Low natural killer cell activity in the bone marrow of healthy donors with normal killer cell activity in the...

We have investigated the natural killer (NK) cell activity in peripheral blood and in bone marrow of nine normal donors. It was found that Ficoll-Hypaque (FH)-separated cells from the bone marrow collected in small (1 ml) aliquots had very low NK activity compared with normal activity in the peripheral blood of the same donor (mean +/- SD: 4.2% +/- 2.5% vs 25.1% +/- 15%, P less than 0.01). This difference was maintained for cells bearing receptors for sheep erythrocytes (E+) in both tissues (4.3% +/- 2.37% vs 15%+/-12.6%, P less than 0.01) or E- cells (2.5% +/- 2.86% vs 20.4% +/- 19.5%, P less than 0.01). Also, in bone marrow cells with Fc receptors for IgG (Fc gamma+) neither E+ nor E- had significant NK activity, in contrast to the peripheral blood, where significant NK cell activity was detectable in the Fc gamma + cells, either E+ or E- (1.9% +/- 1.2% and 1.3% +/- 1.4% vs 16.1% +/- 10.3% and 12.8% +/- 7.4%, respectively, P less than 0.01 for both). Our data indicate that bone marrow obtained with a low degree of blood contamination from normal donors has very low NK activity with no significant increase in any of the several fractions tested.