Immunofluorescent patterns of spectrin in lymphocyte cell lines.

Spectrin, a membrane-associated cytoskeletal protein, has been observed in all of 45 lymphoid and myeloid cell lines examined. For these experiments, formalin-fixed cells from randomly selected lines propagated by using conventional tissue culture procedures were examined by immunofluorescence, using an antibody directed against chicken erythrocyte alpha-spectrin. Two distinct immunofluorescent patterns of spectrin distribution were identified. In most lines examined (16 mouse and 18 human lymphoid or myeloid lines), spectrin was symmetrically distributed near the submembranous region of the plasma membrane. In the remainder of the cell lines examined, a second pattern was observed; in these cultures, the cells contain a polar submembranous aggregate of spectrin with little staining at the rest of the plasma membrane. Long-term T lymphocyte cell lines in which greater than 60% of the cells expressed a polar submembranous aggregate of spectrin (PSA-S) include mouse cell lines EL-4, LBRM-33, CT-6X, NIXT, 22CM-37, and 7ON-2 and human lines JM and PEER. Other established cultures in which PSA-S were observed included the human macrophage-like line U-937 and gibbon T cell line MLA-144. Phorbol myristate acetate or mezerin caused a reversible alteration in the distribution of spectrin in these cell lines. These drugs, which increase membrane fluidity, caused a complete but temporary symmetrical redistribution of the spectrin aggregate. Our results indicate that the pattern of spectrin distribution, either aggregated or evenly dispersed, is a stable characteristic (but one that can be altered) in various cell lines, and that because similar variations in pattern have been noted in situ, it is likely that the pattern present in any given cell line reflects a characteristic associated with a particular stage of a cell's maturation. It is anticipated that these cell lines, positive and negative for the expression of natural polarity of spectrin distribution, will provide useful models for future studies to define further the role of spectrin in lymphocyte plasma membrane functions.