Prevalence of Immunoglobulin G (IgG) antibodies to the merozoite-surface protein-1 (42) (MSP-1₄₂) in highland Kenyan adults in 2008 and 2009.

<p>McNemar’s test, <i>P</i> = 0.32.</p

The gating strategy for identifying the B cell subpopulations.

<p>We first gated on the live (DAPI⁻) lymphocytes and then collected 10,000 events of CD19+. These were analyzed for expression of IgD, CD27, CD21, IgM and FcRL4. CD19+ lymphocytes were classified as naïve (IgD+CD27-) B cells, non class-switched (IgD+CD27+) MBCs, classical (IgD-CD27+) MBCs and double negative (IgD-CD27-) MBCs. MBC subtypes were further defined as follows: 1. Resting classical MBCs: CD19+IgD-CD27+CD21+. 2. Activated MBCs: CD19+IgD-CD27+CD21-. 3. Atypical MBCs: CD19+IgD-CD27-CD21- MBCs.</p

Proportion of B cells and B cell subsets in 2008 and 2009.

<p>The mean percentages of total (CD19+) B cells (A), classical (CD19+IgD-CD27+) MBCs (B), non-class switched (CD19+IgD+CD27+) MBCs (C), naïve (CD19+IgD+CD27-) B cells (D) and double-negative (CD19+IgD-CD27-) MBCs (E) over the study period.</p

Number and percentages of responders to tetanus toxoid (TT) as assessed by specific memory B cells and immunoglobulin G (IgG) antibodies (Ab) in April 2009.

<p>McNemar’s test, <i>P = </i>0.71.</p

The proportions of marginal zone (CD19+IgD+CD27+IgM+) B cells increased between 2008 and 2009.

<p>The proportions of marginal zone (CD19+IgD+CD27+IgM+) B cells increased between 2008 and 2009.</p

The distribution of FcRL4+ memory B cell subsets.

<p>The percentage of FcRL4+ CD19+IgD-CD27-CD21 MBCs had a non-significant increase (A) but the mean fluorescence intensity (MFI) of FcRL4+ cells increased significantly (B). Lines in 7A reflect mean values and comparison is with t-test. Lines in 7B reflect median values and comparison is with Wilcox on signed rank test because MFI values were not normally distributed.</p

The distribution of class-switched memory B cell subsets in adults from highland Kenya.

<p>Mean percentages of: (A) class-switched resting classical (CD19+IgD-CD27+CD21+IgM-) MBCs, (B) class-switched activated classical (CD19+IgD-CD27+CD21-IgM-) MBCs, (C) class-switched CD19+IgD-CD27-CD21+ and (D) class-switched atypical (CD19+IgD-CD27-CD21-IgM-) MBCs.</p

Comparison between estimated memory B cell frequencies and antibody responses to merozoite surface protein-1₄₂ (MSP-1₄₂) and tetanus toxoid (TT).

<p>There was no association between specific MBCs and antibodies for both MSP-1₄₂ and TT in 2008 and 2009.</p

Prevalence of toxoid (TT)-specific immunoglobulin G (IgG) antibodies in highland Kenyan adults in 2008 and 2009.

<p>McNemar’s test, <i>P</i> = 1.0.</p

Number and percentages of responders to merozoite-surface protein-1 (42) (MSP-1_42, as assessed by antigen-specific memory B cells and immunoglobulin G (IgG) antibodies (Ab), in 2008.

<p>McNemar’s test, <i>P = </i>0.0005.</p