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Abstract Background Multiple myeloma (MM) often causes renal tubular damage, such as the light chain cast nephropathy (LCCN) and the light chain proximal tubulopathy (LCPT). The excessive light chains deposited in the proximal and distal tubules usually manifest with different characteristics, leading to a rare coexistence of the two pathological conditions. Here we report a unique case of a patient with multiple myeloma (MM) who presented with acute kidney injury (AKI) due to dual conditions of λ light chain-restricted non-crystalline LCPT and LCCN. This report reviews the clinical presentation and histological findings, comparing them with previously published cases. Case presentation A 49-year-old male patient was admitted with a chief complaint of “fatigue, loss of appetite for 40 days and elevated blood creatinine for 10 days.” In serum and urine, the λ light chain level and the ratio of κ to λ free light chain were 1235 mg/dl and 93.25 mg/dl, 0.0022 and 0.0316, respectively. Additionally, serum protein electrophoresis showed an M-spike with monoclonal IgD-λ. Bone marrow puncture revealed 30.5% primitive naive plasma cells, indicative of IgD-λ MM. Light microscopy of kidney biopsy specimen showed periodic acid-Schiff (PAS)-negative cytoplasm in some proximal tubules and PAS-negative casts with a rigid appearance in some distal tubule lumens. On immunofluorescence, these proximal tubular epithelial cells cytoplasm and casts stained exclusively with λ-light chains. Electron microscopy did not reveal any crystalline inclusions. Given the clinical and bone marrow puncture findings, the overall pathological presentation was LCPT with LCCN secondary to IgD-λ MM. After chemotherapy and dialysis, the patient’s condition was improved and he was tracked in follow-ups. Conclusion In some tubular renal injuries caused by MM, the morphological changes are subtle and often overlooked. In this paper, we present a rare case of LCPT with LCCN showing λ restriction in patient with MM. Through the clinicopathological analysis of patients, the understanding of the disease can be deepened and the diagnosis rate improved.

Hantaan virus (HTNV), the causative pathogen of hemorrhagic fever with renal syndrome (HFRS), is a negative RNA virus belonging to the Orthohantaviridae family. HTNV envelope glycoprotein (GP), encoded by the genomic medium segment, is immunogenic and is therefore a promising vaccine candidate. Major histocompatibility complex class I (MHC-I) epitopes derived from HTNV has been extensively studied, but little is known of MHC-II epitopes. In silico predictions based on four databases indicated that the full-length HTNV GP has 1121 15-mer epitopes, of which 289 had a high score for binding to the human and murine MHC-II superfamily. It found that epitope ILTVLKFIANIFHTS could potentially bind most MHC-II molecules covering human and murine haplotypes. Dominant epitopes were validated by enzyme-linked immunospot assay of splenocytes from immunized mice; 6 of 10 epitopes supported the predictions including TATYSIVGPANAKVP, TKTLVIGQCIYTITS, FSLLPGVAHSIAVEL, CETYKELKAHGVSCP, CGLYLDRLKPVGSAY, and NLGENPCKIGLQTSS. Conservation analysis of dominant epitopes revealed host–virus interactions without geographic stratification, thus meeting the requirements of candidate vaccines for large-population prophylaxis. These findings provide insight into hantavirus antigenicity and suggest that vaccines targeting MHC-II could provide immune protection in large population to complement symptomatic therapies for the treatment of HFRS.