脂多糖结合蛋白在脓毒症患者诊断和预后预测中的作用

目的:探讨脂多糖结合蛋白(LBP)在脓毒症患者诊断和预后预测中的作用。方法:挑选ICU的患者共80名,患者分为全身炎症反应综合征(SIRS)组(阴性对照组)、脓毒症存活组和脓毒症死亡组;所有患者均于进入ICU后24 h内采集血清样本并进行APACHEⅡ评分分析;另挑选10名健康志愿者血清作为正常对照组;ELISA检测各组样本血清LBP、C反应蛋白(CRP)和降钙素原(PCT)浓度;并以APACHEⅡ评分、血清LBP、CRP和PCT浓度对脓毒症诊断和预后预测做ROC曲线,评价LBP在脓毒症患者诊断和预后预测中的作用。结果:与SIRS组相比,脓毒症组的APACHEⅡ评分、血清LBP、CRP、PCT浓度均升高(P0.05);与脓毒症存活组相比,死亡组的APACHEⅡ评分和血清LBP浓度升高(P0.05),而血清CRP和PCT浓度在脓毒症存活组与死亡组之间的差异无统计学意义;LBP血清浓度高于26.84 mg/L时诊断脓毒症的敏感性和特异性分别为97.1%和95.9%;LBP血清浓度高于54.16 mg/L时预测脓毒症预后的敏感性和特异性分别为85.2%和80.0%。结论:与传统的脓毒症生物标志物CRP、PCT相比,LBP在脓毒症的诊断和预测方面都具有更好的效果。     

Increased distribution and expression of CD64 on blood polymorphonuclear cells from patients with the systemic inflammatory response syndrome (SIRS)

Evidence is growing to suggest that the multiple organ damage of the systemic inflammatory response syndrome (SIRS) arises from the untoward activity of blood polymorphonuclear cells (PMNs), which upon activation acquire the IgG high affinity receptor, CD64. In the current study, flow cytometry was used to assess the prevalence of CD64-bearing PMNs and the intensity of expression of CD64 in whole blood samples from 32 SIRS patients, 11 healthy normal subjects and from eight non-SIRS patients in the intensive care unit (ICU). The percentage of PMNs expressing CD64 was higher in SIRS patients (mean 65%) than in non-SIRS patients (mean 42%; P < 0.02) and in healthy controls (mean 19%; P < 0.001) and was particularly evident in patients with SIRS and sepsis (mean 71%; P < 0.02) as opposed to SIRS alone (mean 55%). There were more CD64 molecules expressed on PMNs from patients with SIRS (median 1331 molecules/cell) in comparison with PMNs from healthy subjects (median 678 molecules/cell; P < 0.01). The highest intensity of CD64 expression was associated with PMNs from patients with both SIRS and sepsis. Functional studies revealed that the supranormal binding of PMNs from patients with SIRS to endothelial monolayers treated with TNFalpha was impeded by anti-CD64 antibodies (mean 24% inhibition; P < 0.01). Monitoring the distribution of CD64+ PMNs and their level of CD64 expression could be of assistance in the rapid discrimination of patients with SIRS from other ICU patients and in the identification of PMNs which are likely to participate in the pathological manifestations of the disease.     

脑外伤患者检测血浆IL-11的临床评价

目的：揭示脑外伤患者血浆白介素-11（IL-11）浓度的变化,探讨其在脑损伤中的作用及对预后的预测价值。方法：收集重型脑外伤患者作为脑外伤组,共112例。收集同期健康体检正常人作为正常对照组,共40例。正常对照组静脉血体检时获得。脑外伤组静脉血在入院时获得。ELISA测定血浆IL-11浓度。结果：脑外伤后1个月内死亡31例（27.7%）。血浆IL-11浓度（25.8±10.4）pg/ml显著高于正常对照组（10.9±3.2）pg/ml（P〈0.001）。入院时GCS评分与血浆IL-11浓度呈显著负相关（r=-0.616,P〈0.001）。Logistic回归分析显示,入院时血浆IL-11浓度（OR=1.231,95%CI=1.110～1.349,P〈0.01）是脑外伤后1个月内死亡的危险因素。ROC曲线分析显示,血浆IL-11浓度预测脑外伤后1个月内死亡有显著预测价值（曲线下面积=0.798,95%CI=0.704～0.875,P〈0.001）,且判定血浆IL-11浓度截止值为27.4pg/ml,对预测脑外伤后1个月内死亡有80.7%的灵敏度和74.1%的特异度。结论：脑外伤后血浆IL-11浓度升高,可能参与脑损伤的炎症反应,临床检测这个指标有助于早期判断脑外伤患者的预后。     

血浆抵抗素浓度与脑外伤预后的相关性研究

目的:揭示脑外伤患者血浆抵抗素浓度,分析其与预后的相关性.方法:收集重型脑外伤患者作为脑外伤组,共108例.收集同期健康体检人群作为对照组,共40例.对照组静脉血体检时获得.脑外伤组静脉血在入院时获得.ELISA测定血浆抵抗素浓度,统计分析其与预后的相关性.结果:脑外伤患者入院后1个月内死亡28例(25.9%).脑外伤...     

侵袭性牙周炎患者血浆β-防御素-2的检测及临床意义

目的:揭示侵袭性牙周炎患者血浆β-防御素-2浓度的变化,探讨其与侵袭性牙周炎患病危险性的相关性.方法:收集侵袭性牙周炎患者作为牙周炎组,共56例.收集同期牙周健康者作为对照组,共35例.ELISA检测血浆β-防御素-2浓度.统计分析其与侵袭性牙周炎患病危险性的相关性.结果:协方差分析显示,牙周炎组血浆β-防御素-2浓度...     

Clinical and immunologic observations in patients who stop venom immunotherapy

It is currently recommended that venom immunotherapy (VIT) be continued as long as the sensitivity persists (indicated by positive venom skin tests or RAST). In this pilot study, we performed a retrospective survey of the clinical and immunologic effects of stopping VIT. The 82 patients studied had received maintenance VIT for a mean of 14 months and had stopped VIT a mean of 43 months before evaluation. Subsequent "field" stings in 28 patients caused systemic reactions in six cases (22%), which is significantly higher than the 1% to 3% systemic reaction rate in patients who remain on maintenance VIT. The 22% reaction rate is a minimal estimate caused by loss of venom sensitivity in some patients and residual venom-specific IgG antibody levels in others. Reevaluation of venom skin tests and IgG levels was possible in 43 patients. A tenfold decline from before VIT skin test results was observed in 27 patients (63%). Skin tests remained clearly positive in 32/43 (74%), became weakly positive in 9/43 (21%), and 2/43 (5%) became negative. The IgG level declined from typical maintenance levels before stopping VIT (mean 7.2 +/- 1.2 micrograms/ml) to levels typical of untreated patients at the time of retesting (mean 1.95 +/- 0.3 micrograms/ml). Despite the marked fall of IgG antibody, one third of the patients still had levels in the average range observed in patients receiving maintenance VIT. We conclude that there is a substantial risk of anaphylactic sting reaction if VIT is stopped while venom sensitivity persists.     

脑出血患者血浆高迁移率族蛋白B1浓度的检测及临床意义

目的:揭示脑出血患者血浆高迁移率族蛋白B1浓度的变化,探讨其对预后的预测价值。方法:收集高血压性基底节区出血患者作为脑出血组,共98例。收集同期健康体检人群作为对照组,共40例。脑出血组静脉血在入院时获得。对照组静脉血体检时获得。ELISA检测血浆高迁移率族蛋白B1浓度。统计分析其与患者预后的相关性。结果:脑出血后1个月内死亡29例(29.6%)。t检验显示,脑出血组血浆高迁移率族蛋白B1浓度(7.6±2.7)ng/ml显著高于对照组(1.3±0.4)ng/ml(P<0.001)。多因素分析显示,血浆高迁移率族蛋白B1浓度与脑出血患者入院时GCS评分呈显著负相关(P<0.001),是脑出血1个月内死亡的独立危险因素(OR=1.384,95%CI=1.114～1.551,P<0.01)。ROC曲线分析显示,血浆高迁移率族蛋白B1浓度预测脑出血1个月内死亡有显著预测价值(曲线下面积=0.823,95%CI=0.759～0.892,P<0.001),且判定血浆高迁移率族蛋白B1浓度7.9ng/ml,对预测脑出血1个月内死亡有86.2%的灵敏度和79.7%的特异度。结论:脑出血后血浆高迁移率族蛋白B1浓度升高,临床检测这个指标有助于早期判断脑出血患者的预后。     

Poor antibody response after tetanus and pneumococcal vaccination in immunocompromised, HIV-infected patients.

Ten patients with symptomatic HIV infection (six with ARC, four with AIDS) received tetanus and 23-valent pneumococcal vaccination. Anti-tetanus IgG and IgM, and anti-pneumococcal IgG against all 23 capsular types of the vaccine were measured on days 0, 11, 17, 30, and 90. Anti-pneumococcal IgG were simultaneously determined in two plasma pools of 100 healthy unimmunized blood donors and of 112 healthy adults who had previously received a 14-valent pneumococcal vaccination. Peak IgG responses to both vaccines were observed on day 17; thereafter, the antibody levels gradually fell again. Anti-tetanus IgG rose from 0.6 U/ml (geometric mean) to 2.0 U/ml on day 17. Anti-tetanus IgM remained unchanged. Anti-pneumococcal IgG increased only by 1.14-fold compared with pre-vaccination levels (geometric mean of IgG rises against all 23 polysaccharides in 10 patients), and exceeded the upper 95% limit of unvaccinated blood donors in only 30 out of 230 specimens. Pre-vaccination levels for pneumococcal type-specific IgG were significantly higher in HIV-infected patients compared with the pool of unimmunized healthy controls, possibly indicating a higher rate of previous pneumococcal infections in HIV-seropositive subjects. However, post-pneumococcal vaccination levels were significantly lower in HIV-infected patients than in the pool of healthy controls. The increase in anti-tetanus IgG significantly correlated with the level of CD4 lymphocytes and with in vitro lymphocyte proliferation by pokeweed mitogen (5 micrograms/ml) and phytohaemagglutinin (2.5 micrograms/ml), confirming a particularly low vaccination response in patients who were severely immunocompromised.     

Neuroendocrine-immune interactions associated with loss and restoration of immune system function in spinal cord injury and stroke patients

Both natural and adaptive immune responses were shown to be strikingly decreased in initial blood samples from 34 spinal cord injury and stroke patients. NK-cell function decreased to 24.8% (mean) 2 weeks after spinal cord injury in previously healthy young adults whose control group revealed a mean NK-cell function of 48.7%. This was accompanied at 2 weeks by increased plasma ACTH (mean of 17.0 pg/ml from 17 patients compared to a mean of 11.2 pg/ml from 12 controls) and urine free cortisol levels (mean of 152.1 micrograms/24 h from 9 patients compared to 53.6 micrograms/24 h from 15 controls). T-cell function and/or activation decreased to below normal values within 3 months after injury as revealed by lymphocyte transformation that was 32.8% of normal at 3 months. T-cell activation diminished as shown by a mean IL-2 receptor level of 179.3 units/ml in patients compared to 328.2 units/ml in controls. Serial monitoring of NK- and T-cell function revealed that specific physical rehabilitation therapy over a period of 6 months after injury restored NK- and T-cell function to near normal levels in most patients. This improvement was accompanied by a parallel rise in the patient's functional independence measurement scores. Results suggest critical neuroendocrine-immune system interactions in the restoration of immune function. Cortisol levels reverted to normal after 6 months of rehabilitation. Limited data suggest that natural immune system depression, NK-cell function, persists in spinal cord injury patients not receiving rehabilitation therapy (mean NK-cell lysis of 10.3%; p < 0.01).     

病毒性肝炎患者血清脂多糖结合蛋白检测及其意义

目的观察慢性肝炎、重型肝炎患者血清脂多糖结合蛋白(Lipopolysaccharidebindingprotein,LBP)的变化.方法用酶联免疫吸附法检测16例慢性肝炎患者,15例肝炎肝硬化患者,12例重型肝炎和17例健康对照者血清中LBP水平.结果慢性肝炎组患者血清LBP含量35166.25μg/L,显著高于健康对照组18590.00μg/L,而慢性肝炎组与重型肝炎组比较,慢性肝炎>肝炎肝硬化>重型肝炎,各组间差异显著,血清LBP含量与血浆PTA水平呈正相关(r=0.3958,P<0.01),而与血清ALTTBiL水平无明显相关性(r分别为0.1645和0.1894,P值均>0.05).结论血清LBP可能作为了解肝脏代偿能力指标之一.     

脑外伤患者血浆HMGB1的检测及临床意义

目的:揭示脑外伤患者血浆高迁移率族蛋白B1(HMGB1)浓度的变化,探讨其在脑损伤中的作用及对预后的预测价值.方法:收集重型脑外伤患者作为脑外伤组,共112例.收集同期健康体检人群作为正常对照组,共40例.对照组静脉血体检时获得.脑外伤组静脉血在入院时获得.ELISA测定血浆HMGB1浓度.结果:脑外伤后1个月内死亡3...     

Lipid peroxide, beta-carotene and alpha-tocopherol in ischaemic stroke and effect of exogenous vitamin E supplementation on outcome

30 patients with CT proven infarct presenting within 24 hours of the acute event were included in the study with 20 age and sex matched controls. On day 1 and day 15 of stroke, levels of plasma lipid peroxide (oxidant) and plasma alpha-tocopherol and beta carotene (antioxidant) were estimated. The patients were randomly assigned to two groups, one group receiving 300 mg/day of vitamin E for 15 days. Neurological examination was conducted according to Mathew scale on day 1 and day 15 and rehabilitation assessment was done at day 15 and at 6 weeks according to Barthel Index. On day 1, the mean value of plasma lipid peroxidation in controls was 4.97 +/- 1.44 nmol/ml and in stroke patients 5.89 +/- 1.56 nmol/ml (p < 0.05). The plasma beta-carotene in controls was 2.35 +/- 1.09 mg/L while in stroke patients was 1.07 +/- 0.55 mg/L (p < 0.001) and plasma alpha-tocopherol in control 9.74 +/- 2.76 micrograms/ml as compared to 7.57 +/- 2.92 micrograms/ml in stroke patients (p < 0.02). Initially the plasma lipid peroxide levels are high and antioxidant levels are low in patients of ischemic stroke. Exogenous vitamin E supplementation does not have any significant effect on early neurological outcome but it does bring about significant changes in subsequent recovery and rehabilitation of patients of stroke.     

急性阑尾炎患者血浆β-防御素-2的检测及临床意义

目的:探索急性阑尾炎患者血浆β-防御素-2浓度的变化,探讨其与急性阑尾炎患病危险性的相关性。方法:收集急性阑尾炎患者作为阑尾炎组,共208例。收集同期健康体检者作为对照组,共104例。ELISA检测血浆β-防御素-2浓度。统计分析其与急性阑尾炎患病危险性的相关性。结果:t检验显示,阑尾炎组血浆β-防御素-2浓度(398.6±128.0)pg/ml显著低于对照组(629.1±47.2)pg/ml(t=6.470,P<0.05)。Logistic回归分析显示,血浆β-防御素-2浓度(OR=0.429,95%CI=0.251～0.795,P<0.05)是罹患急性阑尾炎的独立危险因素。ROC曲线分析显示,血浆β-防御素-2浓度预测罹患急性阑尾炎有显著预测价值(曲线下面积=0.817,95%CI=0.778～0.865,P<0.001),且判定血浆β-防御素-2浓度<612.4 pg/ml,对预测罹患急性阑尾炎有75.0%的灵敏度和72.1%特异度。结论:急性阑尾炎患者血浆β-防御素-2水平降低,血浆β-防御素-2水平降低可能是急性阑尾炎发病的危险因素。     

慢性牙周炎患者血浆β-防御素-3的检测及其临床意义

目的:揭示慢性牙周炎患者血浆β-防御素-3浓度的变化,探讨其与慢性牙周炎患病危险性的相关性.方法:收集慢性牙周炎患者作为牙周炎组,共78例.收集同期牙周健康者作为对照组,共40例.ELISA检测血浆β-防御素-3浓度.统计分析其与慢性牙周炎患病危险性的相关性.结果:协方差分析显示,牙周炎组血浆β-防御素-3浓度(87....     

Elevated levels of lipopolysaccharide-binding protein and soluble CD14 in plasma in neonatal early-onset sepsis

No data on lipopolysaccharide-binding protein (LBP) in newborns with sepsis have been available up to now. We therefore determined levels of LBP and soluble CD14 (sCD14) in plasma of healthy and septic neonates in order to evaluate their potential diagnostic role. The study included prospectively collected patient samples of two recently published studies on cytokine expression in neonatal sepsis. Twenty-nine septic patients were enrolled in the present analysis. Samples--either cord blood or peripheral blood--from patients admitted within the first 24 h of life for suspicion of sepsis and cord blood samples of a control group of 40 healthy mature infants delivered spontaneously were analyzed. For seven patients of the septic group, a second sample collected between 24 and 48 h of life was available. Levels of sCD14 and LBP in plasma were determined by an enzyme immunoassay using recombinant CD14 and LBP as standards. LBP and sCD14 were correlated to cytokine plasma levels. In septic neonates, LBP (median, 36.6 versus 7.8 microg/ml; P < 0.001) and sCD14 (median, 0.42 versus 0.28 microg/ml; P < 0.001) levels were highly elevated when compared to those of healthy neonates and strongly correlated to granulocyte colony-stimulating factor (G-CSF), interleukin-1beta (IL-1beta), IL-6, and IL-8 levels. LBP levels in septic neonates analyzed between 24 and 48 h of life even increased when compared to samples obtained at or shortly after delivery (median, 36.6 versus 60 microg/ml; P = 0.038). In summary, levels of LBP in plasma of neonates with early-onset sepsis are significantly elevated; the elevated plasma levels seem to persist for more than 24 h, which could provide the clinician with a prolonged time period to identify the newborn with bacterial sepsis.     

血浆TNF-α浓度对慢性荨麻疹的诊断价值

目的：揭示慢性荨麻疹患者血浆肿瘤坏死因子-α（TNF-α）浓度的变化,分析其对慢性荨麻疹的诊断价值。方法：选取门诊治疗的慢性荨麻疹患者及健康体检者各86例,ELISA检测血浆TNF-α浓度,对数据进行统计分析。结果：慢性荨麻疹患者血浆TNF-α浓度（4.2±1.8）ng/ml显著高于对照组（1.8±0.7）ng/ml（P〈0.001）,与临床评价总积分（r=0.471,P〈0.01）和病程（r=0.424,P〈0.01）呈显著正相关。多因素分析显示,血浆TNF-α浓度（OR=1.738,95%CI=1.117～4.924,P〈0.05）是慢性荨麻疹发病的独立危险因素。ROC曲线辨别了血浆TNF-α浓度的曲线下面积（曲线下面积=0.842,95%CI=0.775～0.913,P〈0.001）和判定界值（〉2.8 ng/ml）,对诊断慢性荨麻疹有较高的灵敏度（83.7%）和特异度（79.1%）。结论：TNF-α可能参与慢性荨麻疹的发病机制,其浓度可有效诊断慢性荨麻疹。     

血浆YKL-40浓度对危重症患者并发腹腔间隙综合征的预测作用

目的:揭示危重症患者血浆YKL-40浓度的变化,探讨其对危重症患者并发腹腔间隙综合征的预测价值。方法:收集危重症患者和健康体检人群各98例。健康体检人群静脉血体检时获得,危重症患者静脉血在入院时获得。ELISA检测血浆YKL-40浓度。结果:危重症患者血浆YKL-40浓度(146.8±79.5)ng/ml显著高于健康体检者(39.4±12.5)ng/ml(t=8.749,P<0.01),与APACHEⅡ评分,呈显著正相关性(r=0.591,P<0.01)。28例(28.6%)并发腹腔间隙综合征。多因素分析显示,血浆YKL-40浓度(OR=1.492,95%CI=1.231～2.116,P<0.01)是危重症患者并发腹腔间隙综合征的独立危险因素。ROC曲线分析显示,血浆YKL-40浓度预测危重症患者并发腹腔间隙综合征有显著预测价值(曲线下面积=0.842,95%CI=0.791～0.914,P<0.001),且判定血浆YKL-40浓度>172.4 ng/ml,对预测并发腹腔间隙综合征有82.1%的灵敏度和78.6%的特异度。结论:危重症患者并发腹腔间隙综合征后,血浆YKL-40浓度显著升高,临床检测YKL-40作为有预报价值的标志物,有助于早期判断腹腔间隙综合征的发生。     

Clinical study on the serum carcinoembryonic antigen, immunosuppressive acidic protein and C-reactive protein levels in patients with adult T cell leukemia

Serum carcinoembryonic antigen (CEA), immunosuppressive acidic protein (IAP) and C-reactive protein (CRP) levels were measured in patients with adult T cell leukemia (ATL) in order to clarify their significance in this disease. Mean (+/- SD) serum CEA levels in 11 patients with acute ATL (3.1 +/- 1.3 ng/ml) and 7 patients with smoldering ATL (3.1 +/- 0.5 ng/ml) were significantly higher than in sera of 222 healthy controls (2.4 +/- 1.3 ng/ml). However, the levels in 7 patients with chronic ATL and healthy controls showed no differences. On the other hand, mean (+/- SD) serum IAP levels in patients with acute ATL (928 +/- 395 micrograms/ml), chronic ATL (487 +/- 125 micrograms/ml) and smoldering ATL (429 +/- 90 micrograms/ml) were significantly higher than in sera of healthy controls (359 +/- 103 micrograms/ml). However, the levels in patients with smoldering ATL and healthy controls showed no differences. Serum IAP levels in crisis in chronic and smoldering ATL were similar to those in patients with acute ATL. 85% of ATL patients with IAP levels above 500 micrograms/ml had CRP levels above 1+. Serum CEA, IAP and CRP levels were serially measured in a number of patients. Serum IAP and CRP levels reflected each patient's clinical course more than serum CEA levels. Overall the simultaneous measurements of serum CEA, IAP and CRP levels revealed a potential usefulness for determination of ATL subtype, and serum IAP and CRP levels may provide a way to evaluate the effectiveness of chemotherapy.     

Kinetic fluorescence RT-PCR is highly sensitive for detection of germ-cell-tumor-specific transcripts in peripheral blood

The aim of our study was to determine whether conventional staging in patients with testicular germ-cell-tumors (GCT) could be supplemented by quantification of beta-human choriogonadotropin mRNA levels in peripheral blood using kinetic fluorescence RT-PCR. Blood samples from 41 patients with GCT of different clinical stages (CS) were pre-therapeutically examined by kinetic fluorescence RT-PCR with the LightCycler for beta-human chorionic gonadotropin (beta-HCG) mRNA expression levels. The controls comprised of samples taken from patients 3 months after treatment, from patients with inflammatory testicular diseases or non-germ-cell-tumors and from healthy males (n=66). Six positive results [cut-off level: normalized beta-HCG mRNA (Nbeta-HCG) >400 relative gene expression (RGE)] were found in controls (specificity 90.9%, 95% CI: 76.9-97.3%). The overall ratio of positive PCR results in the group of GCT patients was 82.92% (34/41) (CS I 18/23, CS IIa-b 6/7, CS >IIb 10/11) (sensitivity 82.9%, 95% CI: 65.1-91.2%). The average Nbeta-HCG level in patients with clinical stage I tumors was 63772.0+/-125720.5 (mean +/- standard deviation) relative gene expression (RGE), 35076.0+/-52253.5 RGE in those with CS IIa-b tumors and 87298.3+/-120895.3 RGE in those with CS >IIb tumors. Kinetic fluorescence RT-PCR for tumor-specific gene products is, in contrast to qualitative RT-PCR, a promising approach to improve conventional staging in clinical low-stage testicular germ-cell-tumors. With high specificity, its sensitivity is higher than that of the corresponding serum tumor marker (82.92% vs 48.72%).     

Safety, immunogenicity, and efficacy of a Plasmodium falciparum vaccine comprising a circumsporozoite protein repeat region peptide conjugated to Pseudomonas aeruginosa toxin A.

Twenty-one malaria-naive volunteers were immunized with a vaccine consisting of a 22-kDa recombinant peptide (R32LR), derived from the repeat region of Plasmodium falciparum circumsporozoite (CS) protein, covalently coupled to detoxified Pseudomonas aeruginosa toxin A. Nineteen volunteers received a second dose of vaccine at 8 weeks, and eighteen received a third dose at 8 to 12 months. The vaccine was well tolerated, with only one volunteer developing local discomfort and induration at the site of injection which limited function for 48 h. The geometric mean anti-CS immunoglobulin G antibody concentration 2 weeks after the second dose of vaccine was 10.6 micrograms/ml (standard deviation = 3.0 micrograms/ml). Eleven volunteers (52%) developed anti-CS antibody levels of greater than 9.8 micrograms/ml, the level measured in the one volunteer protected against P. falciparum challenge after immunization with the alum-adjuvanted recombinant protein R32tet32 in a prior study. Three separate experimental challenges were conducted with 10 volunteers 2 to 4 weeks after the third dose of vaccine. The four best responders, on the basis of antibody levels (6 to 26 micrograms/ml), were challenged with two infected-mosquito bites, but only one of four immunized volunteers and one of three malaria-naive controls became parasitemic. In a second challenge study using five infected-mosquito bites as the challenge dose, three of three malaria-naive control volunteers and two of three immunized volunteers developed malaria. The third vaccine was apparently completely protected. In the third and last challenge, three of three controls and five of five vaccinees became infected. Sera obtained on the days of challenge inhibited sporozoite invasion of hepatocytes variably in vitro (range, 45 to 90% inhibition), but the degree of inhibition did not correlate with protection. Although antibody against the CS repeat region may protect some individuals against experimental challenge, this protection cannot be predicted from antibody levels by current in vitro assays. The functionality and fine specificity of anti-CS antibody are probably critical determinants.