<prompt> A 7-month-old boy has had multiple bouts of otitis media, sinusitis, bronchitis, oral candidiasis, and multiple viral infections. Cessation of the recurrent infections follows successful engraftment of a bone marrow transplant. The basis of the clinical improvement isdirect transfusion of antibodyproducing B cells.direct transfusion of donor CD4 and CD8 lymphocytes.donor suppression of recipient cytotoxic T cellsmaturation of donor lymphoid progenitor cells  <response>: Severe combined immunodeficiency diseaseSCID Characterized by failure to thrive and increased susceptibility to bacterial, fungal, and viral infections. Laboratory studies reveal decreased numbers of both B cells and T cells and deficiency of immunoglobulins. The treatment of choice is bone marrow or other sources of hematopoietic stem cells transplantation and is based on maturation of donor lymphoid progenitor cells 