Residual cancer lymphocytes in patients with chronic lymphocytic leukemia after therapy show increased expression of surface antigen CD52 detected using quantitative fluorescence cytometry.

BACKGROUND: Rituximab and alemtuzumab, mAbs used in recent years to treat CLL, are directed against antigens CD20 and CD52. CD20 is not highly expressed by CLL tumor cells, and rituximab does not have significant effectiveness in CLL unless combined with chemotherapy. Alemtuzumab targets CD52, which is much more highly expressed, and is currently the most effective agent used alone for CLL. Variability in expression of both antigens among these patients might be related to different individual therapeutic responses to mAb therapy. PATIENTS AND METHODS: A total 95 patients diagnosed with CLL and/or SLL were divided into 4 groups: (1) untreated; (2) in complete or partial remission; (3) disease in progression; and (4) diagnosed with SLL. Flow cytometry of peripheral blood cells included gating of the CD5(+)CD19(+) tumor population, within which mean fluorescence intensity of fluorescein isothiocyanate (FITC) conjugated with anti-CD20 or anti-CD52 antibody was measured. The resulting expression of the 2 antigens was deduced from the calibration curve using Quantum FITC particles. RESULTS: Expression of CD20 showed no significant differences among the 4 groups of patients. However, significantly greater expression of surface antigen CD52 was recorded in patient group 2 in complete or partial remission (P < .001). CONCLUSION: The residual population of CLL cells after therapy is characterized by increased surface detection of CD52. Although the exact cause of this phenomenon is unknown, our results provide a basis to consider the potential for CLL consolidation therapy using alemtuzumab.

[Toxoplasmosis of the central nervous systems after allogeneic stem cell transplantation]. / Toxoplazmóza centrálního nervového systému po alogenní transplantaci krvetvorných bunek.

Toxoplasmosis is a rare opportunistic protozoal infection, which may occur in patients after hematopoietic stem cell transplantation. This disease originates almost exclusively from reactivation of latent infection in seropositive recipients. We present a case report of one patient with diagnosis of acute myeloid leukemia undergoing two allogeneic stem cell transplantations at two years interval. The second transplantation was complicated by the development of the toxoplasmic encephalitis in early posttransplant course. The initial neurological symptoms included diplopia caused by the paresis of right side motor branches of the 3rd and 6th cranial nerves due to a compressive lesion in basal ganglia. Patient suddenly deteriorated after an epileptic seizure followed by a loss of consciousness, bilateral ptosis and right side mydriasis. Prolonged sopor and bilateral mydriasis appeared because of the further lesion progression in basal ganglia and compression of the 3rd cranial nerve. After targeted therapy of Toxoplasma gondii the patient's clinical status improved and she regained consciousness. Unfortunately, examination of bone marrow later revealed the relapse of leukemia. We compared risk factors of the latent reactivation of infection in immunocompromised patients with published data. It is of interest that the toxoplasmosis of the brain developed in this patient after the second transplantation.