Authors’ Reply: Advanced Tertiary Lymphoid Tissues in Protocol Biopsies in Kidney Transplant Recipients: Addressing Additional Methods To Detect Intragraft B Cells

In our manuscript¹ “Advanced tertiary lymphoid tissues in protocol biopsies are associated with progressive graft dysfunction on kidney transplant recipients,” we demonstrated that developmentally mature advanced tertiary lymphoid tissues (stage II TLTs), ectopic lymphoid tissues formed in chronic inflammatory organs, in protocol biopsies can be a histologic marker for progressive graft dysfunction in kidney transplant recipients. We also showed pretransplantation rituximab treatment dramatically attenuated the development of stage II TLTs in subgroup analysis.

We appreciate Romy et al.’s insightful comments and interest in our study. They raise two important issues for consideration.² The first relates to the statement “TLTs in these patients harbored far fewer B cells than TLTs in aged kidneys and the kidney with chronic kidney disease” in the Results section. We previously showed that patients aged >60 years old exhibit TLTs in the kidney, and aged patients with CKD exhibit a higher proportion of stage II TLTs than those without CKD.^3,4 The second concern of Romy et al. relates to the underestimation of B cell numbers using CD20 antibodies in patients who received rituximab before transplantation. To investigate this possibility, we performed CD79a staining for transplant kidneys with or without rituximab treatment, and confirm CD79a⁺ B cells are almost undetectable in T cell–dominated TLTs (Figure 1). Additionally, in this manuscript, we defined TLTs as organized lymphocyte aggregates with signs of proliferation and defined the aggregates as >60 lymphocytes (T or B cells). The B cell number itself in the aggregate therefore does not affect the definition of TLTs in this study. We therefore think the potential underestimation of B cell numbers only using CD20 as a marker for B cells in our study of patients who have undergone a transplant and are receiving rituximab treatment did not have major effects on the main results and conclusions of our manuscript. This notion is also supported by the rate of stage I TLT development in patients with or without rituximab treatment being comparable.

Figure 1.

Tertiary lymphoid tissues in transplanted kidneys with or without rituximab treatment. Stained by anti-CD79a antibody (Agilend DAKO, M7050) and anti-CD3ε antibody (Abcam, ab5690). The section of the kidney with rituximab treatment is the serial section of Supplemental Figure 2D in our manuscript. Dashed lines indicate the localization of the renal capsule. Scale bars: 100 μm.

In conclusion, we think our study documents that advanced stage II TLTs are associated with progressive graft dysfunction, independent of interstitial inflammation.

Disclosures

M. Yanagita reports receiving research funding from Boehringer Ingelheim and Tanabe Mitsubishi; reports receiving honoraria from Astellas, Chugai, Kyowa Kirin, and others for lectures; and reports having other interests/relationships with the International Society of Nephrology and the Japanese Society of Nephrology. J. Floege reports having consultancy agreements with AstraZeneca, Bayer, Calliditas, Idorsia, Novartis, Omeros, and Travere; and reports receiving honoraria from AstraZeneca, Bayer, Calliditas, Fresenius, Idorsia, Novartis, Omeros, Travere, and Vifor. All remaining authors have nothing to disclose.

Funding

None.