Signal transduction in Sjögren's syndrome T cells. Abnormalities associated with a newly described human A-type retrovirus.
OBJECTIVE
To study the effects of a novel A-type retrovirus, detected in cocultures of lip biopsy specimens from Sjögren's syndrome (SS) patients and a human T cell line, on the infected T cells.


METHODS
Interleukin-2 (IL-2) and IL-6 secretion were measured by bioassay and enzyme-linked immunosorbent assay, respectively, in the infected and noninfected cell lines. Surface antigen expression was determined by flow cytometry, using monoclonal antibodies. Protein kinase C (PKC) activity was measured using an enzyme assay kit, and calcium mobilization was assessed with a fluorescent probe.


RESULTS
Infected cells expressed less CD4 and IL-6 receptor, but more HLA-DR, compared with noninfected cells. Infected cells also produced less IL-2 and displayed reduced PKC activation and calcium mobilization. A similar defect in calcium mobilization was detected in T cells from SS patients.


CONCLUSIONS
These data suggest a possible involvement of the newly described retrovirus in T cell abnormalities.
Flescher
E
E
Clinical Immunology Section, Audie L. Murphy Memorial Veterans Hospital, San Antonio, Texas.
Dauphinée
M J
MJ
Fossum
D
D
Ledbetter
J
J
Talal
N
N
D000945:Antigens, Differentiation, T-Lymphocyte / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D004789:Enzyme Activation; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D007376:Interleukin-2 / Q000096:biosynthesis; D015850:Interleukin-6 / Q000096:biosynthesis; D011493:Protein Kinase C / Q000378:metabolism; D012190:Retroviridae / Q000502:physiology*; D015398:Signal Transduction; D012859:Sjogren's Syndrome / Q000276:immunology / Q000378:metabolism* / Q000382:microbiology; D013601:T-Lymphocytes / Q000276:immunology / Q000378:metabolism* / Q000382:microbiology
D000945:Antigens, Differentiation, T-Lymphocyte; D007376:Interleukin-2; D015850:Interleukin-6; D011493:Protein Kinase C; D002118:Calcium