T-cell co-regulatory molecule expression in renal angiomyolipoma and pulmonary lymphangioleiomyomatosis.

OBJECTIVES

To investigate the expression of B7-H3 and B7-H1 in renal angiomyolipoma (AML) tumors and the related, devastating syndrome of pulmonary lymphangioleiomyomatosis (LAM). We recently reported the high expression of T-cell co-regulatory B7-H ligands in renal cell carcinoma tumor vasculature and tumor cells. AML is a highly vascular tumor that most frequently emanates from the kidney. Events leading to its pathogenesis remain enigmatic and understudied.

METHODS

Immunohistochemical methods were used to assess the tumor expression of B7-H1 and B7-H3 in paraffin-embedded tissues from 110 patients who had undergone partial or radical nephrectomy for renal AML and from 7 patients with LAM who had undergone lung biopsy.

RESULTS

B7-H3 was expressed by 100% of the AML and LAM specimens, and B7-H1 expression was detected in only 2.7% of the specimens studied. Both membranous and cytoplasmic B7-H3 expression was noted in the smooth muscle, blood vessel, and lipoid cell components of the tumors; however, no expression was detected in the adjacent, normal parenchyma tissue. B7-H3 staining was noted in a median of 90% (range 20%-100%) of cells from renal AMLs and was independent of patient age (P = .43), sex (P = .27), tumor size (P = .21), and symptomatic presentation (P = .35).

CONCLUSIONS

B7-H3 was expressed at high levels in renal AMLs and pulmonary LAM, and B7-H1 was infrequently expressed in these tumors. Additional studies are needed to evaluate the utility of B7-H3 as a diagnostic marker or immune/angiogenic target to improve the management of AML and the potentially devastating condition of LAM, for which effective treatment is lacking.