Immune complexes in myeloproliferative disorders.

A fluorescein-labelled anti-human immunoglobulin was used to demonstrate that peripheral blood from patients with myelofibrosis had a high proportion of phagocytic cells containing fluorescent immune complexes. Cells from patients with other myeloproliferative diseases (either chronic myeloid leukaemia or polycythaemia rubra vera) did not show similar intracellular immune complexes. Serum from patients with myelofibrosis incubated with polymorphs from healthy subjects caused the appearance of inclusions similar to those found when the patients' own cells were used, the healthy phagocytes apparently engulfing complexes from the patients' sera. The presence of platelets or complement did not alter the incidence of intracellular fluorescence. These tests may help in the diagnosis of myelofibrosis and may also be valuable in recognising the onset of this condition in patients with polycythaemia rubra vera.