Jung Seonkyung, Kim Myungshin, Lim Jihyang, Kim Yonggoo, Han Kyungja, Min Chang-Kee, Min Woo-Sung
Department of Laboratory Medicine, The Catholic University of Korea, Seoul, Korea.
Korean J Lab Med. 2008 Jun;28(3):169-73. doi: 10.3343/kjlm.2008.28.3.169.
Free light chain (FLC) is widely used to evaluate B-cell proliferative diseases. Herein, we estimated the clinical usefulness of serum FLC in multiple myeloma (MM).
Fifty-one patients were enrolled. We performed FLC analysis, protein electrophoresis (PEP), and immunofixation electrophoresis (IFE). FLC was measured using Toshiba 200 FR Neo with FREELITE, and kappa/lambda (kappa/lambda) ratio was calculated. We compared these parameters in 41 patients with increased FLC before and after bortezomib treatment. Complete response (CR) was defined as the disappearance of monoclonal (M) protein in serum and/or urine as measured by IFE. Partial response (PR) was defined as >or=50% reduction of serum M protein. Early objective response (EOR) included both CR and PR. Minimal response (MR) was defined as 25-49% reduction of M protein and stable disease (SD) as <25% reduction.
Forty-one (80.4%) of the 51 patients studied revealed increment of FLC and the five patients with no increment revealed an abnormal kappa/lambda ratio. Especially, all of the light chain myeloma and non-secretory myeloma showed increased FLC concentrations. Among the patients with EOR, 72.4% (21/29) showed a normal or subnormal FLC concentration after the first cycle of treatment. Otherwise, PEP and IFE normalized in 24.1% (7/29) and 24.1% (7/29), respectively. The ratio of decreased FLC after the first cycle of treatment was significantly different between EOR and other response groups (MR, SD) (90.6% vs 51.8%, P=0.011).
FLC was considered as a good diagnostic method in complement with PEP and IFE in MM, especially in light chain myeloma or non-secretory myeloma. Moreover, FLC is a useful monitoring tool because it reflects therapy results more rapidly owing to a short serum half-life.
游离轻链（FLC）被广泛用于评估B细胞增殖性疾病。在此，我们评估了血清FLC在多发性骨髓瘤（MM）中的临床应用价值。
纳入51例患者。我们进行了FLC分析、蛋白电泳（PEP）和免疫固定电泳（IFE）。使用东芝200 FR Neo和FREELITE检测FLC，并计算kappa/ lambda（κ/λ）比值。我们比较了41例FLC升高患者在硼替佐米治疗前后的这些参数。完全缓解（CR）定义为IFE检测血清和/或尿液中M蛋白消失。部分缓解（PR）定义为血清M蛋白降低≥50%。早期客观缓解（EOR）包括CR和PR。最小缓解（MR）定义为M蛋白降低25%-49%，疾病稳定（SD）定义为降低<25%。
51例研究患者中41例（80.4%）显示FLC升高，5例未升高患者显示κ/λ比值异常。特别是，所有轻链型骨髓瘤和非分泌型骨髓瘤患者的FLC浓度均升高。在EOR患者中，72.4%（21/29）在第一个治疗周期后FLC浓度正常或低于正常。否则，PEP和IFE分别在24.1%（7/29）和24.1%（7/29）患者中恢复正常。第一个治疗周期后FLC降低的比例在EOR组与其他缓解组（MR、SD）之间有显著差异（90.6%对51.8%，P=0.011）。
在MM中，FLC被认为是一种与PEP和IFE互补的良好诊断方法，尤其是在轻链型骨髓瘤或非分泌型骨髓瘤中。此外，FLC是一种有用的监测工具，因为其血清半衰期短，能更快地反映治疗结果。
