laboratory findings: significant decrease in complement components 3 and 4, elevated levels of IgG (32 g/L) and IgA, normal IgM and IgG4 subclass levels, lymphopenia in flow cytometry (decreased T lymphocyte counts, including cytotoxic T cells and NK cells, reduced percentage of memory T cells, normal percentages of recent thymic emigrants and regulatory T cells, slightly reduced percentage of switched memory B cells, increased percentage of IgM-only memory B cells, slightly elevated percentage of double-negative T cells. Here, CD40LG is linked to lymphopenia.