Furthermore, our results suggest that monitoring the Ig subclasses of sICs or the percentage of sIC+ rCD4s may also be useful for determining the stage and progression of HIV-1 infection (Fig. 2A) because during acute infection, sICs largely consisted of IgM, and the percentage of sIC+ rCD4s gradually increased during the follow-up period (approximately 3 yrs) (Fig. 2A). This evidence concerns the gene CD40LG and HIV-1 infection.