Complete functional B & T cell deficiency

• In X - linked SCID T cells & NK cells fail to develop
• IL - 7 & IL - 15 are cytokines essential for the development of T cell progenitors & NK cells
• Adenosine deaminase deficiency is a genetic cause of SCID
• Type II bare lymphocyte syndrome is due to a MHC class II deficiency causing a defect in the development of CD4+ cells in the thymus
• Type I bare lymphocyte syndrome is due to a MHC Class I deficiency causing a CD8+ T cell deficiency
• Ppts with MHC class I deficiency has characterising necrotising skin lesions on the extremities & the midface due to activated NK cells