Influence of obesity on immune function.

OBJECTIVE: To compare immune function in obese and nonobese subjects.

DESIGN: Obese and nonobese subjects were compared cross-sectionally. To test for the influence of other factors on immunity, aerobic fitness, psychological well-being, and serum levels of glucose, triglycerides, and cholesterol were measured and included in multiple regression models to determine their comparative effects.

SUBJECTS/SETTING: Community-based subjects included 116 obese women (age = 44.3 +/- 9.7 years, body mass index = 33.2 +/- 6.5) and 41 nonobese women (age = 42.2 +/- 10.9 years, body mass index = 21.2 +/- 1.9).

STATISTICAL ANALYSES PERFORMED: Independent t tests, Pearson product moment correlations, and stepwise multiple regression procedures.

RESULTS: Obesity was linked to elevated leukocyte and lymphocyte subset counts (except for natural killer and cytotoxic/suppressor T cells), suppressed mitogen-induced lymphocyte proliferation (an index of T- and B-cell function), higher monocyte and granulocyte phagocytosis and oxidative burst activity, and normal activity of natural killer cells.

APPLICATIONS/CONCLUSIONS: These data support the contention that obesity is associated with alterations in immune function. Further research is needed to link immunosuppression with the previously reported elevated risk of infection among the obese.