[Antibodies against granulocyte precursors in patients with neutropenia: use of the ML-1 myeloid line].

With the aid of indirect immunofluorescent test, the authors investigated antibodies in the serum of patients, which reacted against immature myeloid cells and mature granulocytes. Myeloid line ML-1, longitudinally maintained in vitro, was used as source of immature myeloid cells. 248 sera were examined and antibodies against the immature myeloid cells were detected in 8% of them. In 6 selected sera of the patients with neutropenia, the authors determined the Ig class of the identified antibody against the immature cells of the ML-1 myeloid line, against the myeloid cells of the ML-1 line differentiated with retinoic acid, respectively even the Ig class of the antibody against neutrophils. The IgM class antibody was found to have the highest frequency. Using absorption studies, the authors provided evidence that the antibody against the myeloid cells can be absorbed only by means of the cells of the myeloid line ML-1, which is demonstrated by the absence of the surface character in the mature neutrophils against which the antibody was directed. The authors discuss the outcome of their investigation aimed at making a more accurate diagnosis of immune neutropenia.