High-molecular-weight Ly-5 isoforms expressed on T cells: activation-dependent expression.
Interleukin 2 (IL-2)-dependent granular T lymphocyte (GTL) lines derived from murine spleen were shown to express a Ly-5 antigen with the so-called 'B220-epitope' recognized by 6B2 mAbs, which were normally exhibited on B-lineage cells. Immunoprecipitation analysis revealed that the Ly-5 isoform on GTL lines represented the highest-molecular-weight Ly-5 so far described (260 kd), distinct from the B220 isoform on a pre-B cell line (240 kd). The size difference between them was also evident after the endoglycosidase treatment (210 versus 190 kd), strongly suggesting that these Ly-5 isoforms had core proteins of distinct size. Sequential immunoprecipitation by 6B2 and 14.8 mAbs further indicated that the 260 kd Ly-5 on GTL lines predominantly expressed '6B2 epitope' while '14.8 epitope' dominated in the B220 (240 kd) on a pre-B cell line. Northern blot analysis of the Ly-5 transcripts using probes for the known alternative exons failed to show any evidence for mRNA of the 260 kd Ly-5 distinct from that of B220. Polymerase chain reaction analysis, however, suggested that the 260 kd isoform mRNA might be transcribed from a distinct promoter with a yet undefined exon(s). The 6B2+ Ly-5 isoform was hardly detected on normal splenic T cells, but was shown to be induced rapidly on the majority of T cells following IL-2 stimulation in vitro, indicating that this particular Ly-5 isoform behaved as an 'activation antigen' on T cells.(ABSTRACT TRUNCATED AT 250 WORDS)
Ogawa
Y
Y
Biomaterial Research Institute, Yokohama, Japan.
Okazaki
H
H
Sudo
T
T
Ohno
N
N
Itoh
M
M
Hattori
M
M
Iizuka
M
M
Minato
N
N
D000818:Animals; D000911:Antibodies, Monoclonal; D000950:Antigens, Ly / Q000737:chemistry / Q000235:genetics; D001402:B-Lymphocytes / Q000276:immunology; D002460:Cell Line; D004247:DNA / Q000235:genetics; D000939:Epitopes; D006412:Hematopoietic Stem Cells / Q000276:immunology; D007376:Interleukin-2 / Q000494:pharmacology; D008213:Lymphocyte Activation; D008970:Molecular Weight; D013601:T-Lymphocytes / Q000276:immunology*
D000911:Antibodies, Monoclonal; D000950:Antigens, Ly; D000939:Epitopes; D007376:Interleukin-2; D004247:DNA