Expansion of a minor subpopulation of peripheral blood lymphocytes (T8+/Leu 7+) in patients with haemophilia.

Immunological analysis of peripheral blood mononuclear cells (PBM) was performed in 20 patients with haemophilia A or B. One of the patients had never received clotting factor substitution in his life. Six different sources of lyophilized clotting factor were used for the other patients, but every given patient received factor from one source, exclusively. None of the patients exhibited lymphadenopathy and only one suffered from local bacterial infection. Mononuclear cell counts were within the normal range and mitogen stimulation with phythaemagglutinin (PHA) and concanavalin A (Con A) was found normal in all but two patients. Ratios of helper and suppressor cells (T4/T8) were below 1·0 in 10 of the patients. Some of these patients had a relative increase of T8+ cells and at the same time of Leu 7+ (natural killer (NK)/suppressor) cells. Double-marker analysis revealed that the subpopulation of cells expressing both the T8 and the Leu 7 antigen, which on the average accounted for 2·1% of the mononuclear cells in controls, was increased 4·5 fold (9·1%) in haemophilia patients. One patient exhibited 37·8% T8+/Leu 7+ double-marker cells. VEP13+ cells (active NK cells) were decreased below the normal range in 11 of the patients. Abnormal values for lymphocyte subsets were found in every treatment group. The patient who had never received any clotting factor exhibited normal values in all respects. In an additional set of patients, those with increased percentage of T8+/Leu 7+ cells exhibited decreased NK cell activity indicating that the T8+/Leu 7+ cells are not active NK cells. The expanded subpopulations of T8+/Leu 7+ double-marker cells described in this report might represent an important immunoregulatory subset, and deserves further study in patients with immunodeficiency. Seropositivity for human T-cell leukaemia virus (HTLV-III) was detected in six of 18 sera tested. The presence of antibody, however, did not correlate with any of the immunological abnormalities, including the expanded T8+/Leu 7+ double-marker cells.