Adult-onset cyclic neutropenia is associated with increased large granular lymphocytes

Human cyclic neutropenia occurs in adults as well as children. Clinical illness is similar in the childhood and adult diseases, but distinctly different modes of onset suggest heterogeneity in its pathophysiology. We studied seven patients with cyclic neutropenia, three with disease acquired in adulthood, and four with the childhood-onset disorder. All three patients with adult-onset cyclic neutropenia had increased numbers of circulating large granular lymphocytes (LGL), whereas the four children with cyclic neutropenia had normal LGL counts. LGL from patients with adult-onset cyclic neutropenia expressed cell surface antigens HNK-1 (three of three patients) and IgG Fc receptors (two of three patients), although natural killer activity was low. Two of these patients were treated with alternate-day steroids, resulting in decreased LGL counts and abrogation of neutrophil cycling. We suggest that adult-onset cyclic neutropenia may be distinguished from the childhood-onset form of the disease by increased numbers of LGL. Furthermore, increased LGL may identify a subset of patients with cyclic neutropenia who respond to steroid therapy.