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.