Differential expression of beta1 and beta2 integrins and L-selectin on CD4+ and CD8+ T lymphocytes in human blood: comparative analysis between isolated cells, whole blood samples and cryopreserved preparations.

Flow cytometric analysis was used to compare the expression of adhesion molecules on human CD4+ and CD8+ T lymphocytes in isolated blood mononuclear cells (MNCs) in whole blood samples and in cryopreserved MNC preparations. Examination of MNCs revealed that the CD11b and CD11c components of the beta2 integrins were preferentially expressed on CD8+ T cells, whereas CD62L was present on more CD4+ T cells. All CD4+ and CD8+ T lymphocytes were positive for CD11a but the CD8+ population had a higher intensity of expression of CD11a and also CD11b. Virtually identical results were obtained with T cells in whole blood samples. In relation to the beta1 integrins, the only difference between isolated CD4+ and CD8+ T cells was that the latter subset had a greater proportion of cells bearing CD49d. The naive cell marker CD45RA was present on the majority of CD8+ T cells whereas CD45RA and the memory marker CD45RO were evenly distributed within the CD4+ T cell subset. Although cryopreservation of lymphocytes did not modify the expression of beta1 and beta2 integrins it produced a marked reduction in the percentage of CD4+ and CD8+ T cells bearing CD62L. With regard to endothelial interactions, it appears that cryopreserved lymphocytes are suitable for inclusion in studies of integrin-mediated adhesion but not for those relating to tethering or recognition of addressins on high endothelial venules. Differences in adhesion molecule expression between CD4+ and CD8+ T lymphocytes could underlie the selective extravasation of these subsets into sites of infection and inflammation.

Antibodies from systemic lupus erythematosus (SLE) sera define differential release of autoantigens from cell lines undergoing apoptosis.

SLE is an autoimmune disease characterized by a wide range of anti-cellular and anti-nuclear autoantibodies. Many of these antigens are exposed or altered during apoptosis when the nucleus is dismantled in a controlled manner by caspases. We used Western blotting techniques to demonstrate that autoantibodies in SLE sera recognize antigens released during apoptosis. Reproducible bands, not seen in the untreated cells, with the characteristics of histones were seen when staining apoptotic cell lysates with SLE sera. Normal sera recognized some of these bands but much less strongly. Different triggers of apoptosis did not produce marked differences in the antigens recognized. We also compared different cell lines (Jurkat and U937) and found that the staining differed for one autoantigen in particular. The differential release of autoantigens by apoptotic cells may have relevance to the variety of autoantibodies seen in SLE.