Reduced helper (OKT4+): suppressor (OKT8+) T ratios in aplastic anaemia: relation to immunosuppressive therapy.

T cell subset composition of peripheral blood and bone marrow from 22 patients with aplastic anaemia (AA) was studied by monoclonal antibodies (OKT3, OKT4 and OKT8). In the peripheral blood, OKT3 (pan-T), OKT4 (helper/inducer-T) and OKT8 (suppressor-T) cells varied widely in number. The ratios of OKT4:OKT8 exhibited the same tendency. However, a subgroup of AA with a reduced ratio of lower than 1.0 was present both in cases with or without prior prednisolone therapy. Of the eight patients treated with immunosuppressants, four with reduced ratios responded, whereas the other four with normal or higher ratios did not. The ratios of two of four responders gradually reached the normal level. These results suggest that the reduced OKT4:OKT8 ratio may be related to the cell-mediated immunosuppressive mechanism postulated as a cause of stem cell inhibition in a subgroup of AA, and indicate prospectively the effectiveness of immunosuppressive therapy.