Gomez M J, Torosantucci A, Quinti I, Testa U, Peschle C, Cassone A
Laboratories of Bacteriology and Medical Mycology, Istituto Superiore di Sanità, Rome, Italy.
Cell Immunol. 1993 Dec;152(2):530-43. doi: 10.1006/cimm.1993.1310.
A mannoprotein fraction (MP-F2: mannan, > 90%; protein, 4.5%) from the human commensal microorganism Candida albicans was as efficient as interleukin-2 (IL-2) in generating cytotoxicity against the uninfected or human immunodeficiency virus type-1 (HIV-1) persistently infected monocytoid U937 cell line in cultured peripheral blood mononuclear cells (PBMC) from healthy human subjects. MP-F2-activated killing of U937 cells (U937-MAK) decreased progressively with advancing stages of HIV-1 infection to virtually no killing effect in PBMC from advanced AIDS subjects (AIDS PBMC). This decrease paralleled a lowered susceptibility of U937 cells to natural killer cell activity. In contrast, IL-2-activated killing of U937 cells (U937-LAK) was not affected by the progression of HIV infection and persisted at high levels in AIDS PBMC. To shed light on the mechanisms of U937-MAK and its decrease during HIV infection, IL-1 beta, IL-6, TNF-alpha, GM-CSF, and IFN-gamma production was analyzed. Decreases in TNF-alpha, GM-CSF, and IFN-gamma, but not IL-1 beta or IL-6, levels were observed in MP-F2-stimulated PBMC from HIV-infected subjects, compared to healthy controls. Interestingly, these cytokine levels fell before the onset of AIDS. The greatest relative drop was that of IFN-gamma, from 4600 (+/- 600) to 290 (+/- 160) and 217 (+/- 110) mean pg/ml (+/- SE) in PBMC from healthy donors (11 subjects), CDC stages II + III (14 subjects), and CDC stage IV (10 subjects), respectively. The following observations suggest that decreased IFN-gamma production plays a role in the abrogation of U937-MAK activity: (i) addition of neutralizing anti-IFN-gamma antibodies abolished both IFN-gamma and U937-MAK activity in PBMC from healthy subjects; (ii) substantial levels of IFN-gamma were detected in supernatants of PBMC cultures stimulated by IL-2, in line with preserved U937-LAK activity. Interestingly, anti-IFN-gamma antibodies also abolished TNF-alpha production, and the anti-TNF-alpha antiserum effect was comparable to that of anti-IFN-gamma in U937-MAK inhibition. In contrast, anti-TNF-alpha antibodies abrogated TNF-alpha activity, but only partially reduced IFN-gamma production. Thus, in human PBMC, U937-MAK activity progressively decreases with advancing stages of HIV infection, whereas U937-LAK activity is sustained. Furthermore, the present results indicate a pivotal role for IFN-gamma in U937 MAK activity, possibly through activation of TNF-alpha production.
从人体共生微生物白色念珠菌中提取的一种甘露糖蛋白组分（MP - F2：甘露聚糖含量>90%；蛋白质含量4.5%），在健康人类受试者的外周血单个核细胞（PBMC）培养物中，对于未感染或持续感染1型人类免疫缺陷病毒（HIV - 1）的单核细胞样U937细胞系产生细胞毒性的能力与白细胞介素 - 2（IL - 2）相当。随着HIV - 1感染阶段的推进，MP - F2激活的U937细胞杀伤作用（U937 - MAK）逐渐降低，在晚期艾滋病患者的PBMC（AIDS PBMC）中几乎没有杀伤效果。这种降低与U937细胞对自然杀伤细胞活性的敏感性降低平行。相比之下，IL - 2激活的U937细胞杀伤作用（U937 - LAK）不受HIV感染进程的影响，在AIDS PBMC中仍维持在较高水平。为了阐明U937 - MAK及其在HIV感染期间降低的机制，对IL - 1β、IL - 6、TNF - α、GM - CSF和IFN - γ的产生进行了分析。与健康对照相比，在HIV感染受试者的MP - F2刺激的PBMC中观察到TNF - α、GM - CSF和IFN - γ水平降低，但IL - 1β或IL - 6水平未降低。有趣的是，这些细胞因子水平在艾滋病发作之前就下降了。相对下降幅度最大的是IFN - γ，在健康供体（11名受试者）、疾病控制中心（CDC）II + III期（14名受试者）和CDC IV期（10名受试者）的PBMC中，分别从4600（±600）降至290（±160）和217（±110）平均pg/ml（±标准误）。以下观察结果表明，IFN - γ产生的减少在U937 - MAK活性的消除中起作用：（i）添加中和抗IFN - γ抗体消除了健康受试者PBMC中的IFN - γ和U937 - MAK活性；（ii）在IL - 2刺激的PBMC培养上清液中检测到大量的IFN - γ，这与U937 - LAK活性的保留一致。有趣的是，抗IFN - γ抗体也消除了TNF - α的产生，并且抗TNF - α抗血清在U937 - MAK抑制中的作用与抗IFN - γ相当。相比之下，抗TNF - α抗体消除了TNF - α活性，但仅部分降低了IFN - γ的产生。因此，在人类PBMC中，U937 - MAK活性随着HIV感染阶段的推进而逐渐降低，而U937 - LAK活性得以维持。此外，目前的结果表明IFN - γ在U937 MAK活性中起关键作用，可能是通过激活TNF - α的产生。
