONS

DNA from 117 patients with pancreatitis (34 severe) and 263 controls underwent CD14 genotyping using restriction fragment length polymorphism-polymerase chain reaction.

MEASUREMENTS AND MAIN RESULTS

Peripheral venous blood samples at 24 and 72 hrs after the onset of abdominal pain were analyzed for sCD14 levels. Isolated peripheral blood mononuclear cells were phenotyped for CD14/CD16 receptor expression using immunofluorescence flow cytometry. Disease severity was assessed using Atlanta criteria, Acute Physiology Scores, and C-reactive protein.Soluble CD14 levels were higher in severe (24-hr median, 66.6 ng/mL; 72-hr median, 72.2 ng/mL) compared with mild attacks (24-hr median, 50.7 ng/mL; 72-hr median, 49.7 ng/mL, p < .001), although the latter was similar to controls (median, 51 ng/mL). Furthermore, soluble CD14 levels correlated with Acute Physiology Scores (p < .001) and C-reactive protein (p = .01).Peripheral blood mononuclear cells CD14++ (p = .008), CD14+/16+ (p = .003), and CD16++ (p = .015) receptor densities were all increased in severe attacks at 24 hrs. Early CD14+/16+ receptor density correlated with sCD14 (p < .001), Acute Physiology Scores (p < .001), and C-reactive protein (p = 0.006). The CD14 genotype prevalence in acute pancreatitis was similar to controls and failed to correlate with any variables studied.

CONCLUSIONS

Increased soluble CD14 expression is associated with the systemic inflammatory response to acute pancreatitis and an expansion of the proinflammatory CD14+/CD16+ monocyte subset. Its targeted disruption may afford some benefit in preventing the development of systemic complications.

Spontaneous cell-mediated cytotoxicity (SCMC) in various mammalian species and chickens: selective reaction pattern and different mechanisms

Cultured cell lines derived from donors of various species served as 75Se- or 51Cr-labelled targets in microcytotoxicity assays. As in human donors, considerable spontaneous cell-mediated cytotoxicity (SCMC) was exhibited by peripheral blood lymphoid effector cells from healthy chickens, mink, swine, cattle, horses and tigers. Although all target lines tested could be lysed in SCMC, there was no 'general SCMC target' for all species or all individuals of one species. The selectivity, the kinetics, and the strength of SCMC reflected the capacity of the effector cells rather than a 'susceptibility' of the target to lysis. Classical major histocompatibility complex products, determinants specific for distinct cell types or subpopulations, or antigens associated with Epstein-Barr virus, herpes virus ateles, herpes virus papio, or Marek's disease virus were not appreciably involved in SCMC. No 'malignant phenotype' on targets was required for the cytotoxic effect. Yet undefined xenogeneic, allogeneic, and individual structures seem to be involved in SCMC. Depending on their expression, a target can be classified as 'species-related' or as 'individual-related'. Intermediate forms are conceivable. SCMC might comprise different cytotoxic mechanisms. Antibodies are not required for lysis to occur, but serum factors including immunoglobulins can have considerable influence on SCMC.

Alteration of NK- and ADCC-activities in rats genetically selected for low or high platelet serotonin level

By selective breeding we have recently obtained two discrete sublines of rats that differ in serotonin content in their platelets. As both serotonin and platelets may influence, or even take part, in immune reactions, we tested in this work the natural cytotoxicity in rats with constitutionally different platelet serotonin levels (PSL). Rats with low platelet serotonin level (mean +/- SD, 1.26 +/- 0.14 micrograms 5HT/mg protein; 81% vs. controls) had significantly higher (P less than 0.001) natural killer (NK) activity (mean +/- SD, 9.1 +/- 3.9%) than control rats with average PSL (1.57 +/- 0.18 micrograms 5HT/mg protein). On the contrary, rats with constitutionally high PSL (2.42 +/- 0.21 micrograms 5HT/mg protein, 154% vs. controls) had somewhat lower (P less than 0.02) NK activity (4.1 +/- 1.7%) than control animals (5.7 +/- 1.9%). Antibody-dependent cellular cytotoxicity (ADCC) against nucleated targets of the RCH line, detecting lymphoid effectors, as well as ADCC against chicken red blood cells (CRBC), detecting predominantly non-lymphoid effectors, were also significantly higher (P less than 0.001) in rats with low PSL (19.6 +/- 6.8% vs. 6.6 +/- 3.1% in controls for lymphoid effectors, and 71.8 +/- 6.1% vs. 48.7 +/- 8.8% in control rats for non-lymphoid effectors). However, no significant alteration of either ADCC was determined in rats with high PSL. The results suggest in vivo regulation of natural cytotoxicity by serotonin.

Natural killer (NK) cell response to virus infections in mice with severe combined immunodeficiency. The stimulation of NK cells and the NK cell-dependent control of virus infections occur independently of T and B cell function

The activation, proliferation, and antiviral properties of natural killer (NK) cells were examined in severe combined immunodeficiency (SCID) mice to determine the influence of mature T or B cells on virus-induced NK cell functions and to more conclusively determine the antiviral properties of prototypical CD3- NK cells. NK cells were activated to high levels of cytotoxicity 3 d after infection of mice with lymphocytic choriomeningitis virus (LCMV) or murine cytomegalovirus (MCMV). Analyses of spleen leukocytes from LCMV-infected mice by a variety of techniques indicated that the NK cells proliferated and increased in number during infection. Propidium iodide staining of the DNA of cycling cells revealed that the great majority of proliferating spleen leukocytes 3 d after LCMV infection was of the NK cell phenotype (CD3-, Ig-, Mac-1+, CZ1+, 50% Thy-1+), in contrast to uninfected mice, whose proliferating cells were predominantly of other lineages. Analyses of the NK cell responses over a 2 wk period in control CB17 mice infected with MCMV indicated a sharp rise in serum interferon (IFN) and spleen NK cell activity early (days 3-5) in infection, followed by sharp declines at later stages. In SCID mice the IFN levels continued to rise over a 10-d period, whereas the NK cell response peaked on day 3-5 and gradually tapered. In contrast to the immunocompetent CB17 mice, SCID mice did not clear the MCMV infection and eventually succumbed. SCID mice, again in contrast to immunocompetent CB17 mice, also failed to clear infections with LCMV and Pichinde virus (PV); these mice, infected as adults, did not die but instead developed long-term persistent infections. Depletion of the NK cells in vivo with antiserum to asialo GM1 rendered both SCID and CB17 control mice much more sensitive to MCMV infection, as shown by titers of virus in organs and by survival curves. In contrast, similar depletions of NK cells did not enhance the titers of the NK cell-resistant virus, LCMV. Two variants of PV, one sensitive to NK cells and the other selected for resistance to NK cells by in vivo passage, were also tested in NK cell-depleted SCID mice. The NK-sensitive PV replicated to higher titers in NK cell-depleted SCID mice, whereas the titers of the NK cell-resistant PV were the same, whether or not the mice had NK cells. These experiments support the concept that CD3- prototypical NK cells mediate resistance to NK cell-sensitive viruses via a mechanism independent of antiviral or "natural" antibody.(ABSTRACT TRUNCATED AT 400 WORDS)

A novel guanosine analog, 7-thia-8-oxoguanosine, enhances macrophage and lymphocyte antibody-dependent cell-mediated cytotoxicity

Intraperitoneal treatment of mice with a novel guanosine analog, 7-thia-8-oxoguanosine (7-thia-8-oxoGuo), gives rise to activated splenic lymphocytes and peritoneal macrophages with enhanced capacity to mediate antibody-dependent cellular cytotoxicity (ADCC). ADCC activities against both chicken red blood cells and P815 murine plasmacytoma cells were enhanced, indicating that macrophages as well as lymphocytes functioning as K-cells in the two distinct cytolytic systems, were activated by 7-thia-8-oxoGuo. Furthermore, 7-thia-8-oxoGuo enhanced lymphocyte-mediated ADCC activity in beige (bgJ/bgJ) mice against P815, thus indicating the ability of 7-thia-8-oxoGuo to function as a potent immunomodulator even in an animal that is known to possess selective impairment of naturally occurring killer lymphocytes. These results suggest that 7-thia-8-oxoGuo could serve as an agent for immunomodulation and immunorestoration.

Biology of natural killer cells

Studies of cytotoxicity by human lymphocytes revealed not only that both allogeneic and syngeneic tumor cells were lysed in a non-MHC-restricted fashion, but also that lymphocytes from normal donors were often cytotoxic. Lymphocytes from any healthy donor, as well as peripheral blood and spleen lymphocytes from several experimental animals, in the absence of known or deliberate sensitization, were found to be spontaneously cytotoxic in vitro for some normal fresh cells, most cultured cell lines, immature hematopoietic cells, and tumor cells. This type of nonadaptive, non-MHC-restricted cellmediated cytotoxicity was defined as “natural” cytotoxicity, and the effector cells mediating natural cytotoxicity were functionally defined as natural killer (NK) cells. The existence of NK cells has prompted a reinterpretation of both the studies of specific cytotoxicity against spontaneous human tumors and the theory of immune surveillance, at least in its most restrictive interpretation. Unlike cytotoxic T cells, NK cells cannot be demonstrated to have clonally distributed specificity, restriction for MHC products at the target cell surface, or immunological memory. NK cells cannot yet be formally assigned to a single lineage based on the definitive identification of a stem cell, a distinct anatomical location of maturation, or unique genotypic rearrangements.

Characterization of IL-2-induced murine cells which exhibit ADCC activity

The incubation of murine splenocytes in recombinant interleukin 2 (IL-2) gives rise to both lymphokine-activated killer (LAK) cells capable of lysing fresh tumor cells and cells capable of mediating antibody-dependent cellular cytotoxicity (ADCC) in the presence of anti-H2 allosera. A similarity between these two IL-2-induced cell populations was found. The precursors of the cells mediating these activities were shown to be ASGM1 positive, Thy 1 negative, and radiosensitive. Cells taken from the spleen, thymus, and bone marrow were able to mediate ADCC after culture in IL-2. The effector cell was either Thy 1 positive or negative and was less affected by anti-Thy 1 plus C' treatment than cells which mediated LAK activity. In addition ADCC was exhibited in IL-2-cultured splenocytes from various murine strains and correlated with their LAK activity with one exception. While IL-2-cultured C57BL/6 splenocytes exhibited LAK activity similar to that of C3H LAK cells, no ADCC activity could be demonstrated in C57BL/6 cells. Study of the difference in the ability of these two strains to mediate ADCC revealed that IL-2-induced FcR+ cells in C3H thymocytes, but not in C57BL/6 thymocytes. Based on FACS analysis and on the radiosensitivity of the induction of both FcR+ cells and ADCC, it was suggested that IL-2 was expanding a small FcR+ cell population rather than inducing an increase in FcR density on the cell surface. The relationship between the IL-2-induced ADCC mediator and other IL-2-induced cells, as well as ADCC effector cells, and the possible implications of the results for the in vivo therapy of cancer based on ADCC are discussed.

Simultaneous development of antibody-dependent cellular cytotoxicity (ADCC) and natural killer (NK) activity in irradiated mice reconstituted with bone marrow cells

Spleen cells from irradiated, bone marrow-reconstituted mice were tested for their ability to mediate antibody-dependent cellular cytotoxicity against P815 target (ADCC-P815), ADCC against sheep red blood cells (ADCC-SRBC), and natural killer (NK) activity judged as YAC-1 lysis at different times after bone marrow reconstitution. Donor-derived ADCC-P815 effectors were found to appear in the spleens 10-12 days after bone marrow reconstitution simultaneously with the appearance of donor-derived NK cells. NK cells recently derived from bone marrow are known to express the Thy-1 antigen; the phenotype of the "early" ADCC-P815 effectors was found to be the same as that of NK cells, i.e., Thy-1+, asialo-GM1+. These data suggest that ADCC-P815 effector cells belong to the NK cell population. ADCC-SRBC, in contrast to ADCC-P815 and NK activity, was already high on Day 7 after bone marrow reconstitution. However, it was mediated partly by recipient-derived effectors. ADCC-SRBC effectors were characterized to be different from ADCC-P815 effectors.

Activation of mouse peritoneal macrophages by monoclonal antibodies to Mac-1 (complement receptor type 3)

Several features of activation of mouse peritoneal macrophages were elicited by 1-2-d exposure to submicrogram concentrations of anti-Mac-1 (M1/70), a rat monoclonal antibody that reacts with the alpha chain of complement receptor type 3 (Mac-1). The changes induced included enhanced capacity to secrete H2O2 when triggered with PMA, decreased secretion of proteins, increased expression of Ia antigen and decreased phagocytosis of particles. These changes closely resembled those induced by rIFN-gamma in type, extent, and time course. The concentration of M1/70 IgG resulting in 50% of the maximal activation of macrophage H2O2-releasing capacity averaged 0.18 +/- 0.03 micrograms/ml. This activation was not blocked by anti-FcR mAb, and could be reproduced with M18/2, a mAb against beta chain of Mac-1, suggesting that a direct ligation of Mac-1 with mAb was responsible for the activation. Neither depletion of T cells nor addition of neutralizing Abs to IFN-gamma or TNF-alpha prevented M1/70-mediated macrophage activation. Moreover, F(ab')2 of M1/70, or plating of macrophages on C3bi-coated surfaces, inhibited the activation of macrophages by rIFN-gamma. These findings suggest that Mac-1 (CR3) may play an important role in macrophage activation.

Asymmetrical involvement of the cerebral neocortex on the response to an immunopotentiator, sodium diethyldithiocarbamate

We have previously shown that the neocortex in mice has a lateralized influence on the immune system. A partial left or bilateral neocortical lesion selectively decreases spleen T-cell numbers and function, natural killer and (NK) activity, but a right neocortical lesion do not affect NK activity, and increases T-cell numbers and T-cell-mediated events. Here we report that the immunopotentiating activity of sodium diethyldithiocarbamate (Imuthiol), a compound that selectively increases T-cell numbers and activities, is dependent on an intact neocortex. The effects of Imuthiol were examined in female C3H/HeJ mice 10 weeks after partial neocortical lesions. In animals with right or bilateral neocortical lesions, Imuthiol failed to increase the percentage of spleen T cells, did not influence the expression of class I MHC antigen on these cells, no longer induced the release in serum of specific T-cell-inducing factors, and failed to enhance T-cell-mediated events. In contrast, in animals with a left neocortical lesion, Imuthiol increased T-cell numbers and activities in a fashion that was comparable to that observed in unlesioned controls, but did not enhance NK activity. It is concluded that Imuthiol may affect immune responsiveness by acting directly on the neocortex and/or by interacting at subcortical levels with signals emitted by the neocortex. Moreover, this study reveals a major hemispheric asymmetry in the response to a drug.

Adjuvant treatment of operable stomach cancer with polyadenylic.polyuridylic acid in addition to chemotherapeutic agents. Differential effect on natural killer cell and antibody-dependent cellular cytotoxicity

Peripheral blood lymphocytes of operable stomach cancer patients were evaluated sequentially for their natural killer (NK) and antibody-dependent cellular cytotoxicity (ADCC) activities before and after chemotherapy in association with polyadenylic.polyuridylic acid [poly(A).poly(U)]. Their cytotoxicity was measured by 4 h-chromium release assays, using human K562 and sensitized murine L1210 cells as targets for assays of NK and ADCC respectively. The mean NK cytotoxicity of 89 patients before treatment was significantly lower than that of the 18 sex- and age-matched healthy controls, whereas assays of ADCC showed similar levels of cytotoxicity in both groups. Patients who had received postoperative chemotherapy (5 fluorouracil, 12 mg/kg and adriamycin, 40 mg/M2) once, had, 5 days after injection, NK cytotoxicity levels similar to those before treatment. For these patients, an additional administration of poly(A).poly(U) (100 mg) resulted, 2 days later, in a significant increase in the levels of NK cytotoxicity without affecting the levels of ADCC. Repeated injections of poly(A).poly(U) alternated with chemotherapy induced, consistently, exclusive enhancement of NK activity after each injection. These results suggest that the effector cells for NK and ADCC activities are of functionally different cell populations.

Antibody-dependent natural killer cell-mediated growth inhibition of Cryptococcus neoformans

Previous data from this laboratory indicate that normal murine nylon wool nonadherent splenic cells with characteristics of natural killer (NK) cells effectively inhibit in vitro growth of Cryptococcus neoformans, a yeastlike pathogen. Since NK cells have been shown to be involved in antibody-dependent, cell-mediated cytotoxicity against immunoglobulin G (IgG)-coated tumor cells and xenogenic erythrocytes, we were interested in assessing the effects of the IgG fraction of rabbit anticryptococcal serum on NK cell-mediated inhibition of C. neoformans growth. Early in the study it became apparent that the conventional method of determining the numbers of CFU that was used previously for assessment of viable cryptococci at the end of the growth inhibition assay was not reliable for these studies, owing to minor clumping of the organisms in the presence of anticryptococcal antibody. Therefore, the BACTEC radiometric system was evaluated and determined to be a reliable replacement for the CFU count method. Using the BACTEC methodology, we showed that the anticryptococcal antibody significantly augmented the in vitro ability of NK cells to inhibit the growth of C. neoformans compared with normal rabbit serum or tissue culture medium. Furthermore, the antibody alone did not have an adverse effect on the organism, confirming that reduced growth indices obtained from test wells containing antibody, NK cells, and cryptococci were due to the effects of the NK cells. Maximum anticryptococcal activity of the NK cells was observed in the presence of 16 micrograms of IgG per ml; however, significant augmentation of anticryptococcal activity was seen with antibody concentrations as low as 3 micrograms/ml. Using different populations of murine splenic cells which had varying degrees of NK cell activity, we were able to show that NK cell activities, as determined by 51Cr release from YAC-1 targets, directly correlated with antibody-dependent, cell-mediated growth inhibition against cryptococci, suggesting that NK cells were effector cells in the antibody-dependent assays. Furthermore, in every case, the antibody-dependent activity of NK cells against C. neoformans was higher than the spontaneous activity of NK cells against the organism, emphasizing that NK cell activity against cryptococci can be augmented by specific antibody. When NK cell numbers were enriched by Percoll fractionation of nylon wool nonadherent splenic cells, antibody-dependent and spontaneous growth inhibitory activities of the effector cells were concomitantly augmented, confirming that NK cells were the effector cells in antibody-dependent growth inhibition of cryptococci.(ABSTRACT TRUNCATED AT 400 WORDS)

Eradication of established human melanoma tumors in nude mice by antibody-directed effector cells

The simultaneous injection of monoclonal antibody 9.2.27, directed against a chondroitin sulfate proteoglycan preferentially expressed on human melanoma cells, and 2 X 10(7) mononuclear splenocytes, eradicated established, progressively growing human melanoma tumors in nude mice. Neither splenocytes nor antibody alone achieved significant tumor regression. The cells responsible for tumor elimination are most likely natural killer (NK) cells: they are present in splenocytes of T cell-deficient nude mice, and cloned cells with NK activity are able to suppress tumor growth. Moreover, splenocytes treated with anti-asialo GM1 and complement or harvested from NK-deficient C57BL/6 beige mice did not cause tumor rejection. Furthermore, treatment of BALB/c nude mice just before injection with anti-asialo GM1 antiserum, which is known to eliminate NK activity in vivo, resulted in better tumor growth. In addition, evidence is presented that cells with NK activity are probably the effectors responsible for melanoma target cell lysis in vitro: Antibody-dependent and -independent cell-mediated lysis of M21 melanoma cells was suppressed when splenocytes were preincubated with complement and antibodies specific for cell surface antigens of NK cells, i.e., anti-asialo GM1, anti-Qa5, and anti-NK1.1. Moreover, splenocytes of C57BL/6 beige mice were not able to lyse M21 cells in vitro. These results strongly support the conclusion that cells with NK activity are indeed responsible for the antibody-dependent destruction of M21 melanoma cells in vivo and in vitro.

Participation of natural killer cells in the recovery of mice from visceral leishmaniasis

After infection with the protozoan parasite Leishmania donovani, C57BL/6J bg/bg (beige) mice, which are deficient in natural killer (NK) activity, were unable to control splenic parasite loads relative to phenotypically normal C57BL/6J bg/+ and +/+ mice, particularly beyond 21 days of infection. When beige mice were injected intravenously with 2 or 3 X 10(6) syngeneic, cloned NK cells (NKB61B10 cell line), they displayed splenic parasite burdens which did not differ significantly from those of normal controls. In C57BL/6 +/+ mice rendered NK deficient by split-dose irradiation (four weekly, 200-rad doses of gamma irradiation beginning at 4 weeks of age) splenic and hepatic parasite levels were significantly higher than those in nonirradiated controls at 15 days of infection and beyond. In both sets of experiments, relative degrees of hepato- and splenomegaly were not sufficient to account for differences in parasite burdens among NK-deficient and normal mice. Taken together, the results of these experiments suggest that NK cells may contribute to parasite elimination during the acquired-resistance phase of L. donovani infection in mice.

Natural killer cells--toward clinical application

Natural killer (NK) cells are non-B, non-T lymphoid cells of uncertain lineage that rapidly recognize and lyse a large variety of tumor or virus-infected cells, without the need for either prior sensitization or major histocompatibility complex (MHC)-dependent recognition. Though some essential problems in understanding NK cell function are still unsolved, considerable progress has been achieved in recent years following the identification of the characteristic large granular lymphocyte (LGL) morphology of NK cells and their purification, the study of their function at the single-cell level, and the cloning of mouse and human NK cell lines. Activated mainly by interferon (IFN), as well as important producers of IFN, NK cells appear to have a distinct role in immunoregulation in addition to their postulated major role in "immune surveillance," for which convincing in vivo data has accumulated. Future clinical applications may therefore include manipulations of the NK system through expansion and activation of patient's LGL or the use of cloned human NK cell lines.

Mechanisms of tumour cell escape encountered in treating lymphocytic leukaemia with anti-idiotypic antibody

Four patients with chronic lymphocytic leukaemia were treated by one or more infusions of polyclonal antibody specific for the immunoglobulin idiotype expressed on their leukaemic cells. The antibody was in the form of IgG from sheep antiserum. Three of the 4 cases showed a significant fall in blood lymphocyte count. On one occasion most of the residual circulating lymphocytes were apparently dead. However on all occasions the cell counts rebounded to near pre-infusion levels within one week. Viable lymphocytes recovered from the blood after infusion always showed evidence of antigenic modulation: a diminished level of surface idiotype in a patched distribution, with an accompanying refractoriness to lysis by anti-idiotype plus complement. When cultured in vitro blood lymphocytes from three of the four patients revealed an appreciable export of idiotypic Ig. These 3 patients showed plasma levels of idiotypic Ig up to 400 micrograms ml-1, reduced by plasma exchange prior to infusion. The fourth patient had a level of less than 4 micrograms ml-1, and was the only one in whom free antibody could be found in the plasma after infusion. These cases demonstrate two major factors which thwart antibody attack on leukaemic cells--extracellular antigen and antigenic modulation--as well as problems relating to sparseness of surface antigen, recruitment of effectors, and exhaustion of effectors.

Involvement of brain neocortex and liver in the regulation of T cells: the mode of action of sodium diethyldithiocarbamate (imuthiol)

Sodium diethyldithiocarbamate ( imuthiol ), a non-antigenic and non-carcinogenic compound, devoid of toxic effects at immunostimulant doses, shows distinctive properties in recruitment and activation of T cells. Studies on its mode of action disclosed unsuspected links between the immune system, the endocrine liver and the central nervous system. Evidence was obtained indicating that the brain neocortex modulates T-cell mediated events, most likely via control of specific hormonal synthesis by the liver. The influence of imuthiol is determined at the level of the brain neocortex.

New ultrastructural observations: parallel tubular arrays in human T gamma lymphoid cells

T gamma cells are E-rosetting cells bearing Fc receptors for IgG (E+, Fc gamma + cells). Third population (non-T, non-B) lymphoid cells are also Fc gamma + cells and contain unique inclusions called parallel tubular arrays (PTA). Although T gamma cells and third population lymphoid cells should belong to a similar population of cells, previous ultrastructural studies on purified T gamma cells have failed to reveal the presence of PTA. In this study, we have unequivocally demonstrated PTA in the majority of T gamma cells using simple rosetting techniques. A total of 76 EA hu-rosettes and 108 EA ox-rosettes prepared from an E+ enriched fraction (using sheep erythrocytes as marker particles) were directly examined by electron microscopy. PTA were found in 87% of the EA hu-rosettes and 82% of the EA ox-rosettes. Ammonium chloride, commonly used in other laboratories to lyse erythrocytes during the purification procedure was found to cause a marked decrease in the number of ultrastructurally distinct PTA profiles. In contrast, hypotonic lysis had no effect on cellular ultrastructure. This study showed for the first time that T gamma cells are ultrastructurally similar to other Fc gamma + lymphoid cells and contain PTA as a distinct marker. The significance of our findings to the basic function of this E+ Fc gamma + lymphoid population is discussed.

Natural killer activity in (C57BL/6 X DBA/2)F1 hybrids undergoing acute and chronic graft-vs.-host reaction

The present findings demonstrate that a total i.v. transfer of 100 X 10(6) C57BL/6 (B6) parental spleen cells into untreated (C57BL/6 X DBA/2)F1 hybrids (B6D2F1) resulted in acute runting, which was associated with a significantly elevated graft-vs.-host (GVH) index over a one-month period following GVH induction. Furthermore, this B6-induced acute GVH disease was associated with a marked depression of natural killer (NK) cell activity (spleen and peripheral blood) (with or without addition of mouse fibroblast interferon), which correlated with lymphoid cell hypocellularity, prominent splenic extramedullary hematopoiesis (EMH), and parallel depressions of both concanavalin A- and lipopolysaccharide-induced mitogenesis. Significantly increased killing by antibody-dependent cellular cytotoxicity of antibody-coated chicken red blood cells, as well as increased T cell killing of the NK-insensitive cell line P815 (as compared to the significantly decreased killing of the NK-sensitive cell line YAC-1) was also observed in the spleens of this 100 X 10(6) B6-injected F1 group. In marked contrast to this 100 X 10(6) B6-injected acute GVH group, untreated mice injected i.v. with the same or greater numbers of parental DBA/2 spleen cells (100 X 10(6)-150 X 10(6) DBA/2 spleen cells) exhibited a milder and more chronic form of GVH disease, which was not associated with a significant decrease of NK activity. It was of considerable interest that a total i.v. transfer of 50 X 10(6) B6 spleen cells (i.e. one-half of that required to produce acute GVH, markedly depressed NK, and prominent splenic EMH) into B6D2F1 hybrids also resulted in a more chronic form of GVH disease, but was associated with significantly increased levels of NK activity at two weeks post GVH induction.

Natural killer activity in mice infected with Trypanosoma musculi

Trypanosoma musculi infection affected natural killer (NK) activity in mice. In the spleen, an increase of two to three times normal was displayed on days 2 to 4 after inoculation of parasites, followed by rapid decline to a subnormal level of activity that persisted for more than 3 weeks and included the phase of rapid parasite elimination. NK activity increased dramatically in peritoneal exudate and marrow early in infection, but the subsequent decline was more moderate than in the spleen. The subnormal splenic activity was not elevated by treating infected mice with an interferon inducer, polyinosinic acid-polycytidylic acid. Serum interferon levels were elevated early in infection, but by day 4 postinoculation, they had returned to undetectable. Injection of mice with antiserum to murine interferon-beta did not inhibit the early rise in NK activity or alter the course of trypanosome infection; in fact, the antiserum treatment enhanced splenic NK activity in infected mice. The early rise and subsequent decline of NK activity did not correlate with the course of T. musculi infection and subsequent cure. The cause of the dramatic decline in splenic NK activity is under investigation; it could result, for example, from arousal of suppressor cells, inhibition by prostaglandins, or inhibition by trypanosome-derived substances. Thus, NK cells may be prevented from fulfilling their potential of attacking the extracellular trypanosomes by the effects of inhibitory substances.

Genetic control of murine antibody-dependent cell-mediated cytotoxicity. Partial identity with the genetic control of NK activity

We have observed that the intensity of the direct antibody-dependent cell-mediated cytotoxicity (ADCC) response after an inoculation of foreign tumour cells varies with the strain of mice studied. The inoculation of a human lymphoblastoid cell-line into CBA/J, BALB/c, or DBA/2 mice gives rise to a good cytotoxic response by the host K cells armed with specific antibodies. In contrast, A/J, B10.A, C57BL/6 and B10.S mice respond poorly under the same conditions. The high response is dominant in F1 hybrids between high and low responders and is also expressed among F2 backcrosses with the H-2 phenotype of low responders, suggesting that non-H-2 genes are also implicated in the regulation of ADCC. The genetic control is not exerted at the level of antibody secretion but at that of K-cell activity, since sera from high or low responders are equally effective in arming an ADCC reaction, whereas K cells from low-responder strains are less efficient than those from high-responder strains. The natural killer (NK) activity of the same strains has been screened. The results show a good correlation with some high- and low-responder strains, such as CBA and DBA/2 or A/J and SJL, respectively, but not with C57BL/6, B10.S or B10.A strains. Thus, in addition to common genes controlling both lytic functions, there are specific genetic factors influencing the balance between NK and K cells. These findings confirm the general view that NK and K cells represent only partially identical subsets.

Effects of mitogens on ADCC activity and Fc receptor bearing cells

Murine spleen cells, when activated by various mitogens (Con A, PHA, LPS, BCG) or Con-A conditioned medium show altered behavior as effector cells of antibody-mediated cell cytotoxicity (ADCC) which does not correlate with the expression of Fc-receptors (FcR) at the effector cell surface.

Characterization of effector cells mediating IgG and IgM antibody-dependent cellular cytotoxicity

Spleen effector cells for IgG- and IgM-induced antibody-dependent cellular cytotoxicity (ADCC) were characterized with respect to density and cell surface markers by using sheep erythrocytes (SRBC) coated with hybridoma-derived monoclonal anti-SRBC IgG or anti-SRBC IgM antibodies as targets. While basically the same effector cells are cytolytic for IgG and IgM antibody-coated SRBC, they differ with respect to their relative killing capacity for IgG- versus IgM-coated target cells. On the basis of physical and biochemical properties three populations with cytolytic capacity could be separated: (I) A light fraction of large cells had high cytolytic potential for both IgG- and IgM-coated SRBC. The cells were negative for the Fc receptor for IgG (Fc gamma-R-) and the C3-receptor (C3-R-), they carried the receptor for Helix pomatia A agglutinin (HP-A+), and reactivity was strongly reduced after treatment with anti-Thy-1 and complement (C). (II) High activity was also observed with a medium-dense fraction, preferably lysing IgG antibody-coated cells. The cells were Fc gamma-R+, partly C3-R+, mostly HP-A-, and only a minor portion of the cells were Thy-1+. (III) A dense fraction, displaying on a per cell basis low cytolytic potential, was more active in IgM than IgG ADCC. The cells were Fc gamma-R+, HP-A+ and Thy-1+. All three effector cell populations were non-adherent, non-phagocytic, and surface immunoglobulin-negative (s-Ig-).

The decline of immunological resistance of aging mice to Trypanosoma musculi

Aged mice of several strains studied developed much more severe infections of Trypanosoma musculi (mouse-specific parasite) than did young adults. Reduced resistance of the aged mice, assessed from the resistance conferred on irradiated recipients by transfer of normal and infected donor spleen cells, resulted from a much slower development of immunity to the parasite, reflecting depleted immune competence, and from the expression in aged mice of an altered internal milieu unfavorable for normal function of lymphoid cells. An analysis of antibody-dependent cytotoxic reactions against T. musculi revealed no differences; therefore, intrinsic changes in antibody-dependent cytotoxic effector cells are not responsible for the decline in resistance to trypanosomes. The possibility that quantitative or qualitative changes in humoral antibody production might account for defective resistance of aged mice was minimized by demonstrating that antibodies play a minor role in the recovery from infection with T. musculi. Evidence of a significant role (possibly indirect) of macrophages in resistance to T. musculi was obtained. Altogether, our data raise the possibility that the decline in natural killer activity that is susceptible to amplification by macrophage-derived interferon may account for the defective resistance of aged mice to trypanosomes.

Comparative analysis of cell surface markers on murine NK cells and CTL target-effector conjugates

The rosetting of sheep erythrocytes (SRBC) coated with non-haemagglutinating monoclonal antibodies rather than conventional haemagglutinating antisera revealed readily detectable FcR on most splenic natural killer (NK) cells since 76% of splenic lymphocytes forming conjugates with YAC also rosetted with SRBC coated with high concentrations of monoclonal anti-SRBC antibody of the IgG2b subclass and since Ficoll depletion or enrichment of splenic lymphocytes rosetting with IgG2b-coated SRBC resulted in a corresponding 4-fold decrease or increase in conjugate-forming cells and a 10-fold decrease or increase in NK cytolytic activity. NK cells bound much less readily to monoclonal IgG2a and not at all to monoclonal IgG1 or IgM, but the degree of binding was directly proportional to the amount of antibody on the erythrocytes and was not isotope-restricted. In addition, immunofluorescent studies revealed that YAC-1-conjugated lymphocytes were Lyt-1-, Lyt-2-, partially Thy-1+ (60%), asialo(GM1+ (80%). Qa-4+ (77%), Qa-5+ (79%), and Ly-5+ (94%). In comparison, a proportion (39%) of alloimmune peritoneal exudate cells which conjugated with P815-2 also stained by immunofluorescence with anti-asialo GM1 antisera. Most (greater than 90%) P815-conjugated cells were Thy-1+, Lyt-2%, and a subpopulation of Lyt-1+2+ conjugates was observed (25%). Qa-5 and Ly-5 were also expressed on most (two-thirds) cytolytic T lymphocytes (CTL) conjugates, whereas Qa-4 and FcR for IgG2b were not detected. The best phenotype distinctions between NK cells and CTL were therefore based on the presence or absence of Lyt-2, Qa-4, and FcR for IgG2b on most effector cells. Anti-asialo-GM1 or monoclonal anti-Qa-4 and complement treatment greatly diminished both the frequency of NK conjugates and the percentage of conjugates with detectable IgG2b FcR or asialo-GM1. These results confirm that NK cells co-express asialo-GM1 and Fc receptors, at the single-cell level, and provide a simple method for greatly enriching NK populations at least 10-fold.

Natural killer cell activity and antibody-dependent cellular cytotoxicity in newborn infants

The ability of lymphocytes from the peripheral blood of preterm and term infants and adult women and men to mediate natural killing (NK) and K cell activity (antibody-dependent cellular cytotoxicity) was analysed in 4 hours 51Cr-release assays. K 562 cells were targets for NK activity. K cell activity was assayed on antibody-coated rat thymocytes. Lymphocytes from adult male donors were significantly more cytotoxic to K 562 cells than were lymphocytes from adult female donors. Lymphocytes from both preterm and term infants had significantly lower NK and K cell activity than lymphocytes from adult donors. During the first month of life no increase in NK activity or K cell activity occurred in 7 infants who were re-examined. It is concluded that neither NK nor K cell activities are fully developed during the first month of life.

Natural killer cells do not belong to the recirculating lymphocyte population

Natural Killer (NK) cells constitute a cell type with an as yet undefined lineage, although certain similarities with T lymphocytes have been found in the mouse. Our present results show that NK cells have a significant difference compared with T and B cells in their capacity to traverse the blood-lymph barrier. Thoracic duct lymphocytes from mice or rats are thus devoid of NK activity, when at the same time potential, cytotoxic T lymphocyte (CTL) activity or antibody-dependent cellular cytotoxicity function can be demonstrated. Chronic thoracic duct drainage in the rat also leads to an increase in NK activity per unit cell number in the other lymphoid organs. Thoracic duct lymphocytes from mice and rats may thus serve as convenient sources of CTL and/or killer cells in situations in which it is important to minimize NK cell involvement.

Antibody-dependent cell-mediated cytotoxicity in human cancer: characterization of patient leukocyte activity and treatment effects

Antibody-dependent cell-mediated cytotoxicity (ADCC), medicated by peripheral blood Hypaque-Ficoll separated mononuclear cells, was studied in humans using chicken erythrocytes (CRBC) incubated in a 1:1200 dilution of rabbit anti-CRBC and human B erythrocytes (HRBC) incubation in a 1:20 dilution of isoantibody. At the optimal target effector ratio of 3:1, ADCC to both CRBC and HRBC was significantly higher than normal in 27 lung cancer, 18 malignant melanoma, and seven colon cancer patients, but not in 20 breast cancer patients. Chemotherapy (single-agent or combination) in 12 patients did not effect ADCC in vitro but significantly suppressed ADCC to both targets after only four or five days of therapy in vivo (ADCC to CRBC, 47.4 to 24.1% lysis: ADCC to HRBC, 48.1 to 16.3% lysis). Immunotherapy with intravenous (IV) corynebacterium parvum or IV methanol extraction residue of BCG (MER) boosted ADCC to both targets within four to seven days of the first dose. It was found that ADCC to HRBC but not to CRBC was completely absent in three cases of active hairy cell leukemia but was present in two cases in remission. The ADCC to HRBC showed an age-dependent increase in both the 51 normal subject and the cancer patients. This was not observed for ADCC to CRBC. The ADCC to CRBC was mediated mainly by an Fc-receptor-positive, nonadherent, small lymphocyte, and ADCC to HRBC was mediated entirely by an adherent monocyte. The ADCC did not correlate significantly with the H3 thymidine incorporation of peripheral blood mononuclear cells, cultured without stimulation for either one or seven days. It also did not correlate with the number of residual granulocytes in the mononuclear cell suspensions. Measurement of ADCC is a useful method of characterizing host defense in malignant disease and its modification by therapy.

Modulation of antibody-dependent cellular cytotoxicity against chicken erythrocyte targets by adriamycin and daunorubicin

Peritoneal exudate cells isolated from Adriamycin (AM) or daunorubicin (DM)-treated mice demonstrated an increased ability to mediate antibody-dependent cellular cytotoxicity (ADCC) against antibody-coated chicken red blood cell targets. Following initial suppression of this cell-mediated function 3 days after a single injection, increased effector cell efficiency occurred to an equal degree in both groups of drug treated mice by day 10 compared to controls. This increase in ADCC activity occurred in parallel with a decrease in the total number of peritoneal cells recovered. It is hypothesized that the drugs acted to modulate ADCC in two ways: 1) suppression by induction of suppressor cell activity, and 2) enhancement by elimination of suppressor cells which resulted in increased effector activity of the remaining cells.