Effects of arginine supplementation on the humoral and innate immune response of older people.

OBJECTIVE

To evaluate whether oral supplementation with arginine affects the humoral and innate immune response after vaccination against Streptococcus pneumoniae in a group of people aged 60 y and older, free-living in the community.

DESIGN

A randomized controlled trial with one supplemented group and one control group.

SETTING

Older persons living in the community.

SUBJECTS

A total of 29 adults aged 60 y and older.

INTERVENTIONS

The older people were randomized into two groups, one with arginine supplementation (15 g/day) for 4 weeks after pneumococcal vaccine. The control group received only the vaccine. Anthropometric measurements and immune system function parameters: neutrophil chemotaxis and phagocytosis, natural killer cell activity, determination of serum pneumococcal polysaccharide antibodies and serum C3 and C4.

RESULTS

Neutrophil phagocytosis and the serum concentration of complement (C3 and C4) did not differ between groups. IgG antibodies against pneumococcal polysaccharide serotypes 1, 5 and 6B increased in both groups. The following parameters increased in the arginine-supplemented group compared to the nonsupplemented group: neutrophil chemotaxis (34 vs 19 units of migration, P = 0.002), natural killer cell cytotoxicity (23.3 vs 13.4 10 M/Ul 40%, P = 0.011) and IgG against antigen 5 (12.3 vs 6.2 mug/ml, P = 0.044).

CONCLUSIONS

This study suggests that, after the pneumococcal vaccine, the intake of arginine increased neutrophil chemotaxis, natural killer cytotoxicity and serum concentration of IgG against antigen 5 in older people. These results suggest that arginine supplementation may enhance the immune response elicited by the pneumococcal vaccine in older people.

SPONSORSHIP

Supported in part by CAPES and FAEPA.