Abstract：
BACKGROUND: Human T-cell leukemia virus type 1 (HTLV-1) is a blood-borne virus, and mandatory testing of donated blood for HTLV-1 antibodies has been adopted by Japanese Red Cross blood centers since 1986. A confirmatory line immunoassay was initiated in 2019 for individuals who were seroreactive in the screening test. This decreased the incidence of indeterminate individuals, however, donors with indeterminate results are not informed of their HTLV-1 seroreactivity and they can continue to donate blood.
OBJECTIVE: To clarify the characteristics of indeterminate line immunoassay results among Japanese blood donors.
METHODS: Of 759,259 blood donors in the Kyushu district of Japan, an area endemic for HTLV-1, 101 cases were classified as indeterminate by line immunoassay testing. We examined these cases using alternative secondary antibodies, anti-human-Ig (IgG/IgM/IgA) and -IgM antibodies, to detect the early phase of HTLV infection.
RESULTS: Using anti-human-Ig and -IgM antibodies, HTLV infection status was confirmed in 37 individuals (HTLV-1-positive, 2; HTLV-positive, 27; HTLV-negative, 8). Among the remaining 64 indeterminate individuals, we identified one HTLV-2-infected 18-year-old female. A previous blood donation from this individual showed a negative anti-HTLV screening test result (signal-to-cutoff ratio = 0.1). Therefore, this case was considered to be an HTLV-2 seroconversion case.
CONCLUSIONS: These results indicate that the procedure for diagnosing HTLV infection should be reconsidered and that an accurate detection system for the early phase of HTLV infection is urgently needed for public health in Japan. Moreover, the issue of HTLV-2 infection needs a higher profile in Japan.
OBJECTIVE: To clarify the characteristics of indeterminate line immunoassay results among Japanese blood donors.
METHODS: Of 759,259 blood donors in the Kyushu district of Japan, an area endemic for HTLV-1, 101 cases were classified as indeterminate by line immunoassay testing. We examined these cases using alternative secondary antibodies, anti-human-Ig (IgG/IgM/IgA) and -IgM antibodies, to detect the early phase of HTLV infection.
RESULTS: Using anti-human-Ig and -IgM antibodies, HTLV infection status was confirmed in 37 individuals (HTLV-1-positive, 2; HTLV-positive, 27; HTLV-negative, 8). Among the remaining 64 indeterminate individuals, we identified one HTLV-2-infected 18-year-old female. A previous blood donation from this individual showed a negative anti-HTLV screening test result (signal-to-cutoff ratio = 0.1). Therefore, this case was considered to be an HTLV-2 seroconversion case.
CONCLUSIONS: These results indicate that the procedure for diagnosing HTLV infection should be reconsidered and that an accurate detection system for the early phase of HTLV infection is urgently needed for public health in Japan. Moreover, the issue of HTLV-2 infection needs a higher profile in Japan.
摘要：
背景：人类T细胞白血病病毒1型（HTLV-1）是一种血液传播的病毒，自1986年以来，日本红十字会血液中心已采用强制性检测捐赠血液中的HTLV-1抗体。2019年开始对在筛选测试中具有血清反应性的个体进行验证性免疫分析。这减少了不确定个体的发生率，然而,结果不确定的献血者不会被告知他们的HTLV-1血清反应性,他们可以继续献血.
目的：阐明日本献血者中不确定行免疫测定结果的特征。
方法：在日本九州地区的759,259名献血者中，HTLV-1的流行区域，101例通过行免疫测定测试被分类为不确定的。我们使用替代二级抗体检查了这些病例，抗人-Ig（IgG/IgM/IgA）和-IgM抗体，检测HTLV感染的早期阶段。
结果：使用抗人-Ig和-IgM抗体，在37人中确认了HTLV感染状态（HTLV-1阳性，2；HTLV阳性，27；HTLV阴性，8).在剩下的64个不确定的个体中，我们确定了一名HTLV-2感染的18岁女性。来自该个体的先前献血显示阴性抗HTLV筛查测试结果(信号截止比=0.1)。因此,该病例被认为是HTLV-2血清转换病例.
结论：这些结果表明，应重新考虑诊断HTLV感染的程序，并且日本的公共卫生迫切需要针对HTLV感染早期的准确检测系统。此外，HTLV-2感染的问题在日本需要得到更高的重视.
目的：阐明日本献血者中不确定行免疫测定结果的特征。
方法：在日本九州地区的759,259名献血者中，HTLV-1的流行区域，101例通过行免疫测定测试被分类为不确定的。我们使用替代二级抗体检查了这些病例，抗人-Ig（IgG/IgM/IgA）和-IgM抗体，检测HTLV感染的早期阶段。
结果：使用抗人-Ig和-IgM抗体，在37人中确认了HTLV感染状态（HTLV-1阳性，2；HTLV阳性，27；HTLV阴性，8).在剩下的64个不确定的个体中，我们确定了一名HTLV-2感染的18岁女性。来自该个体的先前献血显示阴性抗HTLV筛查测试结果(信号截止比=0.1)。因此,该病例被认为是HTLV-2血清转换病例.
结论：这些结果表明，应重新考虑诊断HTLV感染的程序，并且日本的公共卫生迫切需要针对HTLV感染早期的准确检测系统。此外，HTLV-2感染的问题在日本需要得到更高的重视.
