High inducibility of heat shock protein 72 (hsp72) in peripheral blood mononuclear cells of aplastic anaemia patients: a reliable marker of immune-mediated aplastic anaemia responsive to cyclosporine therapy

To better characterize immunologic aberrations in aplastic anaemia (AA), we examined peripheral blood mononuclear cells (PBMC) of 67 patients with AA and other patients with various haematological diseases for the expression of heat shock protein 72 (hsp72), which is inducible in lymphocytes by vari ous stressors including antigenic stimulation. When freshly obtained PBMC w ere examined using flow cytometry, the proportion of cells expressing hsp72 in cytoplasm was significantly higher in allogeneic marrow transplant reci pients (22 +/- 15%, mean +/- standard deviation (SD)) and AA patients (17 /- 21%) than in normal individuals (6 +/- 3%), When PBMC were tested after heat treatment, only the proportion of hsp72(+) cells of AA patients (37 +/ - 30%) was significantly higher than that of the normal control (17 +/- 11% ), Dual fluorescence analysis of the PBMC revealed that the majority of hsp 72(+) cells was CD3(+), For 28 untreated AA patients, the proportion of hsp 72(+) cells in those who later responded to cyclosporine (CyA) (62 +/- 24%) was higher than that in non-responders (19 +/- 13%), Immunoblotting analys is revealed predominant expression of hsp72 in T cells. These findings indi cate that high inducibility of hsp72 in PBMC by heat treatment is an immuno logic aberration characteristic of CyA-responsive AA and that this simple t est may be useful for identifying a subset of AA patients responsive to imm unosuppressive therapy.