Natural killer cell function and interferon generation in patients with primary immunodeficiencies

IB-367 pre-treatment improves the in vivo efficacy of teicoplanin and daptomycin in an animal model of wounds infected with meticillin-resistant Staphylococcus aureus

Antimicrobial peptides are known as immunomodulators and antibiotic enhancers. We report that administration of an antimicrobial peptide, IB-367, was efficacious in increasing the antimicrobial activity of daptomycin and teicoplanin in a mouse model of wound infection caused by meticillin-resistant Staphylococcus aureus (MRSA). Mice were assigned to seven groups: an IB-367 pre-treated group with no antibiotics given after challenge, two IB-367 pre-treated groups plus daptomycin or teicoplanin given after challenge, two groups treated with daptomycin or teicoplanin only after challenge, and two control groups without infection or that did not receive any treatment. The main outcome measures were quantitative bacterial culture and analysis of natural killer (NK) cytotoxicity and leukocyte phenotype. The wound, established through the panniculus carnosus muscle of mice, was infected by MRSA. Bacterial cultures of mice receiving antibiotics alone showed a −2 log decrease, whilst those for IB-367 plus daptomycin or teicoplanin showed a −4 log decrease. IB-367 plus daptomycin showed the highest efficacy. The higher antimicrobial effect exerted by IB-367 was associated with increased levels of NK cytotoxicity but not of NK cell number. IB-367 increased the number of both CD11b and Gr-1 cells 3 days after MRSA challenge, whereas both of these leukocyte populations were reduced at 10 days after challenge. Our data suggest that a combination of IB-367 with antibiotic exerts a therapeutic effect and may be useful for the management of staphylococcal wounds.

WIP remodeling actin behind the scenes: how WIP reshapes immune and other functions

Actin polymerization is a fundamental cellular process regulating immune cell functions and the immune response. The Wiskott-Aldrich syndrome protein (WASp) is an actin nucleation promoting factor, which is exclusively expressed in hematopoietic cells, where it plays a key regulatory role in cytoskeletal dynamics. WASp interacting protein (WIP) was first discovered as the binding partner of WASp, through the use of the yeast two hybrid system. WIP was later identified as a chaperone of WASp, necessary for its stability. Mutations occurring at the WASp homology 1 domain (WH1), which serves as the WIP binding site, were found to cause the Wiskott-Aldrich syndrome (WAS) and X-linked thrombocytopenia (XLT). WAS manifests as an immune deficiency characterized by eczema, thrombocytopenia, recurrent infections, and hematopoietic malignancies, demonstrating the importance of WIP for WASp complex formation and for a proper immune response. WIP deficiency was found to lead to different abnormalities in the activity of various lymphocytes, suggesting differential cell-dependent roles for WIP. Additionally, WIP deficiency causes cellular abnormalities not found in WASp-deficient cells, indicating that WIP fulfills roles beyond stabilizing WASp. Indeed, WIP was shown to interact with various binding partners, including the signaling proteins Nck, CrkL and cortactin. Recent studies have demonstrated that WIP also takes part in non immune cellular processes such as cancer invasion and metastasis, in addition to cell subversion by intracellular pathogens. Understanding of numerous functions of WIP can enhance our current understanding of activation and function of immune and other cell types.

Wiskott-Aldrich Syndrome: Immunodeficiency resulting from defective cell migration and impaired immunostimulatory activation

Regulation of the actin cytoskeleton is crucial for many aspects of correct and cooperative functioning of immune cells, such as migration, antigen uptake and cell activation. The Wiskott-Aldrich Syndrome protein (WASp) is an important regulator of actin cytoskeletal rearrangements and lack of this protein results in impaired immune function. This review discusses recent new insights of the role of WASp at molecular and cellular level and evaluates how WASp deficiency affects important immunological features and how defective immune cell function contributes to compromised host defence.

Macrophages and cytokines in the early defence against herpes simplex virus

Herpes simplex virus (HSV) type 1 and 2 are old viruses, with a history of evolution shared with humans. Thus, it is generally well-adapted viruses, infecting many of us without doing much harm, and with the capacity to hide in our neurons for life. In rare situations, however, the primary infection becomes generalized or involves the brain. Normally, the primary HSV infection is asymptomatic, and a crucial element in the early restriction of virus replication and thus avoidance of symptoms from the infection is the concerted action of different arms of the innate immune response. An early and light struggle inhibiting some HSV replication will spare the host from the real war against huge amounts of virus later in infection. As far as such a war will jeopardize the life of the host, it will be in both interests, including the virus, to settle the conflict amicably. Some important weapons of the unspecific defence and the early strikes and beginning battle during the first days of a HSV infection are discussed in this review. Generally, macrophages are orchestrating a multitude of anti-herpetic actions during the first hours of the attack. In a first wave of responses, cytokines, primarily type I interferons (IFN) and tumour necrosis factor are produced and exert a direct antiviral effect and activate the macrophages themselves. In the next wave, interleukin (IL)-12 together with the above and other cytokines induce production of IFN-gamma in mainly NK cells. Many positive feed-back mechanisms and synergistic interactions intensify these systems and give rise to heavy antiviral weapons such as reactive oxygen species and nitric oxide. This results in the generation of an alliance against the viral enemy. However, these heavy weapons have to be controlled to avoid too much harm to the host. By IL-4 and others, these reactions are hampered, but they are still allowed in foci of HSV replication, thus focusing the activity to only relevant sites. So, no hero does it alone. Rather, an alliance of cytokines, macrophages and other cells seems to play a central role. Implications of this for future treatment modalities are shortly considered.

Human natural killer cell deficiencies and susceptibility to infection

There are a surprisingly large number of human natural killer (NK) cell deficiency states that provide insight into the role of NK cells in defense against human infectious disease. Many disorders associated with NK cell defects are caused by single gene mutations and, thus, give additional understanding concerning the function of specific molecules in NK cell development and activities. A resounding theme of NK cell deficiencies is susceptibility to herpesviruses, suggesting that unexplained severe herpesviral infection should raise the possibility of an NK cell deficit.

Wiskott-Aldrich syndrome protein is required for NK cell cytotoxicity and colocalizes with actin to NK cell-activating immunologic synapses

The Wiskott-Aldrich syndrome (WAS) is a primary immunodeficiency disorder caused by a mutation in WAS protein (WASp) that results in defective actin polymerization. Although the function of many hematopoietic cells requires WASp, the specific expression and function of this molecule in natural killer (NK) cells is unknown. Here, we report that WAS patients have increased percentages of peripheral blood NK cells and that fresh enriched NK cells from two patients with a WASp mutation have defective cytolytic function. In normal NK cells, WASp was expressed and localized to the activating immunologic synapse (IS) with filamentous actin (F-actin). Perforin also localized to the NK cell-activating IS but at a lesser frequency than F-actin and WASp. The accumulation of F-actin and WASp at the activating IS was decreased significantly in NK cells that had been treated with the inhibitor of actin polymerization, cytochalasin D. NK cells from WAS patients lacked expression of WASp and accumulated F-actin at the activating IS infrequently. Thus, WASp has an important function in NK cells. In patients with WASp mutations, the resulting NK cell defects are likely to contribute to their disease.

Chemotherapeutic purine analogs alter the level of interferon-beta mRNA induced by poly I-poly C in cultured osteosarcoma cells

The purine nucleoside analogs fludarabine, 2-chlorodeoxyadenosine, and 2'-deoxycoformycin exhibit impressive activity in lymphoproliferative malignancies of adults and children. Their mechanism of action is not clear. Studies have suggested that their use is associated with significant myelosuppression, immunosuppression, and in some circumstances, increased infection with viral and opportunistic pathogens. Because interferons (IFNs) are known to have immunomodulatory activity as well as potent antiproliferative and antiviral activity, we examined whether the chemotherapeutic purine nucleoside analogs alter interferon-beta (IFN-B) gene expression in MG63 in human osteosarcoma cells. Northern blot analysis showed a dose-dependent inhibition of IFN-B mRNA accumulation in response to a known inducer (Poly I-Poly C) all three purine analogs. Hybridization analysis also revealed that inhibition of IFN-beta mRNA accumulation by the purine analogs is not a result of decreased mRNA stability. Further analysis of gene expression by PCR differential display indicated that the effect of the purine analogs was restricted to only a limited number of inducible genes. The data suggest that these molecules alter the signaling process involved in regulating the expression of specific genes, including IFN-beta. These findings predict that the use of purine nucleoside analogs may reduce IFN production in vivo and thereby abrogate host defenses against infectious pathogens.

Thymosin alpha 1 effects, in vitro, on lymphokine-activated killer cells from patients with primary immunodeficiencies: preliminary results

In patients with primary immunodeficiencies the role of natural killer (NK)- and lymphokine (IL-2)-activated killer (LAK)-cells is not yet satisfactorily established. Using a clonogenic assay with K562 leukemia target cells, we studied their NK- and LAK-cell activity in vitro. Moreover, the effect of thymosin alpha 1 (T alpha 1) on LAK-cell activity was studied in 11 patients with different immunodeficiencies. The results were compared with data of healthy controls (n = 11) and cord blood samples (n = 6). Common variable immunodeficiency patients demonstrated a mean LAK-cell activity of about 65% of normal controls and cord blood samples. The moderately reduced LAK-cell activity was not affected by T alpha 1. In the immunodeficient other patients, low levels of LAK-cell activity with a mean value of 10% of normal controls were seen. The mean LAK-cell activity could be improved by T alpha 1: three patients showed an improvement of their LAK-cell activity up to 25-30% after T alpha 1 administration in vitro, but in one case T alpha 1 was without any effect. Analysis of the expression of the surface markers CD8, CD16, CD57 and CD8/CD57 revealed that only CD16 positive lymphocytes were significantly less in immunodeficient patients. We found a linear correlation between LAK-cell activity and CD8/CD57 double positive lymphocytes in all patients. Our results demonstrate that suppressed LAK-cell activity from immunodeficient patients can be individually improved by T alpha 1. Further in vivo studies should evaluate thymic peptide immunotherapy for individual immunodeficient patients.

Interferon-alpha generation in mice responding to challenge with UV-inactivated herpes simplex virus

In humans with advanced human immunodeficiency virus (HIV) infection, an interferon-alpha (IFN-alpha) response by a specialized blood mononuclear cell to herpes simplex virus (HSV) in vitro is associated with resistance to opportunistic infections. A cell type of unknown lineage, designated the natural IFN-producing cell (NIPC), has been identified preliminarily as the source of these IFNs and may have a role in other host defense functions. Earlier studies suggested the existence of analogous HSV-responsive cell populations in mice. The role specifically of IFN-alpha in the murine system, however, has not been characterized. Using IFN bioassay and neutralization with antisera against Type I IFNs and IFN-beta, we have defined the types and sources of IFNs produced by mice in response to in vivo and in vitro challenge with UV-inactivated HSV. After intraperitoneal inoculation with HSV, BALB/c and C57Bl/6 strains produced characteristically different levels of serum IFNs that appeared principally to be IFN-alpha. The response of mononuclear cells from these mice differed from that of the intact mouse. Isolated cells from bone marrow and spleen released detectable IFNs much later than did whole animals, and the IFNs produced by marrow, spleen, and peritoneal cells were usually neutralized by the anti-IFN-beta. Only bone marrow cells produced detectable amounts of IFN-alpha. Both intact mice and their cells became refractory to restimulation with similar kinetics.

The first Icelandic family with X-linked agammaglobulinaemia: studies of genetic markers and immune function

This paper describes studies of genetic markers and immune functions in the first Icelandic family identified with X-linked agammaglobulinaemia (X-LA), including three affected brothers. The eldest brother was diagnosed at the age of 9 in 1963. He suffered repeated infections and died at the age of 23. The other two affected brothers, diagnosed at 6 years and 1 year of age, are alive and well on immunoglobulin replacement therapy at the ages of 32 and 24. All were typed for HLA, complement, and various other markers. Pedigree analysis suggests an X-linked segregation of the disease. Their serum IgG is maintained at normal levels on therapy. Several parameters of immune function were studied. The following results were obtained for the X-LA brothers: B cells are absent in their peripheral blood samples. T-cell numbers are normal, but monocytes are increased in numbers and activity. No immunoglobulin production could be elicited in vitro with PWM and no cells containing cytoplasmic Ig were detectable among PWM-stimulated blasts. Nevertheless the proliferative response was particularly vigorous, but the responding cells were shown to be exclusively T cells. No blast transformation could be achieved with EB virus. NK-cell activity was normal/high normal. Other cell-mediated immune functions were normal. In conclusion our data indicate that the differentiation of B cells is blocked in the two surviving X-LA brothers. They have survived for a longer time and in better health than is generally reported. Early diagnosis and adequate replacement treatment with Ig is clearly crucial. Vigorous non-specific immune mechanisms may help to compensate for the defective specific immunity.

Lymphokine-activated killer cells in primary immunodeficiencies and acquired immunodeficiency syndrome

Cytotoxic mechanisms (e.g., natural killer (NK) lysis, antibody-dependent cellular cytotoxicity, and cytotoxic T lymphocyte lysis) play an important role in host defense against various infections and neoplasms. Lymphokine-activated killer (LAK) cytotoxicity, induced in vitro by incubating mononuclear cells with interleukin 2 (IL-2) for 2-5 days, may also represent an important component of the body's cytotoxic repertoire. In 10 patients with congenital cellular immunodeficiencies, including 5 with severe combined immunodeficiency, the mean LAK activity in a 3-hr chromium release assay against Raji target cells was 44 +/- 8.1%, which is equivalent to that observed in normal adults and neonates. In only one case, a patient with reticular dysgenesis, was there absent LAK cell generation. Haploidentical T cell-depleted bone marrow transplantation (BMT) restored LAK activity in this patient. LAK activity was first observed in this patient and two others 3-6 weeks following BMT, prior to other evidence of immunologic engraftment such as lymphocyte proliferation to mitogens, NK activity, or interferon-gamma production. One patient with adenosine deaminase deficiency showed normal levels of LAK activity despite absent NK activity. Three patients with chronic granulomatous disease also had normal LAK activity (57 +/- 14% specific lysis). In 9 patients with acquired immunodeficiency syndrome (AIDS), IL-2 activation resulted in a mean cytotoxic activity of 56 +/- 8.7% toward Raji targets. In addition, 9 patients with pre-AIDS complex also showed normal levels of cytotoxicity (37 +/- 3.3% toward Raji targets), equivalent to that of 8 normal controls, including two healthy homosexual males (mean lysis 38 +/- 3.9%). These results indicate that LAK cells appear early in immunologic ontogeny. Further, the mechanism of lysis is not oxygen dependent since LAK activity was present in the 3 patients with chronic granulomatous disease. The ability to generate LAK in a wide spectrum of immunodeficiencies may indicate that IL-2 could be used in therapy of such disorders.

Abrogated NK-cell lysis of human papillomavirus (HPV)-16-bearing keratinocytes in patients with pre-cancerous and cancerous HPV-induced anogenital lesions

Natural-cell-mediated cytotoxicity against K-562 erythroleukemic cells and human papillomavirus (HPV)-16 harboring Sk-v keratinocytes was tested in 38 age- and sex-matched healthy volunteers and in patients with HPV-induced benign and malignant anogenital lesions: 9 persons with HPV-16-induced bowenoid papulosis (BP), 8 with anogenital carcinomas (5 with HPV-16- or 33-associated squamous-cell carcinomas of Bowen's type and 3 with HPV-6-associated Buschke-Loewenstein verrucous carcinomas) and 12 with HPV-6-induced condylomata acuminata. Both K-562 and Sk-v cells were killed by a non-adherent CD16+ subset of PBMC as revealed by cell fractionation on the basis of their adherence to plastic and by treatment with Leu-IIb monoclonal antibody (MAb) and complement. "Cold" target competitive assays demonstrated that both cell types inhibited lysis of labelled Sk-v cells. In patients with BP and anogenital carcinomas induced by HPV-16 or 33, there was a significant (at least at p less than 0.01) decrease of Sk-v cell lysis as compared with the healthy control group. Anti-K-562 activity was not affected. In patients with anogenital carcinomas the degree of Sk-v lysis was decreased in proportion to the duration of lesions (correlation coefficient-r = -0.79). Neither anti-K-562 nor anti-Sk-v cytotoxicities were significantly affected in patients with condylomata and with HPV-6 associated verrucous carcinomas. Short-term (3 hr) pre-incubation of normal PBMC with sera from patients with BP and HPV-16-associated anogenital carcinomas resulted in significant inhibition of their ability to lyse Sk-v cells. Lysis of K-562 cells remained unaffected. In patients with carcinomas, the suppressive effect of sera was associated with a lowering of the ability of their PBMC to lyse Sk-v cells (r = -0.79). In patients with longer tumor persistence, the suppressive effect of serum was proportionally higher (r = 0.86).

Phenotypical and functional heterogeneity of the large granular lymphocytes increased after various treatments in a patient with combined immunodeficiency

A boy with combined immunodeficiency having low natural killer (NK)-cell activity received thymopoietin pentapeptide (TP-5) treatment, transplanted with T cell-depleted HLA-haploidentical bone marrow (BMT) cells from his father and with thymus tissue from an infant at different times during the first year of life. He showed a marked increase in large granular lymphocytes (LGL) both during the treatment with TP-5 and after BMT. The LGL generated following TP-5 injection had a T3+Leu11- surface phenotype and low NK activity. In contrast, the LGL appearing after BMT showed T3-, Leu7+, and/or Leu11+ surface phenotypes, had high NK- and K-cell activities, and were lymphokine-activated killer (LAK)-cell precursors. These killer activities were assigned to the Leu7-Leu11+ subset and proved to be of recipient origin. LGL proliferation following BMT was accompanied by neutropenia, which was improved in association with a reduction in the number of LGL and the appearance of T cells of BMT donor origin following thymus transplantation. This suggested the inhibition of granulopoiesis by the LGL and an in vitro study revealed that the Leu7+Leu11- subset of LGL suppressed the growth of granulocyte/macrophage colony-forming units. These results indicated that phenotypically different LGL could be generated by different treatments and that the LGL showing NK activity were distinct from those regulating granulopoiesis. It was also suggested that the generation of LGL was controlled by T cells.

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.

Natural killer (NK)-cell activity in sorted subsets of peripheral blood mononuclear cells from patients with severe combined immunodeficiency

Natural killer-cell activity for K562 target cells was measured in 13 patients with severe combined immunodeficiency before bone marrow transplantation. Both unseparated peripheral blood mononuclear cells and sorted cell subsets (B73.1 positive, B73.1 negative, OKT3 positive, OKT3 negative) were tested. Heterogeneity of natural killer-cell activity was observed, the level of which did not correlate with the usual subdivision of severe combined immunodeficiency, as defined by a scientific group on immunodeficiency for the WHO. In those patients in whom natural killer-cell activity was observed in unseparated cells, testing of this function in sorted cell subsets revealed some unexpected findings. In three of four patients, B73.1-negative cells showed remarkable natural killer-cell activity. In addition, in one of these patients, no activity was observed in the B73.1-positive cells.