HEMATOPOIETIC STEM-CELLS AND BASOPHILS

In a recent paper it was argued that all stem cells are small motile c ells, the haemopoietic stem cell being no exception. Although haemopoi etic stem cells arise and mature in an extravascular milieu, they are present in small numbers in the peripheral circulation, where they hav e a lymphocyte-like appearance, and in the peripheral circulation thei r fate can be linked to the development of basophils. The basophil is a cell shrouded in mystery, and one of the most mysterious aspects of the basophil is its small numbers in bone marrow, a finding which does not fit in with a marrow origin. A simple experiment provides an alte rnative explanation as to how they develop. If peripheral blood smears are prevented from drying out, after a few hours new basophils develo p from a lymphocyte-like cell. The findings suggest that the basophil may arise, not in the marrow, but in the peripheral circulation, and m ay represent an aberrant development of the haemopoietic stem cell cau sed by the plasma. The pathology of the basophil supports this view.