Abnormal pattern of tyrosine phosphorylation in unstimulated peripheral blood T lymphocytes from patients with systemic lupus erythematosus.
Previous reports have shown abnormal responses mediated via the TCR/CD3 pathway in T lymphocytes from systemic lupus erythematosus (SLE) patients. Recently, we and others have reported augmented TCR/CD3-mediated responses in lupus T cells. It is possible that the pattern of downstream biochemical signals triggered by TCR/CD3 ligation may be altered in T lymphocytes from patients with SLE, thus leading to abnormal distal cell responses. In this paper we have examined the phosphorylation of proteins on tyrosine residues in peripheral blood T lymphocytes from a group of SLE patients and controls. We found a lower frequency of constitutively tyrosine-phosphorylated 119- and 113-kDa substrates and an enhanced frequency of tyrosine-phosphorylated 66- and 25-kDa proteins in unstimulated cultures of SLE T lymphocytes, suggesting an altered pattern of tyrosine phosphorylation in T cells from patients in vivo. Additionally, the protein tyrosine phosphatase (PTP) activity of CD45 immunoprecipitates was lower in unstimulated lupus T cells and was enhanced after stimulation via the CD3 pathway in lupus but not control T lymphocytes. The present results seem to suggest abnormal regulation of in-vivo tyrosine phosphorylation in T cells from patients with SLE.
Blasini
A M
AM
Centro Nacional de Enfermedades Reumáticas, Hospital Universitario de Caracas, Venezuela.
Alonzo
E
E
Chacón
R
R
Riera
R
R
Stekman
I L
IL
Rodriguez
M A
MA
D000293:Adolescent; D000328:Adult; D001798:Blood Proteins / Q000302:isolation & purification / Q000378:metabolism; D002478:Cells, Cultured; D002648:Child; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D006801:Humans; D008180:Lupus Erythematosus, Systemic / Q000097:blood / Q000276:immunology*; D008213:Lymphocyte Activation; D008297:Male; D008970:Molecular Weight; D010750:Phosphoproteins / Q000097:blood* / Q000302:isolation & purification; D010766:Phosphorylation; D019000:Phosphotyrosine / Q000097:blood*; D017027:Protein Tyrosine Phosphatases / Q000097:blood*; D017260:Receptor-CD3 Complex, Antigen, T-Cell / Q000502:physiology; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000276:immunology / Q000502:physiology*; D014443:Tyrosine
D001798:Blood Proteins; D010750:Phosphoproteins; D017260:Receptor-CD3 Complex, Antigen, T-Cell; D019000:Phosphotyrosine; D014443:Tyrosine; D017027:Protein Tyrosine Phosphatases