This grant has for 25 years provided support for studies of immunodeficient patients. As part of this analysis, we have recently identified 2 groups of patients with common variable immunodeficiency (CVI), in whom abnormalities in lymphokine production appear to be a prominent part of their immunodeficiency. The first group (2 patients) shows a selective deficiency of IL-2 production, the second group (4 patients) a deficiency of several lymphokines including IL-2, interferon-gamma (IFN-gamma) and lymphotoxin. In each case deficient production of mRNA paralleled that for lymphokine protein. In Aim 1 of the current application we propose to examine in depth the basis for these defects. We hypothesize that the most common defect will be transcriptional. If so, we will determine if this reflects differences in factors acting in trans to regulate transcription of the IL-2 and for comparison the IFN-gamma genes. Differences in cis-regulatory sequences are possible, but seem unlikely except in the Group 1 patients with the deficiency restricted to IL-2 production. If the deficiency is not due to diminished transcription, we will explore abnormalities in mRNA processing or stability; this seems unlikely except in the patients with selective IL-2 deficiency. A signal transduction defect distal to the point which would be bypassed by calcium ionophores and PMA is considered possible in patients with multiple lymphokine deficiencies. This will be inferred if a deficiency in production of multiple activation induced trans-acting factors is found. Attempts will be made to partially dissect such a distal transduction defect. To perform these analyses we will utilize contemporary methodology, most of which is currently in routine use in our laboratories. Aim 2 capitalizes on another novel observation we have recently made in 2 adolescents with leukocyte adhesion deficiency. In both cases a small fraction of T cells express surface CD11/18 in amounts similar to controls. These cells have been established as long term T cell lines/clones and propagated for up to 2 months in culture with stable high-level expression of CD11/18. We hypothesize that this represents a reversion of the mutation on one allele of CD 18 (beta-chain) or an interchromosomal crossing over resulting in a normal allele. To test this hypothesis we will first determine that the 8 subunit/ precursor appear normal by immunoprecipitation of biosynthetically labeled CD11/18 + patient cells. If true, we will amplify by PCR and sequence the cDNA from these patients. The proposed studies will increase our understanding of the immunobiology of man and permit a precise identification of the molecular mechanisms in these patients.