Since stop codons in various genes show a broad spectrum of readthrough efficiency in response to gentamicin, the extent of increase in CD18 expression that followed this treatment was surprisingly high. For example, patients with muscular dystrophies and cystic fibrosis were shown to have readthrough levels of the affected gene Doxorubicin ranging from only 0.05% to 2.65%. Despite the significant elevation in the expression of the corrected CD18, only a slight change in the cell surface expression of the heterodimer CD11/18 was demonstrated in lymphoblasts after gentamicin treatment, as demonstrated both by FACS analysis and immunofluorescent studies of these cells. This non-functional expression of the heterodimer may explain the failure or the relative difficulty to obtain significant changes in leukocyte functions. CD18 expression is required for the normal expression of the CD11 components of the heterodimers, yet their expression does not confirm function. Differences in CD18/CD11 expression in LAD1 patients due to the different homeostasis of their leukocytes have never been addressed before. By testing the effect of gentamicin on the CD18 level, we could also determine the effect of the corrected CD18 on the proper cell surface expression of the different CD11 molecules and the integrity of the entire CD18/11 complex. Interestingly, while CD11b and CD11c were positively affected by the increased level of CD18, CD11a remained undetectable by FACS analysis. Therefore, we can speculate that a gentamicin-induced readthrough has an effect on CD18 expression which allows its ability to associate with the CD11b and CD11c subunits but not with the CD11a subunit at the cell surface. We hypothesize that the inability of the corrected CD18 to bind CD11a is due to the gentamicin induced replacement of tryptophan residue instead of the wild type arginine at amino acid position 188 of CD18 protein, as suggested also by our computerized modeling analysis of the predicted heterodimer. While the truncated CD18 protein that resulted from the premature stop codon was either degraded or misfolded and therefore dysfunctional, it is likely that the corrected CD18 was not properly folded because the tryptophan replacement is not located in the protein core. Since there is no available structure to depict the CD18/CD11 complex, our proposed model and its orientation with respect to the CD51/CD61 resolved complex suggests that the tryptophan is located close to the interface and might interact with or sterically disturb any interaction with its alpha chain partners, such as CD11a. In any event, the charge difference might affect binding, even in longer range interactions. Since we could not significantly affect the neutrophil function despite elevating the expression of CD18, CD11b and CD11c.