Immunological monitoring of bone marrow transplant recipients

Abstract

In the recipients of an allogeneic HLA‐identical sibling transplant the blood leucocytes were reconstituted within 3 to 4 weeks but the level of lymphocytes remained low throughout the observation period of 20 weeks. Of the different lymphoid cell subsets, the large granular lymphocytes (LGL) reconstituted fastest, followed by DR‐expressing lymphocytes. The reconstitution was accompanied by a significant lymphoid blastogenesis in the blood. The frequency of OKT4 and OKT8 lymphocytes was initially low; the number of OKT8‐positive lymphocytes reached normal levels by the 6–8th week whereas the number of OKT4‐positive lymphocytes and, consequently, the OKT4/8 ratio remained low. The responses to the T mitogens, phyto‐haemmagglutinin and concanavalin A, were strongly suppressed. Only a few significant changes were observed before and during acute graft‐versus‐host disease (aGVHD): the frequency of LGL, lymphoid blasts and OKT8‐expressing lymphocytes was depressed before aGVHD and the frequency of lymphoid blasts remained depressed throughout the episode. We conclude that reproducible changes occur in the leucocyte subset frequencies during reconstitution, but the characteristic changes prior to and during aGVHD are not particularly prominent and hardly of diagnostic use.