Peripheral blood lymphocyte subpopulations in polycythaemia and thrombocythaemia.

Lymphocyte subpopulations from peripheral blood of normal subjects and patients with primary proliferative polycythaemia (PPP), idiopathic erythrocytosis (IE) and essential thrombocythaemia (ET) were separated using antihuman immunoglobulin antiserum for B lymphocytes and the following monoclonal antibodies: OKT3, directed against the general T-lymphocyte subpopulation, OKT4 and OKT8, detecting respectively T-helper and T-suppressor lymphocyte subpopulations, OKM1 reacting mainly with monocytes. A decrease in the number of OKT3+ cells was observed both in PPP and IE, with a particular fall of the OKT8+ (suppressor) cells, so that the T4/T8 ratio was significantly increased (P less than 0.03 in PPP and P less than 0.0005 in IE). The ratio remained normal in samples from ET. OKM1+ cells were significantly increased in PPP (P less than 0.04), but not in IE, while in ET there was a rise in a few cases only. The present data point out some definite changes in the circulating lymphomonocytic cell subsets, which may be of interest in the study of this group of myeloproliferative disorders.