Background: Serum protein abnormalities, particularly elevated gamma globulins (hypergammaglobulinemia, HGG), have been reported in apparently healthy Nigerians living in Ogbomoso and elsewhere. Since the mechanisms for this phenomenon have not been fully substantiated, we hypothesized that impaired neutrophil phagocytosis could contribute to this condition.

Methods: Healthy humans exhibiting HGG were identified using serum protein electrophoresis performed on cellulose acetate gel in barbital buffer (pH 8.6). GelQuant image analysis and quantitation software were further employed to quantify the gamma globulin fraction. Neutrophils were isolated from K3EDTA anticoagulated peripheral blood using Histopaque neutrophil isolation reagent. Neutrophil phagocytic activity was analyzed using a non-subjective commercial colorimetric phagocytosis assay kit.

Results: The purity and viability of isolated neutrophils were approximately 94% and 92%, respectively. Ex-vivo phagocytic activity of neutrophils isolated from apparently healthy subjects exhibiting HGG, expressed as a percentage of the average absorbance of the control group, was 48.1 ± 8.6% which was significantly lower (p < 0.05) compared to the controls (98.9 ± 14.3%).

Conclusion: Since neutrophils play crucial roles in innate immune responses, impairment of neutrophil phagocytic activity may lead to persistent antigenic stimulations of the adaptive immune system. This could in turn orchestrate gamma globulins expression leading to HGG.

Statement of novelty: We demonstrated reduced neutrophil phagocytic activity as a possible basis for hypergammaglobulinemia in healthy Nigerians, perhaps for the first time.