[Presence of alpha-2-macroglobulin on the membrane of peripheral human blood lymphocytes : a new lymphocyte maker].

The presence of alpha-2-macroglobulin (alpha-2-M) on the surface of peripheral blood lymphocytes from normal human subjects and from patients with chronic lymphatic leukaemia (CLL) and with ataxia-teleangectasia was studied by indirect immunofluorescence technique. Same experiments were done on purified subpopulations of normal blood peripheral lymphocytes (B and T). The percentage of alpha-2-M bearing lymphocytes is 17 +/- 6% as regard to normal subjects (Ig-bearing cells are 14%): in CLL the percentage of alpha-2-M bearing cells generally is significantly lower than that of Ig-bearing cells (IgM-IgD). On selected subpopulations, 90% of alpha-2-M bearing cells are present among non T-cells and only 5% among T-cells (probably due to not absolute purification). Blocking experiments using anti-Ig sera did not affect significantly the percentage of alpha-2-M bearing cells and using anti-alpha-2-M sera did not affect that of Ig-bearing cells. The percentage of E-rosette forming cells is not affected by pretreatment of peripheral lymphocytes with anti-Ig and/or anti-alpha-2-M sera. Hypothesis is set forth that alpha-2-M bearing cells could be a lymphocytes subpopulation made by a subgroup of B-cells and by K-cells, taking part in that immunoregulatory system in which collaborate many serum alpha-globulins and T-suppresor cells.