Vitamin A deficiency diminishes the salivary immunoglobulin A response and enhances the serum immunoglobulin G response to influenza A virus infection in BALB/c mice.

We examined the effect of vitamin A deficiency on the secretory immunoglobulin (Ig) A and serum IgG response to influenza A virus infections in BALB/c mice. Mice fed a vitamin A-deficient (VAD mice) or a control diet were inoculated with influenza virus at 7 or 9 wk of age when serum retinol concentration had dropped to < or = 0.35 mumol/L in the VAD mice. The influenza-specific salivary IgA response to a mild infection (intranasal inoculation without anesthesia) was not significantly lower in the VAD group (5.3 +/- 2.1% of total IgA 4 wk after infection) than in the control group (10 +/- 11%, P > 0.05). In a separate experiment, this salivary IgA response was significantly lower in the VAD mice (0.3 +/- 0.4% of total IgA) following a more severe infection (intranasal infection while under anesthesia) than it was in control mice (4.2 +/- 4.6% of total IgA, P < 0.0001). In contrast, the concentration of total salivary IgA was uniformly greater in the VAD mice than in the control mice during both the mild infection (VAD, 17 +/- 6 mg/L vs. control, 8 +/- 11 mg/L at 3 wk, P < 0.0001) and the severe infection (VAD, 38 +/- 30 mg/L vs. control, 9 +/- 7 mg/L, P < 0.0001). Similarly, the influenza-specific serum IgG response was also greater in the VAD mice than in the control mice during both the mild infection (VAD, 194 +/- 91 mg/L vs. control, 79 +/- 95 mg/L at 5 wk, P = 0.0002) and the severe infection [VAD median, 202 mg/L (25th, 75th percentiles, 153, 409 mg/L) vs. control, 123 mg/L (42, 165 mg/L), P = 0.0023]. Thus VAD significantly impairs the secretory IgA response to influenza infection but modestly increases the serum IgG response to the same infection.