Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota, USA.
Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota, USA.
Kidney Int. 2021 Jul;100(1):155-170. doi: 10.1016/j.kint.2021.02.038. Epub 2021 Mar 25.
Heavy chain/light chain (HLC) antibodies target conformational epitopes at the junctions of the heavy chain and light chain constant regions (CH1 and CL) of serum IgGκ, IgGλ, IgAκ, IgAλ, IgMκ, and IgMλ to provide quantitation of intact HLC pairs. Here, we developed an HLC tissue immunofluorescence protocol to test if it can complement conventional immunofluorescence in the diagnosis of monoclonal gammopathy-associated kidney diseases. HLC immunofluorescence was performed on archived frozen tissue of 104 kidney biopsies. The sensitivity and specificity of HLC immunofluorescence was confirmed by testing cases of lupus nephritis, other polyclonal immunoglobulin nephropathies, and light chain nephropathies (light chain amyloidosis and deposition disease). Testing of ten cases of the IgG variant of proliferative glomerulonephritis with monoclonal immunoglobulin deposits excluded monoclonal deposits in two by revealing positivity for IgGκ and IgGλ. Testing of 12 cases of monotypic IgA nephropathy excluded monoclonal deposits in six by revealing staining for IgAκ and IgAλ. Testing of six cases of monotypic fibrillary glomerulonephritis excluded monoclonal deposits in three by revealing positivity for IgGκ and IgGλ. None of 14 cases of glomerulonephritis in which HLC immunofluorescence unmasked polytypic deposits were associated with a serum or urine monoclonal immunoglobulins matching the conventional immunofluorescence results. HLC immunofluorescence outperformed paraffin immunofluorescence and IgG subclass staining in 10/13 (77%) of cases. Testing of 18 cases of cryoglobulinemic glomerulonephritis showed better correlation with serum cryoprecipitate immunofixation than conventional immunofluorescence with regards to the type of cryoglobulin in 47% of cases. Thus, HLC immunofluorescence is a valuable ancillary technique in kidney pathology for the diagnosis of monoclonal gammopathy-associated nephropathies, and could be utilized to confirm or exclude the monoclonal nature of deposits.
重链/轻链（HLC）抗体针对血清 IgGκ、IgGλ、IgAκ、IgAλ、IgMκ 和 IgMλ 的重链和轻链恒定区（CH1 和 CL）连接处的构象表位，提供完整 HLC 对的定量。在这里，我们开发了一种 HLC 组织免疫荧光方案，以测试其是否可以补充单克隆丙种球蛋白病相关肾脏疾病的常规免疫荧光。对 104 例肾脏活检的存档冷冻组织进行了 HLC 免疫荧光检测。通过检测狼疮性肾炎、其他多克隆免疫球蛋白肾病和轻链肾病（轻链淀粉样变性和沉积病）的病例，验证了 HLC 免疫荧光的敏感性和特异性。对 10 例 IgG 变体增生性肾小球肾炎的检测排除了其中 2 例的单克隆免疫球蛋白沉积，因为 IgGκ 和 IgGλ 呈阳性。对 12 例单克隆 IgA 肾病的检测排除了其中 6 例的单克隆沉积，因为 IgAκ 和 IgAλ 染色呈阳性。对 6 例单克隆纤维状肾小球肾炎的检测排除了其中 3 例的单克隆沉积，因为 IgGκ 和 IgGλ 呈阳性。在 14 例通过 HLC 免疫荧光揭示多克隆沉积的肾小球肾炎病例中，均未发现与常规免疫荧光结果相符的血清或尿液单克隆免疫球蛋白。在 13 例（77%）病例中，HLC 免疫荧光的表现优于石蜡免疫荧光和 IgG 亚类染色。在 18 例冷球蛋白血症性肾小球肾炎的检测中，HLC 免疫荧光与血清冷沉淀免疫固定电泳的相关性优于常规免疫荧光，47%的病例中冷球蛋白的类型得到了更好的确认。因此，HLC 免疫荧光是肾脏病理学中单克隆丙种球蛋白病相关肾病的一种有价值的辅助技术，可以用于确认或排除沉积物的单克隆性质。
