Hernández MP., Prieto A., Carrión F., Reyes E., Zea A., Perez-Machado MA., Alvarez-Mon M.

Department of medicine. University of Alcala. Clinical immunology service. Principe de Asturias University Hospital. Alcala de Henares. Rheumatology service. Hospital Ramon y Cajal. Madrid (Spain).

T cells from SLE patients show an altered proliferative response to ployclonal mitogens. Several mechanisms have been described to explain this phenomenon but no common T cell intrinsic defeat has been found.

Materials and methods : CD2+ cells were obtained from peripheral blood by rosetting technique. Subpopulational viability assays : Cells were cultured during 5 days stopped at different times and stained with anti-CD4 FITC/anti- CD45RO PE and anti-CD45RA FITC/anti-CD45RO PE; and incubated for 30 min at 4§C and resuspended in PBS. After two washed, PBS containing 7aminoactinomicin D (7aaD) at a final concentration of 1þg/ml was added and incubated for 3 minutes before FACScan analysis. Determination of apoptotic cells : PHA stimulated lymphocytes were treated to extract low molecular weight DNA from nuclei of apoptotic cells at different times during the 48h. DNA was stained with Propidium Iodide.

Results : Different levels of CD45RO+ lymphocytes were found in CD2+ cells from SLE patients. The percentages of CD45RO+ viable cells in phytohemagglutinin stimulated CD2+ cultures of lymphocytes from five SLE patients at different interval times studied were lower than those of CD45RA+lymphocytes found in the same cultures. At earlier times in the culture the percentages of nuclei with reduced DNA content in lymphocyte cultures from SLE patients were higher than those found in cultures of lymphocytes from the healthy controls; thus suggesting an early apoptotic cell death mechanism for the SLE lymphocytes.

Conclusions : 1) SLE patients T lymphocytes display in vivo activation. 2) This activation of T cells with subsequent decrease in the viability of CD45RO+ cells appears to be involved in the biological basis of their altered proliferative response to mitogens. 3) Viability data from CD45 subpopulations demonstrates that CD45RO+ cells die after activation and a mechanism of apoptosis appears to be involved.