穿孔素与颗粒酶B在鼻NK/T细胞淋巴瘤诊断中的意义

目的　检测鼻NK/T细胞淋巴瘤中的穿孔素、颗粒酶B表达分布情况 ,为临床治疗和预后判断提供依据。方法　运用免疫组化S P法检测 11例鼻NK/T细胞淋巴瘤中穿孔素、颗粒酶B的表达和分布情况 ;同时与组织芯片中其他类型淋巴瘤进行比较研究 ,10例淋巴组织反应性增生作为对照。结果　 11例鼻NK/T细胞淋巴瘤中均见穿孔素和颗粒酶B过度表达。以 6 0例淋巴瘤制成组织芯片的 4 2例B细胞淋巴瘤中见 11例少许穿孔素和 14例少许颗粒酶B阳性表达细胞散在分布于瘤细胞间 ,10例外周T细胞淋巴瘤中 8例少许表达穿孔素和 9例少许表达颗粒酶B。 2例间变性大细胞淋巴瘤见少许穿孔素和颗粒酶B阳性表达细胞。 2例霍奇金淋巴瘤阴性。NK/T细胞淋巴瘤的穿孔素和颗粒酶B表达程度与T、B淋巴瘤比较 ,差异有显著性 (P <0 0 1)。结论　穿孔素和颗粒酶B是鉴定活化的细胞毒性细胞的免疫标记物 ,可作为NK/T细胞淋巴瘤的诊断性标记物 ;其在外周T细胞淋巴瘤和B细胞淋巴瘤中的表达 ,反映了机体存在抗肿瘤的免疫反应机制。     

Levels of granzyme B, perforin and Fas ligand antigens and mRNAs in patients following allogeneic hematopoietic stem cell transplantation

In order to monitor the immunological status of patients after allogeneic hematopoietic stem cell transplantation(HSCT), granzyme B(GrB), perforin(PRF) and Fas ligand(L) antigens and mRNAs were measured by flow cytometry and real time RT-PCR, respectively. Cytoplasmic antigens were detected in whole blood after fixation and pretreatment with saponin. Real time PCR was carried out using extracted RNA from buffy coat. We measured these substances in a cytotoxic T cell clone, a natural killer cell line, and peripheral blood collected from 11 patients after HSCT. Although changes in antigen levels were not detected, increased levels of GrB and Fas L mRNAs were quantitatively measured in CTLs and NK cells stimulated by IL-2 combined with IL-12. Increased levels of GrB and/or PRF antigens were detected in four of five patients with chronic GVHD. Increased mRNA levels were also observed in one or more of GrB, PRF or Fas L in four of five patients with cGVHD, although there was a discrepancy between antigen and mRNA positivity. Four of six patients without cGVHD were positive for apoptosis-inducing factors, either by antigen detection or RT-PCR. One of these four had relapsing leukemia, and another had herpes zoster infection, while the reasons for positive results in the other two patients are not clear. Although changes in antigen levels did not parallel those in mRNA, measurement of these parameters may assist in predicting GVHD, GVL and infections following HSCT.     

NK cells recover early and mediate cytotoxicity via perforin/granzyme and Fas/FasL pathways in umbilical cord blood recipients

Umbilical cord blood (UCB) is now widely accepted as a source of stem cells in patients with malignant hematologic and genetic disorders. We have recently reported that in a series of 30 pediatric UCB transplant recipients comparable outcome to that anticipated with other unrelated stem cell sources. In our series, however, the probability of GVHD for grade III-IV was 9% and no UCB recipient developed chronic GVHD. The reason for the low incidence of GVHD after UCB transplantation is not fully understood. Because functional NK cells are among the first population of lymphocytes to be detected in UCB transplant recipients, 2 months post-transplant on average, we wanted to establish whether NK cells could be implicated in reducing the risk of GVHD. Here, we confirm that early NK cells detected in UCB transplant recipients activate the granzyme/perforin lytic pathway and, in addition, they can mediate Fas/Fas ligand (FasL) activity, a finding not previously reported. Both pathways develop simultaneously and are detectable months before the other lymphocytes, notably CD8 are fully functional. Our contention, therefore, is that the low GVHD observed in UCB recipients may be partially due to early NK cells.     

外周血淋巴细胞穿孔素和颗粒酶B mRNA检测对肾移植急性排斥反应的早期诊断价值

探讨外周血淋巴细胞(peripheral blood lymphocyte,PBL)穿孔素和颗粒酶B mRNA检测对肾移植急性排斥反应(AR)的早期诊断价值。采用RT-PCR方法动态检测67例肾移植AR患者外周血淋巴细胞穿孔素和颗粒酶B mRNA的表达水平,同时检测所有患者肌酐(Cr)表达水平情况,比较各时间点穿孔素、颗粒酶B mRNA及Cr表达水平,并探讨穿孔素、颗粒酶B与AR的关系。移植后1d与移植前1d比较,PBL穿孔素、颗粒酶B mRNA表达水平比较无明显差异性(P>0.05),Cr表达水平明显下降(P<0.05);AR前3d较之前各时间点比较,PBL穿孔素、颗粒酶B mRNA表达水平明显上升(P<0.05),而Cr表达水平明显下降(P<0.05);AR后1d时PBL穿孔素、颗粒酶B mRNA表达水平达到最高峰,随后逐渐下降(P<0.05),而AR后5d时Cr表达水平达到最高峰,随后逐渐下降(P<0.05);PBL穿孔素、颗粒酶B mRNA表达水平升高时间比Cr早4d,AR患者经MP/OKT3冲击治疗后,PBL穿孔素和颗粒酶B mRNA表达水平逐渐降低至原有基础水平。PBL穿孔素和颗粒酶B mRNA在AR早期诊断和抗排斥反应疗效评估等方面具有一定的临床价值。     

人外周血NK细胞在细胞因子刺激下扩增后穿孔素、颗粒酶B基因表达的变化

目的 探讨经过纯化及在多种细胞因子的作用下扩增后的NK细胞,其穿孔素(per-furin)、颗粒酶B(granzyme B)表达水平的改变与细胞杀伤率的关系.方法 应用竞争性定量RT-PCR方法 检测了8例供者纯化、扩增后NK细胞的穿孔素、颗粒酶B基因表达水平,同时检测其对K562细胞的杀伤率.结果 经纯化、扩增后的NK细胞,在多种细胞因子作用下穿孔素和颗粒酶B的基因表达水平明显提高,且.IL-2+IL-15组、IL-2+IL-12+IL-15组基因的表达量均显著高于其他组,NK细胞对K562的杀伤率结果 与基因表达水平一致.结论 应用细胞因子后可使NK细胞的穿孔素、颗粒酶B基因表达水平明显提高,同时提高了NK细胞的杀伤功能.     

Co-expression of perforin and granzyme B genes induces apoptosis and inhibits the tumorigenicity of laryngeal cancer cell line Hep-2

Granzyme B and perforin, two of the most important components, have shown anticancer properties in various cancers, but their effects in laryngeal cancer remain unexplored. Here we decided to examine the effects of Granzyme B and perforin in Hep-2 cells and clarify the role of perforin and granzyme B in the tumorigenicity of laryngeal cancer cell line. Hep-2 cells were transfected with pVAX1-PIG co-expression vector (comprising perforin and granzyme B genes), and then the growth and apoptosis of these Hep-2 cells were evaluated. The tumorigenicity of Hep-2 cell line co-expressing perforin and granzyme B genes was tested in BALB/c nu/nu mice. We found that the co-expression of perforin and granzyme B genes could obviously inhibit cell focus formation and induce cell apoptosis in Hep-2 cells. Furthermore, after subcutaneous injection of Hep-2 cells transfected with pVAX1-PIG, an extensive delay in tumor growth was observed in BALB/c-nu/nu mice. Moreover, our studies demonstrated that the anticancer activity of perforin and granzyme B was sustainable in vivo as tumor development by inducing cell apoptosis. Taken together, our data indicate that the co-expression of perforin and granzyme B genes exhibits anticancer potential, and hopefully provide potential therapeutic applications in laryngeal cancer.     

Prednisolone suppresses NK cell cytotoxicity in vitro in women with a history of infertility and elevated NK cell cytotoxicity

PROBLEM: To evaluate the effect of prednisolone on NK cell cytotoxicity in vitro environment and also to compare the effect of prednisolone versus immunoglobulin-G (IVIG) on NK cell cytotoxicity using in vitro co-culture with K562 cells. METHOD OF STUDY: The following is a prospective observational study, between August 2006 and February 2007, was carried out on blood samples from 110 patients with a history of recurrent miscarriage or recurrent failed implantation. Peripheral blood mononuclear cells containing NK cells were isolated and co-cultured with target cell K562 in three different effector-to-target (E:T) ratios of 50:1, 25:1 and 12.5:1. Prednisolone or IVIG was then added to the tube with E:T ratio of 50:1 to assess suppressive effect. The percentage killing was recorded and statistical analysis performed using Student's t-test. RESULTS: In the experiments with an E:T ratio of 50:1 without prednisolone or IVIG in the co-culture, the mean target cell killing percentage was 26.4%. In cultures using the same E:T ratio, this killing percentage was significantly reduced in the presence of IVIG (9.9%) or prednisolone (13.6%), (P<0.001 in both analyses). On comparing the reduction in killing percentage of target cells by prednisolone versus IVIG, a slightly lower reduction in the prednisolone co-culture was noted but this was not statistically significant (P>0.05). CONCLUSION: The results of this study show that prednisolone is able to suppress the cytolytic activity of the NK cell. Prednisolone and IVIG are almost equally effective in suppressing in vitro NK cell cytolytic activity.     

Differential expression of perforin and granzyme B in the liver of patients with chronic hepatitis C

T lymphocytes have been reported to be the predominant inflammatory cells in the liver of patients with chronic hepatitis C. On activation, CD8+ T lymphocytes can exert their cytolytic activity by releasing their granule components, notably perforin and granzyme B. The aim of the present study was to assess whether the granule cytolytic pathway was used by liver-infiltrating CD8+ T lymphocytes. Immunostaining for perforin and granzyme B was performed in 25 patients with chronic hepatitis C, according to the disease activity and their virologic status. Cells stained for perforin and for granzyme B represented 0.15% and 0.10% of the total liver-infiltrating CD8+ T lymphocytes, respectively. Perforin was expressed mainly by activated CD8+ T lymphocytes located in liver lobules. In contrast, granzyme B was expressed mainly by activated CD8+ T lymphocytes located in interface hepatitis and portal tracts. The results were similar in the different groups of patients, whatever the disease activity. In conclusion, this is the first study showing a differential expression of granule components of CD8+ T lymphocytes in the same tissue in vivo. Perforin and granzyme B may be differently expressed by liver-infiltrating CD8+ T lymphocytes, according to their localization in the different specific compartments of the liver, in patients with chronic hepatitis C.     

Noninvasive diagnosis of cellular and antibody-mediated rejection by perforin and granzyme B in renal allografts

A major milestone in transplantation would be the use of biomarkers to monitor rejection. We examined the association between perforin and granzyme-B gene expression detected in the peripheral blood of renal allograft recipients with cellular and antibody-mediated rejection. Furthermore, we judged the appropriateness of assigning negative rejection statuses to persons without a biopsy whose grafts were functioning well clinically. Of the 46 patients who completed the study, recipients with cellular rejection had higher perforin and granzyme-B levels compared with nonrejectors (p = 0.006). Interestingly, recipients with antibody-mediated rejection also had higher perforin and granzyme-B levels compared with nonrejectors (p = 0.04). Patients with high levels of granzyme B had a probability of rejecting that was 26.7 times greater than those patients with low levels of granzyme B. Perforin and granzyme B had sensitivities of 50% and specificities of 95% in predicting rejection (cutoff value = 140). Assigning negative rejection statuses to recipients without a biopsy whose grafts were functioning well did not have a major effect on the direction or significance of covariate values. This study suggests that perforin and granzyme-B gene expressions in peripheral blood are accurate in detecting both cellular and antibody-mediated rejection.     

颗粒酶B和穿孔素免疫组织化学检测诊断肝移植急性排斥反应的敏感性与特异性

目的　探讨颗粒酶B和穿孔素两种免疫活化分子在肝移植急性排斥诊断中的作用,及其与Banff急性排斥反应组织学诊断标准之间的对应关系。方法　在常规组织学诊断基础上,将41份肝穿刺标本用颗粒酶B与穿孔素单克隆抗体进行免疫组织化学EnVision二步法标记,IPP图像分析软件计算阳性细胞数/mm2 作为免疫活化细胞指数(AI),以组织学诊断作为评判有无急性排斥反应的标准。结果　在41份肝穿刺标本中,组织学诊断为急性排斥反应21份,缺乏急性排斥反应组织学改变20份。急性排斥反应组颗粒酶B与穿孔素AI值显著高于无排斥反应组(P<0. 001),中重度排斥反应组AI值显著高于轻度及其非确定性排斥反应组(P<0. 001)。与组织学诊断比较,颗粒酶B的敏感性、特异性、阳性预测值、阴性预测值及诊断一致率分别达到90. 0%、95. 2%、94. 7%、90. 9%以及92. 7%;穿孔素的各指标也分别达到80. 0%以上。结论　颗粒酶B与穿孔素是急性排斥反应免疫效应细胞活化标志,在临床肝移植急性排斥反应时表达明显升高,作为组织学诊断急性排斥反应的辅助指标具有相当高的敏感性及特异性,可用于肝移植后肝穿刺标本的鉴别诊断。     

PFP、GrB真核共表达载体的构建及表达分析

目的：体外扩增出PFP、GrB基因的全片段并构建共表达重组体pVAX1-PIG（即pVAX1-PFP-IRES-GrB）,分析其在人喉癌细胞Hep-2中的表达情况。方法：利用RT-PCR的方法从人的喉癌组织浸润淋巴细胞中扩增全长PFP、GrB的cDNA片段并构建共表达重组体pVAX1-PIG。利用脂质体LipofectamineTM2000将重组真核表达载体pVAX1-PIG转染入人的Hep-2细胞株中,采用RT-PCR、间接免疫荧光法分析其在人Hep-2中的表达情况。结果：经双酶切、测序法证实已成功扩增PFP、GrB基因的全长cDNA,并构建共表达重组体pVAX1-PIG,在荧光显微镜下可见已转染pVAX1-PIG的人Hep-2细胞的胞浆发出苹果绿色荧光。结论：成功扩增PFP、GrB全片段、构建共表达重组体pVAX1-PIG,并在人Hep-2细胞中检测到PFP、GrB蛋白的表达,穿孔素（PFP）/颗粒酶B共同表达能够介导细胞的凋亡,为其在喉癌治疗中的应用研究奠定了基础。     

Involvement of granzyme B and perforin gene expression in the lytic potential of human natural killer cells

Natural killer (NK) cells (CD3⁻) or large granular lymphocytes (LGL) spontaneously kill K562 targets but are unable to kill Daudi cells in the absence of IL-2 stimulation. IL-4 is reported to prevent or inhibit the IL-2-driven lymphokine-activated killer (LAK) generation in NK cells. Therefore, we wished to determine whether the antagonistic effect of IL-4 on IL-2-induced LAK activity might regulate the expression of genes encoding proteins involved in lysis, such as perforin, the pore-forming protein, or which are associated with lysis, such as granzymes A and B. By using in situ hybridization, we showed that, in addition to inducing LAK activity, IL-2 stimulation increased the amount of perforin and granzyme B mRNA at the single-cell level in 40 to 100% of the total CD3⁻ LGL cell population. In addition, our results indicated that the stimulatory effect of IL-2 can be downregulated by IL-4 for both LAK activity and granzyme B and perforin gene expression. Here again, a decrease in the amount of specific mRNA per cell was noted. These findings suggest that modulation of the lytic machinery via lymphokines might be associated with regulation of the lytic potential of NK cells.     

Involvement of granzyme B and perforin gene expression in the lytic potential of human natural killer cells

Natural killer (NK) cells (CD3-) or large granular lymphocytes (LGL) spontaneously kill K562 targets but are unable to kill Daudi cells in the absence of IL-2 stimulation. IL-4 is reported to prevent or inhibit the IL-2-driven lymphokine-activated killer (LAK) generation in NK cells. Therefore, we wished to determine whether the antagonistic effect of IL-4 on IL-2-induced LAK activity might regulate the expression of genes encoding proteins involved in lysis, such as perforin, the pore-forming protein, or which are associated with lysis, such as granzymes A and B. By using in situ hybridization, we showed that, in addition to inducing LAK activity, IL-2 stimulation increased the amount of perforin and granzyme B mRNA at the single-cell level in 40 to 100% of the total CD3- LGL cell population. In addition, our results indicated that the stimulatory effect of IL-2 can be downregulated by IL-4 for both LAK activity and granzyme B and perforin gene expression. Here again, a decrease in the amount of specific mRNA per cell was noted. These findings suggest that modulation of the lytic machinery via lymphokines might be associated with regulation of the lytic potential of NK cells.     

Patients with X-linked lymphoproliferative disease have a defect in 2B4 receptor-mediated NK cell cytotoxicity

Patients with the X-linked lymphoproliferative disorder (XLPD) are unable to control Epstein-Barr virus (EBV)-induced infections and lymphoproliferation. This disease is caused by a deficit of SAP, an adapter protein involved in the signal transduction of several cell surface receptors of the CD2 superfamily. One of these receptors, called 2B4, is expressed on NK cells, cytotoxic T cells and myeloid cells and activates NK cell cytotoxicity. Here we show that XLPD patients have a defect of 2B4 receptor-mediated NK cell cytotoxicity. This defect may contribute to the pathogenesis of XLPD by reducing NK cell lysis of EBV-infected B cells.     

Noninvasive diagnosis of renal-allograft rejection by measurement of messenger RNA for perforin and granzyme B in urine

BACKGROUND: Acute rejection is a serious and frequent complication of renal transplantation, and its diagnosis is contingent on the invasive procedure of allograft biopsy. A noninvasive diagnostic test for rejection could improve the outcome of transplantation. METHODS: We obtained 24 urine specimens from 22 renal-allograft recipients with a biopsy-confirmed episode of acute rejection and 127 samples from 63 recipients without evidence of acute rejection. RNA was isolated from the urinary cells. Messenger RNA (mRNA) encoding the cytotoxic proteins perforin and granzyme B and a constitutively expressed cyclophilin B gene were measured with the use of a competitive, quantitative polymerase chain reaction, and the level of expression was correlated with allograft status. RESULTS: The log-transformed mean (+/-SE) levels of perforin mRNA and granzyme B mRNA, which encode cytotoxic proteins, but not the levels of constitutively expressed cyclophiiin B mRNA, were higher in the urinary cells from the 22 patients with a biopsy-confirmed episode of acute rejection than in the 63 recipients without an episode of acute rejection (perforin, 1.4+/-0.3 vs. -0.6+/-0.2 fg per microgram of total RNA; P<0.001; and granzyme B, 1.2+/-0.3 vs. -0.9+/-0.2 fg per microgram of total RNA; P<0.001). Analysis involving the receiver-operating-characteristic curve demonstrated that acute rejection can be predicted with a sensitivity of 83 percent and a specificity of 83 percent with the use of a cutoff value of 0.9 fg of perforin mRNA per microgram of total RNA, and with a sensitivity of 79 percent and a specificity of 77 percent with the use of a cutoff value of 0.4 fg of granzyme B mRNA per microgram of total RNA. Sequential urine samples were obtained from 37 patients during the first nine days after transplantation; and measurements of the levels of mRNA that encoded cytotoxic proteins identified those in whom acute rejection developed. CONCLUSIONS: Measurement of mRNA encoding cytotoxic proteins in urinary cells offers a noninvasive means of diagnosing acute rejection of renal allografts.     

PFP、GrB的共表达杀伤人喉癌Hep-2细胞的体外研究

为探讨穿孔素(PFP)、颗粒酶B(GrB)共表达对人喉癌(Hep-2)细胞生长的抑制及其诱导该细胞的凋亡作用,采用RT-PCR的方法从人的喉癌组织浸润淋巴细胞中扩增全长PFP、GrB的cDNA片段,构建共表达重组体pVAX1-PIG,并将其转染入人的Hep-2细胞株中。收集转染后的Hep-2细胞,采用软琼脂集落形成实验、MTT法、原位末端标记法(TUNEL)、流式细胞仪(FCM)检测分析各组人Hep-2细胞的生长抑制及其凋亡情况。结果显示pVAX1-PIG转染组的集落形成数目比空白对照组与pVAX1转染组明显减少(P<0.05),MTT检测结果显示对照组细胞生长速度比pVAX1-PIG转染组要快。TUNEL染色、FCM法检测均显示pVAX1-PIG转染组的Hep-2细胞大量凋亡且其凋亡率显著高于对照组(P<0.05)。因此,PFP、GrB的共表达能够抑制人Hep-2细胞的生长并且可以诱导该细胞的凋亡。     

Surface Ly-5 glycoprotein in murine natural killer (NK) cell development, target binding and cytotoxicity

The role of surface Ly-5 glycoprotein expression in the binding and lysis of susceptible tumor targets by natural killer cells was studied using NK cell-enriched splenocytes from 6-8 week old C57BL/6 mice which were reacted with anti-Ly-5 serum in the presence or absence of a source of complement. A conjugate assay was used to demonstrate that abrogation of tumor cell lysis by anti-Ly-5 serum involved the inhibition of NK cell binding to susceptible YAC-1 targets. Additionally, reconstituted membrane vesicles from NK cell-enriched splenocyte populations blocked binding of effector cells to YAC-1 lymphoma targets, a phenomenon which was abrogated by pretreatment of vesicles with anti-Ly-5 serum. Indirect immunofluorescent labeling and cell sorting were used in the physical separation of Ly-5+ and Ly-5- cells to examine the effect of interferon and interleukin preparations on Ly-5 expression and Nk activity. Three hour treatment of sorted Ly-5- cells with murine alpha + beta interferon resulted in conversion of 22% of the cells to an Ly-5+ phenotype, as well as a significant increase in the percent specific lysis of NK-susceptible YAC-1 targets when compared to freshly sorted Ly-5- cells (29.5 +/- 1.9 vs 2.6 +/- 4.0; p less than .001). In vitro proliferation of sorted Ly-5- cells was induced by three week culture in an interferon- and interleukin-containing supernatant from ConA stimulated BALB/c splenocytes (CM), followed by repeat analysis of Ly-5 expression and cytotoxic activity. Cell sorter purified Ly-5- cells cultured in CM acquired substantial surface Ly-5 with concomitant high levels of cytotoxic activity that remained partially susceptible to inhibition by anti-Ly-5 serum. The data presented suggest that surface Ly-5 glycoprotein expression is important for binding of freshly isolated NK cells to YAC-1 targets. In addition, Ly-5- precursors of NK cells are present in murine splenic tissues and can be induced by CM to become highly active effector cells with increased surface Ly-5 expression. The persistent susceptibility of a subset of these cells to inhibition of cytotoxic activity by anti-Ly-5 serum provides additional evidence of an important role for the Ly-5 glycoprotein in the natural killer cell cytolytic mechanism against certain targets.     

Differential expression of granzyme A and granzyme B proteases and their secretion by fresh rat natural killer cells (NK) and lymphokine-activated killer cells with NK phenotype (LAK-NK).

Granzymes A-G are a family of serine proteases localized in the cytoplasmic granules of cytotoxic T lymphocytes (Masson, D. et al. Cell 1987. 49: 679) and granzyme A is secreted by T lymphocytes in response to antigenic stimulation. Granzyme A is also expressed by natural killer (NK) and lymphokine-activated killer (LAK) cells. Here we show that fresh rat NK cells constitutively express granzyme B and that granzyme A and granzyme B are differentially regulated in unstimulated NK cells vs. LAK cells with NK phenotype (LAK-NK cells). We also show that both granzymes A and B are secreted in a calcium-dependent manner, by NK and LAK-NK cells in response to stimuli which trigger NK cell functions.     

Modulation by suramin of NK and monocytic cell-mediated cytotoxicity in human and murine cells

The in vitro effects of suramin, a compound recently tested in AIDS treatment, were investigated on human and murine NK and monocyte macrophage cytotoxicity and monocyte migratory ability. In a short-term, TNF-dependent assay, pre-exposure (4-18 h) to 100-400 micrograms/ml suramin was associated with a markedly increased cytotoxicity by human monocytes and murine-elicited peritoneal macrophages, paralleled by a greater cytotoxic capacity in the supernates of these effectors. Preincubation with the same pharmacological suramin concentrations also resulted in enhanced spontaneous and directed migration in monocytic cells. Suramin-preincubated human PBL and murine splenocytes were unchanged in their basal NK cytotoxicity but exhibited a deficient response to IFN. Pre- and post-incubations with suramin resulted in increased macrophagic cytotoxicity for TNF-insensitive targets. Conversely, postincubation of effectors with the drug at 100-400 micrograms/ml was associated with profound decreases in both NK and TNF-mediated macrophagic cytotoxicities, and prior exposure to suramin of macrophagic supernates resulted in reduced cytotoxic activity. The mechanisms involved in the complex modulatory activity of suramin for monocyte macrophages and NK cells and the possible therapeutic implications of these findings are discussed.