Strong alpha beta and gamma delta TCR response in a patient with disseminated Mycobacterium avium infection and lack of NK cells and monocytopenia

Infection with atypical mycobacteria occurs mainly in patients with a compr omised cellular immune system, in particular in those with a defective T ce ll or monocyte function. Here we analyzed the specific immune response of a n adolescent HIV-negative patient with disseminated mycobacterium avium inf ection and fatal varizella tester virus infection. The patient presented wi th dysplastic hematopoesis of all cell lineage's and a bicytopenia of eryth rocytes and leukocytes, but a hematological malignancy could not be found. We found a peripheral lymphopenia and monocytopenia, as well as a lack of N K-cells and B-cells. Lymphocytes consisted of 95% T cells, which contained up to 40% of TCR gamma delta + CD4-CD8-T-cells (mainly TCR gamma 9 delta 2) , few monocytes and B-cells. Approximately 50% of CD3+ T-cells showed a CD5 7+ NK-like phenotype. Functional analysis of PBMC revealed a good antigen-s pecific T cell function if antigen-presenting cells were supplemented from a HLA-matched donor. Moreover, a strong M. avium specific cytotoxicity medi ated by TCR alpha beta + T-cells could be found in vitro and even ex vivo. In contrast, NK-killing was absent. No evidence for a defect in IL-12 or IF N-gamma production and signaling were found. The data indicate that a stron g alpha beta and gamma delta T cell immunity tries to compensate for a defi cient monocyte and NK cell Function in this patient. (C) 2000 Elsevier Scie nce B.V. All rights reserved.