Microarray analysis of mRNA of chemokines and chemokine receptors. (A) mRNA clustergrams of genes and relative expression of mRNAs are shown for individual samples from purified B cells from controls (n = 4) and patients (n = 4). Color intensity changes from light green (low or absent expression) to black (average expression) and from black to intense red (maximum expression level). (B) mRNA expression clustergrams are shown after grouping the data from patients and controls. CXCL13 expression was up-regulated in all patient samples compared with controls. The mRNA levels for the CXCR4, CXCR5, CCR7, and the ligands CXCL12 and CCL21 showed no major differences. (C) CXCL13 is secreted from purified B cells after in vitro activation for 6 days. The levels found in patients (n = 15) were higher compared with controls (n = 15; P < .005). (D) Purified B cells from HIV-1 patients (n = 5) were cultured after in vitro activation (as above) with or without a neutralizing anti-CXCL13 Ab and CXCR5 expression (MFI) was measured. B cells cultured with the neutralizing CXCL13 Ab showed a higher CXCR5 expression compared with cells cultured with the isotype control Ab (P = .02).