Discordance between surface and cytoplasmic expression of the Leu-4 (T3) antigen in thymocytes and in blast cells from childhood T lymphoblastic malignancies.
We have examined the expression of the Leu-4 (T3) antigen on the cell surface and in the cytoplasm of blast cells from 23 patients with T cell acute lymphoblastic leukemia and T cell lymphoblastic lymphoma. In the majority of cases (17), the Leu-4 antigen was absent from the cell surface; however, in 16 of these 17 cases, blast cells demonstrated cytoplasmic expression of Leu-4. This discordance between surface and cytoplasmic expression of Leu-4 was also found in thymocytes and appeared to be restricted to Leu-4, in that tests of other T cell antigens rarely revealed discordance between surface and cytoplasmic expression. To study further the cytoplasmic determinant identified by anti-Leu-4 in malignant T lymphoblasts, immunoprecipitation studies were performed that utilized biosynthetic labeling of established T cell lines derived from T lymphoblastic malignancies. By one-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis, identical Leu-4 polypeptide families were immunoprecipitated from surface Leu-4+ and surface Leu-4-/cytoplasmic Leu-4+ cell lines. Because T lymphoblastic malignancies represent proliferations of immature T cells, and because the cases studied demonstrated surface phenotypes corresponding to all of the proposed stages of T cell ontogeny, it appears that cytoplasmic expression of Leu-4 occurs early in T cell development. The reason for the failure of these immature T cells to transport the Leu-4 molecule to their surface remains to be elucidated.
M P
MP
Link
S J
SJ
Stewart
R A
RA
Warnke
R
R
Levy
D000945:Antigens, Differentiation, T-Lymphocyte; D000954:Antigens, Surface / Q000032:analysis*; D002648:Child; D003593:Cytoplasm / Q000276:immunology; D000939:Epitopes; D006801:Humans; D007945:Leukemia, Lymphoid / Q000276:immunology*; D008223:Lymphoma / Q000276:immunology*; D008970:Molecular Weight; D013601:T-Lymphocytes / Q000276:immunology*
D000945:Antigens, Differentiation, T-Lymphocyte; D000954:Antigens, Surface; D000939:Epitopes