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.