Two homosexual men with the acquired immunodeficiency syndrome (AIDS) who developed a multicentric variant of angiofollicular lymph node hyperplasia (AFLNH) (Castleman's disease) and Kaposi's sarcoma are reported. Both had diffuse adenopathy, splenomegaly, and a systemic inflammatory state. Both had an absolute increase in Leu 1+ lymphocytes, which was associated with markedly decreased Leu 3+ lymphocytes, markedly increased Leu-2+ lymphocytes, and a very low Leu 3/2 ratio. The lymphocytes of both patients had a normal blastogenic response to PHA. The lymphocytes of patient 1 had a poor response to autologous or allogenic cells in the mixed lymphocyte culture reaction. AFLNH represents another lymphoreticular complication of AIDS. Given the interrelationships between AFLNH, the development of Kaposi's sarcoma, and the aggressive clinical course seen in our two patients and those in the literature, the aggressive use of lymph node biopsy may be an important prognostic tool for the patient with the acquired immunodeficiency syndrome.

Mutations in the Wiskott-Aldrich syndrome protein (WASP) have been hypothesized to cause defective actin cytoskeletal function. This resultant dysfunction of the actin cytoskeleton has been implicated in the pathogenesis of Wiskott-Aldrich syndrome (WAS). In contrast, it was found that stimulated actin polymerization is kinetically normal in the hematopoietic lineages affected in WAS. It was also found that the actin cytoskeleton in WAS platelets is capable of producing the hallmark cytoarchitectural features associated with activation. Further analysis revealed accelerated cell death in WAS lymphocytes as evidenced by increased caspase-3 activity. This increased activity resulted in accelerated apoptosis of these cells. CD95 expression was also increased in these cells, suggesting an up-regulation in the FAS pathway in WAS lymphocytes. Additionally, inhibition of actin polymerization in lymphocytes using cytochalasin B did not accelerate apoptosis in these cells. This suggests that the accelerated apoptosis observed in WAS lymphocytes was not secondary to an underlying defect in actin polymerization caused by mutation of the WAS gene. These data indicate that WASP does not play a universal role in signaling actin polymerization, but does play a role in delaying cell death. Therefore, the principal consequence of mutations in theWAS gene is to accelerate lymphocyte apoptosis, potentially through up-regulation of the FAS-mediated cell death pathway. This accelerated apoptosis may ultimately give rise to the clinical manifestations observed in WAS.