Gestational Age Correlates With Immunosuppressive Properties of Hydatidiform Mole Pregnancies

PROBLEM: Soluble trophoblast extracts (HME) from some human hydatidiform mole pregnancies suppress IL-2-dependent T-cell proliferation, while others express no immunosuppressive bioactivity. This study was designed to determine if suppression by HME was correlated with gestational age, uterine size, or hCG secretion. METHOD: Soluble extracts were prepared from nine hydatidiform mole trophoblast samples and screened for immunosuppressive activity using a murine cytotoxic T-cell proliferation assay (CTLL-2). Gestational ages were determined from last menstrual cycle and uterine size was estimated at the time of surgery. Serum samples were collected prior to uterine evacuation and were assayed for human chorionic gonadotropin (hCG). RESULTS: Four of nine HME samples significantly (P < 0.05) suppressed CTLL2 proliferation, while five exhibited no suppressive activity. A strong positive correlation (r = 0.639) was noted for the relationship between gestational age of the molar pregnancies and interleukin-2(IL-2)-stimulated CTLL2 proliferation (expressed as % of control) in the presence of HME (500 μg/mL). This indicates that HME suppression of CTLL2 proliferation is highest in early gestation and then declines with increasing gestational age. A similar correlation was observed between estimated uterine size at surgery and CTLL2 proliferation with added HME, although the association was not as strong (r = 0.359). No association was noted between hCG levels and CTLL2 proliferative responses (r = ?0.091). CONCLUSIONS: The results of this study suggest that production of immunosuppressive factors by hydatidiform mole trophoblast is developmentally regulated, and decreases with advancing gestation.     

Immunosuppression by Hydatidiform Mole Trophoblast Is Neutralized by Monoclonal Antibodies to β-Interferon

PROBLEM: In sheep and cattle, trophoblast-derived interferons serve as signals for the maternal recognition of pregnancy and may regulate the immunologic relationship between the fetus and mother. METHOD: In this study, soluble extracts prepared from human hydatidiform mole decidua (DE) and trophoblast (HME) were screened for immunosuppressive activity using an interleukin (IL)-2-dependent T-cell line (CTLL2). Antibody neutralization studies were performed with monoclonal antibodies to α- and β-interferon (IFN). RESULTS: HME suppressed (P < 0.05) IL-2-stimulated (2 IU/well) CTLL2 proliferation at doses ranging from 500 (52 ± 2% of control) to 100 (74 ± 5%) μg/ml concentrations. DE also suppressed (P < 0.05) CTLL2 proliferation in a dose-related fashion from 500 (20 ± 6% of control) to 100 (71 ± 8%) μg/ml doses. Preincubation with the α- and β-IFN antibody preparations had no effect on CTLL2 suppression by the DE sample. In contrast, the β-IFN antibody partially neutralized the suppressive activity of HME at each of the dilutions tested. The monoclonal antibody to α-IFN failed to neutralize HME suppression at any of the doses tested. CONCLUSIONS: These results suggest that hydatidiform mole trophoblast produces a β-IFN-like macromolecule that may abrogate maternal rejection responses that are harmful to the developing fetal allograft.     

Hydatidiform mole pregnancy trophoblast extracts differentially suppress interleukin-2-induced proliferation of human T-lymphocytes and PHA-blasts

Immunoregulatory factors of trophoblast origin may partially abrogate maternal immune responses to the fetus during pregnancy. We have previously shown that soluble factors extracted from hydatidiform mole trophoblast suppress interleukin-2 (IL-2)-dependent proliferation of a cloned murine cytotoxic T cell line (CTLL-2). To characterize human T cell responses to this trophoblast extract, we measured the effects of molar tissue extracts (HME) on IL-2-stimulated proliferation of human T-lymphocytes and mitogen (PHA) transformed T-cell blasts (PHA-blasts). HME significantly (P less than 0.05) suppressed T-lymphocyte proliferation in response to 5 and 10 units/ml of IL-2 at 500 and 250 micrograms/ml, while no effect was observed at the 100 micrograms/ml concentration. Suppression by HME of IL-2-stimulated T-cell proliferation was partially overcome by the addition of excess IL-2. HME also suppressed (P less than 0.05) IL-2-stimulated proliferation of PHA-blasts at 500 and 250 micrograms/well at both 5 and 10 units/ml of IL-2. As observed with resting T-cell responses, no suppression of PHA-blast proliferation was observed using 100 micrograms/ml of HME. In contrast to the response of the resting T-cells to excess IL-2, HME suppression of IL-2-stimulated blast proliferation was not affected by increasing the concentration of IL-2. These results indicate that extracts from hydatidiform mole trophoblast contain immunosuppressive factors that block human T-cell clonal expansion by inhibiting the utilization and/or production of IL-2. Furthermore, the effects of HME are not reversed by excess IL-2 when PHA-blasts are reacted compared to resting T-cell responses, which are partially reversed in the presence of excess IL-2.(ABSTRACT TRUNCATED AT 250 WORDS)     

Comparison of Immunosuppressive Properties of Hydatidiform Mole Decidua and Trophoblast Extracts

PROBLEM: The immunologic privilege afforded the fetus relies upon immunoregulation within the maternal-fetal interface. Trophoblast and decidua-derived immunoregulatory factors enforce this privilege by locally suppressing maternal responses to trophoblast antigens. The relative contribution of trophoblast or decidua immunosuppressive factors to pregnancy immunotolerance are not well characterized. The purpose of this study was to compare the suppressive effects of hydatidiform mole trophoblast and decidua extracts on interleukin-2-dependent proliferation. METHOD: Tissue extracts were prepared from hydatidiform mole trophoblast and decidua following uterine evacuation. Samples were submitted to interleukin-2-dependent and -independent cell proliferation assays. RESULTS: Hydatidiform mole trophoblast extract significantly (P < 0.05) suppressed interleukin-2-dependent proliferation but did not affect interleukin-2-independent cell proliferation. In contrast, molar decidua extract suppressed both cell lines. CONCLUSIONS: Human hydatidiform mole trophoblast contains factor(s) that specifically abrogate interleukin-2-dependent clonal expansion of murine cytotoxic T-cells. In contrast, extracts of molar decidua suppressed both interleukin-2-dependent and -independent responses. This indicates that the trophoblast antagonizes critical interleukin-2-mediated immunologic responses, but that the decidua uses nonspecific antiproliferative mechanisms for immunoregulation.     

酵母菌重组白细胞介素2生物学活性鉴定

利用IL-2依赖细胞系CTLL检测酵母菌系统表达的人rIL-2生物活性。结果证实,酵母菌 rIL-2 能明显刺激 CTLL细胞的生长。用进口的 rIL-2作为标准,测定所表达的 rIL-2活性单位为 33u/ml。单克隆抗体中和实验证实,酵母菌 rIL-2 能特异地和天然 IL-2单抗结合,抑制其本身诱导的 CTLL细胞增殖。这种抑制是由 IL-2单抗参与的,因为鼠正常血清没有这种抑制作用。此外,经蛋白A 柱层析纯化后的单抗在 0.27μg/孔时就能表现明显地抑制,提示该抗原抗体反应的特异性和专一性。     

用经氢化可的松处理的小鼠胸腺细胞测定白细胞介素2

白细胞介素2(IL-2)是重要的免疫调节因子。对IL-2的检测,国外一般采用依赖IL-2的T细胞株CTLL细胞进行测定。该细胞在国内来源困难,不易维持。国内亦有用鼠胸腺细胞增殖试验来测定IL-2者,但由于不能消除IL-1的非特异影响,因此,该方法受一定局限。本文参照Christine的报道,用经Con-A(4μg/ml)诱导及氢化可的松(0.04μg/ml)处理的鼠胸腺细胞(HCIT)进行IL-2测定,并同时用CTLL-2细胞测定方法进行比较,结果证实:用HCIT细胞测定IL-2与用CTLL-2细胞测定两种方法有很好的相关性、相关系数r=0.94。但用CTLL细胞比用HCIT细胞较敏感。在本试验条件下,前者敏感量为0.4IL-2活性单位,后者为1.3IL-2活性单位。因此用HCIT细胞进行IL-2测定,也可以达到特异(对IL-1不发生反应),灵敏、重复性好的效果。且由于胸腺细胞容易获取,操作技术简便、易于掌握,是一种在没有CTLL细胞情况下测定IL-2的较好的方法。     

Human amniotic fluid lacks interleukin-2 and interleukin-15 but can interact with the beta-chain of the interleukin-2 receptor

The present study investigated whether an explanation for the conflicting reports on the interleukin-2 (IL-2) status of amniotic fluid is due to the presence of IL-15 which shares biological activities with IL-2 and utilizes the IL-2 receptor beta-chain. Amniotic fluids from 45 normally progressing pregnancies between 14 and 16 weeks after the last menstrual period were assayed for IL-2 and IL-15 by bioassay and enzyme-linked immunosorbent assay (ELISA). The ability of amniotic fluids to induce cytotoxic T lymphoblastoid line-2 (CTLL-2) cell proliferation was demonstrated to be dependent upon bioassay culture conditions. In serum-free medium each amniotic fluid stimulated CTLL-2 proliferation with a mean level of IL-2-like bioactivity of 14.7 +/- 2.3 ng/ml but amniotic fluids failed to induce CTLL-2 proliferation in serum-supplemented medium. Treatment with neutralizing anti-IL-2 or anti-IL-15 antibodies failed to inhibit amniotic fluid-induced CTLL cell proliferation in serum-free medium, indicating a lack of IL-2 and IL-15 bioactivity. In contrast, treatment with anti-IL-2 receptor beta-chain antibody significantly reduced amniotic fluid-induced proliferation. The lack of IL-2 and IL-15 activity in amniotic fluids was confirmed using ELISA. Although high levels of IL-15 immunoactivity were detected in all samples, specificity controls showed a lack of specific IL-15 immunoactivity in amniotic fluid. Pretreatment of amniotic fluids with 100-500 ng/ml mouse immunoglobulin G abrogated IL-15 immunoactivity, indicating that amniotic fluid contains molecules binding to Fc regions of immunoglobulins and responsible for false ELISA positivity. These studies unequivocally show that amniotic fluid lacks IL-2 and IL-15 but can stimulate CTLL-2 cell proliferation via the IL-2 receptor beta-chain. The absence of IL-2 and IL-15 in normal mid-trimester amniotic fluid suggests that the cytokine profile of human pregnancy appears to be associated with a bias against type 1 cytokines within the feto-placental unit.     

恶性葡萄胎患者化疗前后血清IL-2、SIL-2R和外周血B细胞和T淋巴细胞亚群检测的临床意义

目的:探讨了恶性葡萄胎患者化疗前后血清IL-2、SIL-2R和外周血B细胞及T淋巴细胞亚群水平及临床意义.方法:分别应用放射免疫分析、ELISA法和单克隆抗体法对32例恶性葡萄胎患者进行了血清IL-2、SIL-2R和外周血B细胞及T淋巴细胞亚群进行了检测,并与35名正常健康人作比较.结果:恶性葡萄胎患者在化疗前血清SIL-2R和B细胞数均非常显著地高于正常人(P＜0.01),而IL-2、CD3、CD4、CD4/CD8比值则显著地低于正常人组(P＜0.01),经化疗后6个月,与正常人比较仍有显著性差异(P＜0.05).结论:恶性葡萄胎患者是一种自身调节免疫异常的疾病.     

Anti-CD3 antibody-induced expression of both p55 and p75 chains of the high affinity interleukin-2 receptor on human T lymphocytes is inhibited by cyclosporin A.

The inhibitory effect of cyclosporin (CsA) was investigated on human lymphocytes stimulated by anti-T-cell antibodies (anti-CD3 and -CD2) or mitogenic lectins. Whereas inhibition of cell proliferation (50%) occurred at 10 ng/ml CsA after cell activation via CD3 or CD2, higher CsA concentrations (300 ng/ml) were necessary to inhibit lectin-mediated cell activation (PHA, Con A). Exogenous recombinant interleukin-2 (rIL-2) partially reversed the inhibitory effect on antibody-stimulated cells only; however, at higher CsA concentrations (300 ng/ml) proliferation was again inhibited. Thus, CsA affected IL-2R expression and/or function at higher concentrations (300 ng/ml). CsA had no effect on receptor function as measured on IL-2-dependent cell growth of CTLL cells or preactivated lymphocytes. However, CsA inhibited both high and low affinity receptor expression as shown by [125I]IL-2 equilibrium binding studies on anti-CD3-stimulated cells. Cross-linking studies revealed that both p55 (TAC) and p75 chains of the IL-2R were not induced at low CsA concentrations (10 ng/ml). However, addition of rIL-2 reversed CsA inhibition of IL-2R expression. It is concluded that CsA, at least in anti-CD3-stimulated cells, inhibits IL-2R expression and cell proliferation with similar potency. Exogenous rIL-2 reverses CsA inhibition of IL-2R expression. This might be due to binding of rIL-2 to receptors which escape CsA inhibition, thereby up-regulating receptor expression which is drug resistant.     

Methyl inosine monophosphate (MIMP) augments T-lymphocyte mitogen responses and reverses various immunosuppressants

Methyl inosine monophosphate (MIMP) augments preferentially the in vitro responses of human and murine lymphocytes to a T-cell mitogen such as phytohemagglutinin (PHA) and inconsistently to a B-cell mitogen such as pokeweed or lipopolysaccharide (LPS). In a normal interleukin-2-dependent cell line (CTLL), MIMP showed little or no effect on IL-2 action; however, in a murine CTLL line exhibiting impaired responses to IL-2, MIMP stimulated thymidine incorporation and restored the response to IL-2. MIMP augments the PHA responses of both CD4⁺ and CD8⁺ human peripheral blood T-cells. The effect of MIMP to augment the PHA response of human lymphocytes is paralleled by the parent molecule, IMP. MIMP, but not IMP, is resistant to hydrolysis by 5'nucleotidase; thus, MIMP appears to be a protected analogue of IMP which is capable of in vivo action. MIMP (100 μg/ml) augments the PHA responses of 15 of 24 elderly humans. MIMP also augments the PHA responses of eight HIV-infected pre-AIDS patients but not of eight AIDS patients. When PHA responses of human lymphocytes are suppressed in vitro by an HIV-derived immunosuppressive peptide, interferon α, or prostaglandin PGE₂, MIMP (0.1–100 μg/ml) progressively restores the depressed response; however, when the suppression is severe (greater than 50%), MIMP cannot restore the response. These data indicate that MIMP potentiates normal T-lymphocyte mitogen responses and restores those impaired by a variety of inflammatory and immunosuppressive influences.     

PCNA和Caspase-3在妊娠滋养细胞疾病中的表达及意义

目的研究PCNA和Caspase-3在妊娠滋养细胞疾病中的表达变化及意义,为妊娠滋养细胞疾病早期诊断、预后判断提供理论依据。方法收集滋养细胞疾病标本50例,其中葡萄胎10例(均为完全性葡萄胎),侵蚀性葡萄胎20例,绒毛膜癌20例。正常早孕绒毛标本10例为对照组。应用免疫组织化学技术检测PCNA和Caspase-3在早孕绒毛、葡萄胎、侵蚀性葡萄胎、绒毛膜癌组织中的表达情况。结果 PCNA在正常早孕绒毛、葡萄胎、侵蚀性葡萄胎和绒癌中的表达分别为10.24%、20.70%、50.92%、53.65%,各组差异有统计学意义(P0.05)。Caspase-3在正常早孕绒毛、葡萄胎、侵蚀性葡萄胎和绒癌中的表达先升高又降低,分别为1.25%、2.60%、6.40%、1.90%,各组差异有统计学意义(P0.05)。结论 PCNA及Caspase-3表达异常,增殖/凋亡失衡是引起GTT的重要因素。     

滋养细胞肿瘤DNA图像定量分析

目的:探讨图像分析技术对滋养细胞肿瘤DNA定量分析的应用价值.方法:应用图像分析技术对33例滋养细胞肿瘤细胞核DNA含量进行了定量测定和比较.结果:从正常绒毛→良性葡萄胎→恶性葡萄胎→绒毛膜癌:DNA含量和非整倍体细胞呈增高趋势.恶性葡萄胎和绒毛膜癌明显高于良性葡萄胎和正常绒毛,有显著性差异(P<0.01).良性葡萄胎高于正常绒毛,但两者相比无显著性差异(P>0.05).绒毛膜癌高于恶性葡萄胎,但两者相比亦无显著性差异(P>0.05).结论:图像分析仪对滋养细胞肿瘤DNA定量分析,可对该肿瘤的诊断、化疗、预后提供重要信息.     

Increased interleukin-2 level in patients with primary hypothyroidism.

The effects of hypothyroid status in humans on cytokine blood levels have been studied. Evaluations of interleukin-1 beta (IL-1 beta), interleukin-2 (IL-2), thyrotropin, thyroxine, and triiodothyronine were performed in seven patients with primary hypothyroidism and eight euthyroid healthy control subjects on the basis of venous blood samples collected after an overnight rest. A normal level of IL-1 beta (23 +/- 15 fmol/ml) and an increased IL-2 level (82 +/- 56 fmol/ml) have been shown in hypothyroid patients versus controls (IL-1 beta, 24 +/- 5 fmol/ml; IL-2, 33 +/- 13 fmol/ml). The possible role of thyroid hormones and of an autoimmune mechanism in the link with increased IL-2 blood level in hypothyroidism in man have been discussed.     

A macrophage-derived factor induced by alpha 1-acid glycoprotein that inhibits IL-1 comitogenic activity

After exposure to a concanavalin A (Con A)-unreactive variant of alpha 1-acid glycoprotein (AGP), macrophages released an inhibitor of interleukin-1 (IL-1) proliferative activity in the thymocyte comitogenic assay. This effect was observed with AGP concentrations above 100 micrograms/ml in the macrophage supernatant and would appear to be mediated by the macrophages, since native AGP had no activity on thymocyte proliferation. Preliminary physicochemical characterization showed that the factor was partially resistant to heating, undialyzable, and eluted with an apparent molecular mass of 50-100 kDa when subjected to Sephacryl S-200 chromatography. Murine IL-1 and human (h) recombinant (r) IL-1 were affected by this factor to the same extent. IL-1 and IL-2 co-induced thymocyte proliferation, which is mitogen-independent, was also inhibited, whereas hrIL-2 activity was not suppressed when assayed in thymocytes with PHA at a submitogenic concentration or in CTLL cells. The factor did not interfere with TNF alpha or hrIL-6 activity when tested against their specific cell line. These data indicate that the inhibitor may act specifically against IL-1 activity and further elucidate the possible role of AGP in the modulation of IL-1 activity via the secretion of an inhibitor.     

Increased laminin-1 expression in hydatidiform mole

To investigate the aetiology of hydatidiform mole, laminin-1 expression was determined in human villous tissues obtained from normal pregnancies (n = 17) and complete hydatidiform moles (n = 10). Indirect immunofluorescent staining was performed to detect laminin-1, and Northern blot analysis was performed to assess expression of laminin mRNA. Serum concentrations of laminin P-1 were also measured. Immunohistochemical analysis revealed stronger staining of the trophoblastic basement membrane in hydatidiform mole than in normal pregnancy. Northern blot analysis revealed that villous expression of laminin mRNA was significantly increased in hydatidiform mole compared with normal pregnancy (P < 0.05). The serum laminin P-1 concentration was also significantly higher in those patients with hydatidiform mole than in normal pregnancy (P < 0.05). These results suggest that laminin- 1 might play an important role in determining the pathophysiology and structure of hydatidiform mole. In addition, measurement of serum laminin P-1 in combination with human chorionic gonadotrophin might be useful in the diagnosis of hydatidiform mole, to evaluate the prognosis, and to detect the presence of metastatic or recurrent disease.      

Use of a human minichromosome as a cloning and expression vector for mammalian cells.

A natural human minichromosome (MC1) derived from human chromosome 1 was shown to be linear and to have a size of 5.5 Mb. Human IL-2 cDNA and the neo gene were co-transfected into a MC1-containing human-CHO hybrid cell line. Integration of the foreign genes was directed to the pericentromeric region of MC1 by co-transfection of chromosome 1-specific satellite 2 DNA. A number of G418-resistant transfectants were obtained and expression of IL-2 was determined. FISH analysis demonstrated co-localization in the minichromosome of the IL-2 gene and of the satellite 2 DNA. An IL-2-producing clone was used in cell fusion experiments with IL-2-dependent murine CTLL cells to generate CTLL-human hybrids containing the modified minichromosome (MC1- IL2 ). The hybrids were able to grow in medium lacking IL-2 for 17 mean population doublings (MPD), indicating that expression of the cytokine was sufficient to relieve the IL-2 dependence of CTLL proliferation. Endogenous IL-2 production delayed the onset of apoptosis in the IL-2-dependent CTLL cells. Mitotic stability was shown to be 100% in the human-CHO hybrids and 97% per MPD in CTLL cells. These results demonstrate that a natural human minichromosome can be utilized as a cloning and expression vector for mammalian cells and that the MC1 minichromosome can be engineered to deliver IL-2 to two types of cells, fibroblasts and lymphocytes.     

High Serum-Soluble Interleukin-2 Receptor is not Associated with the Immunosuppression in Diffuse Cutaneous Leishmaniasis

Diffuse Cutaneous Leishmaniasis (DCL) is a rare complication of Leishmania aethiopica -induced cutaneous leishmaniasis which is associated with non-self healing and in vivo and in vitro antigen-specific non-responsiveness. Such antigen-specific unresponsiveness is also observed in visceral leishmaniasis (VL). The non-responsiveness seen in VL disease is believed to be due, in part, to serum-derived factors, including raised serum soluble IL-2 receptor (sIL-2R). Raised sIL-2R in serum was not a consistent feature of DCL in our study (range: 787–4546 U/ml) but was frequently observed in sera of patients with other dermatological disorders (range: 474–3313 U/ml) and some patients with the simple local cutaneous leishmaniasis (LCL; range: 556–4247 U/ml). The level of sIL-2R in the sera of DCL patients was not indicative of the disease state. Sera from DCL patients did not reduce proliferation of the IL-2-dependent CTLL cell line nor reduce PHA-driven mononuclear cell proliferation, although sera from VL patients could. Both DCL and VL sera could reduce the L. aethiopica -driven proliferation. Furthermore addition of serial dilutions of recombinant IL-2 to CTLL cultured in VL or DCL sera containing high sIL-2R levels did not alter the effect of such sera on proliferation. We conclude therefore, that raised sIL-2R in serum is not associated with the immunosuppression in DCL.     

Interaction of immune and connective tissue cells: I. The effect of lymphokines and monokines on fibroblast growth

In order to determine if mononuclear cells may be secreting factors capable of modulating fibroblast growth, the in vitro proliferative response of fibroblasts to cytokines known to be secreted by mononuclear cells was measured, using both growth arrested and proliferating cells. Of the cytokines tested, which included interleukin-1 (IL-1), interleukin-2 (IL-2), interleukin-3 (IL-3), interleukin-4 (IL-4), interleukin-6 (IL-6), interferon-alpha (IFN-alpha), interferon-gamma (IFN-gamma), transforming growth factor-alpha (TGF-alpha), transforming growth factor-beta (TGF-beta), platelet derived growth factor (PDGF), and tumor necrosis factor-alpha (TNF-alpha), only TNF-alpha and PDGF had demonstrable growth factor activity. Neither IL-1 alpha nor beta showed any true growth factor activity but were able to enhance the replication of already proliferating cells. No inhibition of proliferation was noted by any of the cytokines with the exception of TNF-alpha and TGF-beta. TNF-alpha in doses greater than 500 ng/ml caused fibroblast death, probably by a prostaglandin related mechanism as fibroblasts remained viable, although non proliferative, when assayed in the presence of indomethacin, a known inhibitor of prostaglandin E2 (PGE2) synthesis. TGF-beta was inhibitory to proliferation at doses greater than 100 ng/ml, while fibroblasts remained viable. This effect was not influenced by indomethacin and hence is unlikely to be PGE2 related.     

Biological activity of interleukin-2 bound to Candida albicans.

The lymphokine interleukin-2 (IL-2), which is necessary for the generation of an optimal cell-mediated immune response, has recently been shown to have lectinlike properties, with specificity for high-mannose groups. Therefore, the ability of IL-2 to bind to the mannose-rich fungus Candida albicans was examined. Heat-killed fungi preincubated with IL-2 stimulated, in a dose-dependent manner, proliferation of the IL-2-dependent cell line CTLL20. Soluble mannan, which is rich in exposed mannose groups, inhibited binding of IL-2 to C. albicans by approximately 60%, suggesting that the lectinlike properties of IL-2 are partially responsible for its fungal binding capacity. Binding of IL-2 to fungi appeared to be reversible, as C. albicans preincubated with IL-2 stimulated CTLL20 proliferation even when the fungi and cells were separated by an 0.4-microns-pore-size membrane. The lymphoproliferative response of normal human peripheral blood mononuclear cells to C. albicans was augmented when the fungus was preincubated with IL-2. Binding of 125I-IL-2 could not be inhibited by unlabeled IL-2, suggesting the absence of high-affinity receptors on C. albicans for IL-2. While the in vivo relevance remains to be determined, these data demonstrate that IL-2 can bind to C. albicans in vitro and thereby influence the host response to this medically important fungus.