The expression of surface antigen Leu 1 by ocular adnexal lymphoid neoplasms.

Leu 1 is a surface membrane antigen expressed by benign systemic T cells, most cases of B-cell-derived chronic lymphocytic leukemia, and approximately one half of the systemic B-cell lymphomas. Benign systemic B cells are Leu 1-. Our studies showed that the percentage of Leu 1+ cells was essentially the same as the percentage of OKT3+E+ (T) cells in six ocular adnexal pseudolymphomas, strongly suggesting that the benign B cells in these lesions were similarly Leu 1-. These studies also showed that malignant B cells in six of 15 (40%) ocular B-cell lymphomas were Leu 1+. Thus, the expression of Leu 1 by some malignant ocular adnexal B cells but not by benign ocular adnexal B cells appears to be analogous to the situation for lymph nodal and other systemic B cells. Although the explanation for the existence of this shared determinant is unknown, Leu 1 expression may possess clinical and diagnostic significance as a marker of neoplastic B cells.