The immune system in isolated IgA deficiency.

The immune systems were compared in 23 subjects with isolated IgA deficiency and 15 controls with normal levels of IgA. The IgA deficient group had higher levels of serum IgM, and lower stimulation indices for the mitogens Con A, PWM and PHA; only the index for PHA was statistically significant. Their suppressor T-cell activity was decreased and chemotactic activity significantly decreased. They also exhibited a decrease in Leu 3, and a significantly lower ratio of Leu 3 to Leu 2. The mean percent of positive NBT neutrophils was decreased. An imbalance in the immunoregulatory mechanism is suggested as a possible explanation for IgA deficiency.