Question

The DiGeorge's Syndrome (or, congenital thymic hypoplasia), results from the faulty development of the third and fourth pharyngeal pouches during embryogenesis. Upon birth, the children who demonstrate this malady also suffer from hypocalcemia due to a parathyroid deficiency (a pharyngeal pouch III derivative). And, while the cell-mediated immunity in these children is, obviously, impaired, their circulating levels of antibody, at least to certain antigens, may be below normal. Explain why you think this may occur? Additionally, a fetal thymus transplant into these children has been shown to be capable of producing a permanent reversal of the T-cell deficiency in these patients---without provoking a "Host vs Graft" or a "Graft vs Host" rejection reactions. Can you explain why this is possible?

Answer 1

These patients won't have thymus. thymus is the region where the T cells mature. T cell maturation is the process by which the T cells learn to recognise the self tissue and foreign tissue. Tcells are involved in cell mediated immunity.cell mediated immunity doesn't involves antibody but the antigen specific cytotoxic mature Tcells. as there is no thymus there will be no mature T cells.

Transplantation is process by which reciepient recieves donor's healthy organ or cell. the reciepient body will recognise the cells from the donor as foreign body and immune system will response to eject these cellsor organ from the body. This is graft rejection and mediated through T cells which can recognise foreign and self cells.In case deGeorge syndrome patients as there is no mature Tcells there will be nograft rejection.