Study on the mechanism of EBV reactivation and NK cell oncogenesis in hypersensitivity to mosquito bites

蚊虫叮咬超敏反应（HMB）的特征是强烈的局部皮肤症状，不仅包括红斑或大疱，还包括溃疡或瘢痕形成，以及全身症状，如高热、淋巴结病和肝脾肿大。最近的研究表明，EB病毒（EBV）DNA阳性的自然杀伤（NK）细胞，包括NK细胞白血病/淋巴瘤，HMB患者的淋巴细胞增殖。我们先前证实，HMB患者的CD 4 ^+T细胞在蚊子唾液腺提取物（SGE）的刺激下增殖良好，并在EB病毒从NK细胞中的潜伏状态重新激活中发挥关键作用。我们还发现，蚊虫叮咬可以通过蚊子抗原特异性CD 4 ^+T细胞诱导NK细胞中病毒癌基因LMP 1的表达，这与体内NK细胞的肿瘤发生有关。在这里，我们建立了HMB患者NK细胞的长期培养物。当这些培养的NK细胞与经蚊子SGE刺激的自体CD 4 ^+T细胞共培养时，LMP 1的表达和NK细胞的生长增强。结果表明，蚊子SGE刺激后，CD 4 ^+T细胞中IL-4、IL-10和TGF-β的mRNA和蛋白表达上调。在NK细胞和蚊SGE刺激的CD 4 ^+T细胞的共培养物中加入IL-2中和抗体可抑制LMP 1 mRNA的表达，而加入TGF-β中和抗体可增强LMP 1 mRNA的表达并抑制EBV的再活化。另一方面，IL-4和IL-10的中和抗体对LMP 1表达和NK细胞生长没有影响。此外，我们调查了一例氨苄青霉素引起皮疹的患者，发现氨苄青霉素可能在EBV感染的再激活中起关键作用，这意味着EBV再激活有助于该患者皮疹的发病机制。提示EBV的再活化不仅与HMB有关，还与其它变态反应性疾病有关。

Hypersensitivity to mosquito bites (HMB) is characterized by intense local skin symptoms, which consist of not only erythema or bulla but also ulceration or scarring, and systemic symptoms such as high fever, lymphadenopathy, and hepatosplenomegaly. Recent studies demonstrated the lymphoproliferation of EB virus (EBV) DNA-positive natural killer (NK) cells, including NK cell leukemia/lymphoma, in HMB patients. We previously demonstrated that CD4^+T cells of a patient with HMB proliferated well in response to mosquito salivary gland extracts (SGE) and played a key role in the reactivation of EBV from a latent state in NK cells. We also showed that mosquito bites can induce expression of the viral oncogene LMP1 in NK cells via mosquito antigen-specific CD4^+T cells, which is involved in the oncogenesis of NK cells in vivo. Here, we established long-term cultures of NK cells from the patients with HMB. When these cultured NK cells were cocultured with autologous CD4^+T cells stimulated by mosquito SGE, the expression of LMP1 and NK cell growth were enhanced. It was proved that mRNA and protein expressions of IL-4, IL-10, and TGF-β were upregulated in the CD4^+T cells by stimulation with the mosquito SGE. Adding a neutralizing antibody to IL-2 into the coculture of NK and mosquito SGE-stimulated CD4^+T inhibited the LMP1 mRNA expression, while adding a neutralizing antibody to TGF-β enhanced the LMP1 mRNA expression and suppressed the reactivation of EBV. On the other hand, neutralizing antibodies to IL-4 and IL-10 had no effects on LMP1 expression and NK cell growth. Furthermore, we investigated a patient with skin rash induced by ampicillin, and found that ampicillin might have played a key role in reactivation of EBV infection, implying that EBV reactivation contributed to the pathogenesis of skin rash in this patient. It suggests that the reactivation of EBV is related not only to HMB but also to other allergic diseases.