T-cell independent production of salivary secretory IgA after hematopoietic stem cell transplantation in children

This study examined the recovery of secretory IgA (S-IgA) in saliva after hematopoietic stem cell transplantation (HSCT) in 35 children and young people between the ages of 3 and 27 years (mean = 13.6), and compared this recovery with that of serum immunologic constituents. Reference values for human salivary S-IgA in saliva were obtained from 77 healthy control subjects between the ages of 7 and 25 years (mean = 11.4). In the 35 patients, a nadir of secretory IgA concentrations in saliva (S-IgA) was observed between the 3rd and the 4th month, and a return to normal values 1 year after HSCT. Serum IgA concentrations reached their nadir in the 6th month, and normalized in the 18 months after HSCT. The recovery of T-helper cells (CD4⁺/3⁺) was also delayed to beyond 18 months. We found a significant correlation between the reconstitution pattern of S-IgA and that of T-helper lymphocytes, but no correlation was found between the post-transplant evolutions of S-IgA and serum IgA, or between S-IgA and T-helper cells. The recovery of S-IgA was more rapid than that of serum IgA and appeared to be T-helper cell independent.