Increased leukocyte aggregation induced by gamma-globulin: A clue to the presence of pseudoleukopenia

Background: Previous articles have reported the appearance of leukopenia af ter the administration of high-dose intravenous gamma-globulins. Methods: A simple slide test was used to reveal the state of leukocyte aggregation (L A) in the peripheral blood as well as the absolute number of leukocytes in the slides. Results: A significant (P < 0.00001) increment was noted in the state of LA, from 9 +/- 6% before to 25 +/- 11% after gamma-globulin admin istration. This was accompanied by a significant (P < 0.0004) reduction in the number of white blood cells in the peripheral blood (from 8433 +/- 3905 to 6550 +/- 3252 cells/mm(3)) but no significant change in the absolute nu mber of the cells as determined by the leukocyte count per high power field in the peripheral slides. Conclusions: We raise the possibility that the l eukopenia reported in some patients after the intravenous administration of high dose gamma-globulin is explained in part by the agglutination effect of the drug.