Defective neutrophil migration in monosomy-7

The migration in vitro of neutrophils from six patients with monosomy-7 or partial deletion of the long arm of chromosome 7 was studied by two methods: the Millipore filter assay and the migration under agarose assay. Four of the patients had preleukemia, one had subacute myelomonocytic leukemia, and one polycythemia vera. In four patients, chemotaxis (migration towards a higher concentration of chemoattractant) and chemokinesis (stimulated migration without a gradient) were shown to be defective by both methods. In the remaining two patients, this defect could be demonstrated only by the Millipore filter assay or by the agarose assay. Under agarose, random locomotion (no chemoattractant present) of the patients' neutrophils was less than that of the control subjects in four patients, whereas no clear difference could be shown by the Millipore filter method. This study demonstrates that the previously described defect of neutrophil migration in monosomy-7 involves not only chemotaxis but all stimulated migration and, at least in some patients, random locomotion as well. Defective migration in two patients with an apparently terminal deletion of the long arm of one chromosome 7 indicates that the distal half of 7q carries genetic material important for neutrophil locomotion.