Cycling of peripheral blood and marrow lymphocytes in cyclic neutropenia

A 16-month-old male patient with cyclic neutropenia was found to have cyclic fluctuations of monocytes, lymphocytes, platelets, and eosinophils in the peripheral blood. Changes in lymphocyte counts were not obviously related to B, T, or natural killer cells. All classes of immunoglobulins were elevated throughout the cycle. Studies of the marrow morphology revealed remarkable cyclic oscillations of lymphoid as well as myeloid lineage cells. Granulocyte-macrophage progenitors (CFU-c) cycled and were virtually absent 1 wk prior to the neutropenic nadir. The cyclic changes in marrow lymphoid cell numbers were primarily due to changes in numbers of surface immunoglobulin negative (sIg-), cytoplasmic Ig+ (cIg+) pre-B cells. Pre-B cell numbers cycled from normal to extraordinarily elevated values with the same periodicity but reciprocal to the neutrophil cycle. We propose that the primary defect in cyclic neutropenia may either be a periodic failure of an early myeloid differentiation factor or a blunted response of early myeloid precursors to a common hemopoietic growth factor. This may lead to periodic fluctuations in the production or delivery of growth factors (or factor) that influence early stages of differentiation of other hemopoietic cells, including pre-B cells. The essential periodic deficiency is consequently reflected in deficient production of CFU-c accompanied by excessive production or accumulation of pre-B cells (and probably other hemopoietic precursors) in the marrow.