Cellular basis for the elevated gallium-67 computed lung index in a rheumatoid lung patient

A patient with high levels of serum rheumatoid factor and an open lung biopsy which showed high-grade interstitial pneumonia with large numbers of lymphocytes and plasmocytes had intense gallium uptake in the lungs. Lymphocytes and/or plasmocytes might be responsible for the gallium uptake even though neutrophils are usually credited with high-level uptake. Differential cell counts demonstrated plasmocyte and lymphocyte preponderance, but neutrophil paucity. In vitro cell cultures of purified neutrophils, monocytes, leukemic plasmocytes, and resting and stimulated lymphocytes with 67Ga showed that plasmocytes take up comparatively low levels of 67Ga, but that activated lymphocytes take up levels that approach neutrophils. It is probable that both rheumatoid lung plasmocytes and activated lymphocytes are responsible for the pulmonary 67Ga concentration in this patient.