highly significantP < 0.0001
The decrease was highly significant for total B-cells between 6–18 months and 18 months to 4 years ( P < 0.0001) whereas the decrease in the numbers of CD27 + IgD + B-cells was not significant between 6–18 months and 18 months to 4 years ( P = 0.32) but was significant between 18 months to 4 years and 4–8 years ( P = 0.009).