Following M pneumoniae infection in children, B cells release antibodies and immunoglobulins, initiating a pathological immune response.[22] Among these, IgA serves as a primary immunoglobulin in preventing respiratory tract infections, IgG correlates closely with the progression and infection status of M pneumoniae in children, while IgM is among the earliest antibodies detected in humoral immunity. The gene discussed is CD40LG; the disease is infection.