CD40LG and vitamin D deficiency: When comparing immunoglobulin levels in children with deficient or insufficient vitamin D levels to those with optimal vitamin D levels, it was found that children with vitamin D deficiency/insufficiency more frequently exhibited elevated levels of IgA (55.2% vs. 29.6%), IgM (79.3% vs. 51.9%), IgG (17.2% vs. 11.1%), and IgE (44.8% vs. 12.0%).