CD3+, 4+ and/or 8+ T cells and CD3+, 4-, 8- T cells repopulate at different rates after allogeneic bone marrow transplantation

The antigen receptors of the majority of peripheral blood T lymphocytes are constituted of alpha- and beta-chains in association with CD3. The phenotype of those T cell receptor-alpha, beta cells is CD3+, 4+ and/or 8+. The small subset of CD3+, 4-, 8- T cells includes TCR-gamma, delta cells. These two T cell subsets have different TCR gene rearrangement patterns, tissue distributions and mechanisms of antigen recognition. We studied the repopulation of both T cell subsets in 20 allogeneic marrow graft recipients in relation to the type of graft (T cell-depleted versus non-depleted) and the occurrence of active cytomegalovirus (CMV) infection, using three-color immunofluorescence and flow cytometry. The CD3+, 4+ and/or 8+ and CD3+, 4-, 8- T cells had clearly different repopulation patterns. At 1 month post-BMT, they had repopulated the blood to similar levels. Thereafter, the CD3+, 4+ and/or 8+ T cells increased further in number, whereas the CD3+, 4-, 8- T cells stabilized on average between 100 and 200 x 10(6)/l. The nine recipients of T cell-depleted marrow grafts showed a relatively delayed repopulation of their CD3+, 4+ and/or 8+ T cells compared with the 11 recipients of non-depleted marrow. In contrast, the repopulation rate of the CD3+, 4-, 8- T cells was similar in both groups. The occurrence of active CMV infection post-BMT was associated with an increased rate of repopulation of the CD3+, 4+ and/or 8+ T cells, particularly those expressing HNK1, but did not affect the repopulation of the CD3+, 4-, 8- T cells.