MOLECULAR-BASIS OF A MULTIPLE LYMPHOKINE DEFICIENCY IN A PATIENT WITHSEVERE COMBINED IMMUNODEFICIENCY

We have previously reported that the T lymphocytes of a child with sev ere combined immunodeficiency are defective in the transcription of se veral lymphokine genes that include IL2, IL3, IL4, and IL5, which enco de interleukins 2, 3, 4, and 5 (IL-2, -3, -4, and -5). To determine wh ether the defect in the patient's T lymphocytes involved a trans-actin g factor common to the affected lymphokine genes, we examined the abil ity of nuclear factors from the patient's T lymphocytes to bind respon se elements present in the regulatory region of IL2. Nuclear factor NF -kB, activation protein 1 (AP-1), OCT-1, and NF-IL-2B binding activity were normal. In contrast, the binding of the nuclear factor of activa ted T cells (NF-AT) to its response element in the IL2 enhancer and to an NF-AT-like response element present in the IL4 enhancer was abnorm al. To ascertain whether the abnormal NF-AT binding activity was relat ed to an impaired function, we transfected patient and control T lymph ocytes with constructs containing the reporter gene encoding chloramph enicol acetyl transferase (CAT) under the control of the entire IL2 re gulatory region or of multimers of individual enhancer sequences. CAT expression directed by the IL2 regulatory region or by a multimer of t he NF-AT-binding site was markedly lower in the patient relative to co ntrols. In contrast, CAT gene expression directed by a multimer of the OCT-1 proximal (OCT-1p)-binding site was equivalent in patient and co ntrols. These results indicate that an abnormality of/or influencing N F-AT may underlie the multiple lymphokine deficiency in this patient.