Flow cytometric immunophenotyping in the diagnosis and follow-up of immunodeficient children

From time to time, paediatricians are confronted with children who might su ffer from a primary immunodeficiency disease. For practical purposes, these children can be divided into four main clinical categories: (1) a relative ly large group of children with recurrent ear-nose and throat and lower res piratory tract infections, in some cases caused by deficiencies of antibodi es or complement; (2) children with failure to thrive, intractable diarrhoe a or an opportunistic infection which can be caused by a T-lymphocyte or co mbined immunodeficiency; (3) children with infections with pyogenic bacteri a or fungi as seen in case of granulocyte/monocyte function deficiency; and (4) a small heterogeneous group of children with recurrence of particular infections. Also, acquired immunodeficiency becomes a more common problem i n paediatric practice. Flow cytometric immunophenotyping of leucocytes appe ars to be an efficient and rapid tool in the diagnosis and followup of immu nodeficient patients, supporting early recognition, before serious infectio ns have compromised the child's general condition. This technique can now b e performed in many hospitals. In this review, we give directions for the u se of flow cytometric immunophenotyping of leucocytes in the diagnosis and follow-up of immunodeficient children according to the four main clinical c ategories.