CD4+ T-cell-directed antibody responses are maintained in patients with psoriasis receiving alefacept:: Results of a randomized study

Background Alefacept, human LFA-3/IgG, fusion protein, selectively reduces memory-effector (CD45RO(+)) T cells, a source of the pathogenic mediators of psoriasis. Objective: To evaluate the effect of alefacept on immune function, T-cell-dependent humoral responses to a neoantigen (phiX174) and recall antigen (tetanus toxoid) were assessed. Methods: Patients with psoriasis were randomized to the control group or to receive alefacept (7-5 mg intravenously weekly for 12 weeks). The alefacept group received phiX174 immunizations at weeks 6, 12, 20, and 26 and tetanus toxoid at week 21; control subjects received phiX174 at weeks 6 and 12 and tetanus at week 10. Results. Mean anti-phiX174 titers were comparable in both groups. There was no difference in the percentage of responders (anti-phiX174 IgG greater than or equal to30% of the total anti-phiX174) between the alefacept group and the control group (86% and 82%, respectively; P =.73). The percentage of patients with anti-tetanus toxoid titer increases greater than or equal to2 times baseline also was similar (alefacept, 89%; control 91%). Conclusion. A single 12-week course of alefacept did not impair primary or secondary antibody responses to a neoantigen or memory responses to a recall antigen. The selective immunomodulatory effect of alefacept against a potentially pathogenic T-cell Subset is associated with maintenance of a significant aspect of immune function (antibody response) to fight infection and respond to vaccinations.