The effect of white cell depletion of red cells and platelet concentrates on the transmission of cytomegalovirus (CMV) was studied retrospectively in 150 patients treated intensively for acute leukemia or non-Hodgkin's lymphoma. CMV infection was diagnosed on the basis of IgM and IgG antibody responses to CMV late antigen (CMV-LA). Before cytoreductive therapy for their underlying disease, 59 patients were CMV seronegative and 91 were CMV seropositive. None of the 59 CMV-seronegative patients showed persistent seroconversion 2 months after the cytoreductive treatment. The comparison group, consisting of 312 cardiac surgery patients, showed a significantly higher incidence of primary CMV infections: 10 of 86 (11.6%, p = 0.004). Twenty-five percent of the CMV-seronegative patients and controls had transient IgG antibodies to CMV-LA without IgM antibodies, which is indicative of antibodies passively acquired via blood products. These results indicate that white cell-poor blood products carry a very low risk, if any, of CMV transmission. The policy of transfusing white cell-poor blood products provides a useful alternative to the selection of CMV-seronegative donors.

We found an unusual fc gamma receptor IIIa (CD16) phenotype on the natural killer (NK) cells of a 3-year-old boy, who suffered from recurrent viral respiratory tract infections since birth. He also had severe clinical problems after Bacille Calmette-Geerin (BCG) vaccination and following Epstein-Barr virus and Varicella Zoster virus infections. His peripheral blood lymphocytes contained a normal percentage and absolute number of CD3-CD7+ cells, which were positively stained with the CD16 monoclonal antibodies (MoAbs) 3G8 and CLBFcRgran1, but did marginally stain with the CD16 MoAb Lau11c/B73.1. Fc gamma RillIb expression on granulocytes appeared to be normal. NK cell function, analyzed in vitro by direct cytotoxicity on K562 target cells and ADCC-activity on P815 target cells, was normal compared with an age-matched healthy control. Sequence analysis of the Fc gamma RIIIA gene, encoding CD16 on NK cells and macrophages, showed a T to A nucleotide substitution at position 230 on both alleles, predicting a leucine (L) to histidine (H) amino acid change position 48 in the first extracellular lg-like domain of Fc gamma RIIIa, which contains the Leu11c/B73.1 epitope. The combined use of CD16 and CD56 MoAbs labeled with the same fluorescent dye, as often applied in routine immunophenotyping procedures, will leave these homozygotes undiagnosed. The pattern of infections in this patient is in agreement with the postulated function of NK cells in the immunological defense against viruses and other intracellular microorganisms. Further analysis of the NK cell function in vitro and follow-up of the clinical course of Fc gamma RIIIA-48H/H homozygotes is required to ascertain whether this genotype is causally related to an NK cell immunodeficiency.

We studied the effects of herpes virus carrier status on peripheral blood T lymphocyte subsets in 334 healthy individuals. IgG-class antibodies against cytomegalovirus (CMV), Epstein-Barr virus (EBV), herpes simplex virus (HSV), and varicella-zoster virus (VZV) were used as markers for the carrier status of those viruses. CMV carrier status was associated with significant increases in the numbers of some T cell subsets, whereas the carrier status of EBV, HSV, and VZV had no significant effects. The 159 CMV-seropositive individuals had higher numbers of HNK1+ T cells than did the 175 CMV-seronegative individuals [mean (SD), 292 (196)/microL v 164 (89)/microL, respectively], including the CD4+HNK1+ T cells [38 (48)/microL v 9 (13)/microL, respectively] and the CD8+HNK1+ T cells [166 (146)/microL v 73 (54)/microL, respectively]. Morphological and cytochemical studies showed that the expression of HNK1 by the CD4+ and CD8+ T cells was associated with the occurrence of azurophilic cytoplasmatic granules and a loss of nonspecific esterase activity. The numbers of CD4+HNK1+ and CD8+HNK1+ T cells increased proportionally to the levels of the IgG- class CMV antibody titers. We suggest that the increased numbers of CD4+HNK1+ and CD8+HNK1+ granular T cells in CMV carriers reflect the persistent interaction between CMV and the immune system of its hosts.

Lymphocytes, monocytes, granulocytes, and other blood cells can be distinguished on the basis of their forward (FSC) and sideward (SSC) light scatter properties and their expression of CD45 and CD14. A FSC,SSC gate can be set to include >95% of the lymphocytes using a "back gating" procedure on the CD45 + , CD14-cells. However, nonlymphoid cells such as monocytes have light scattering properties similar to lymphocytes. This problem occurs particularly in patient populations where the light scattering properties of lymphocyte subsets have changed (e.g., due to activation) and are similar to those of the monocytes. Thus, immunophenotyping using antibodies specific for other markers than CD45 and CD14 does not allow a direct assessment of the percentage of all lymphocytes positive for those markers. In order to optimize immunophenotyping we have developed an analytic model in which the FSC,SSC dot plot is partitioned into six nonoverlapping light scatter regions. Each light scatter region containsThe identification and quantitative analysis of lymphocyte subsets are an important application of flow cytometry. Lymphocytes can be distinguished from other types of blood cells on the basis of their forward (FSC) and sideward (SSC) light scattering properties (8,lO). Recently, the technique of setting a light scatter gate around the lymphocytes has been optimized by including the expression of CD45 and CD14 in the definition of lymphocytes (5). With this technique, termed a mixture population of different cell types, i.e., lymphocytes, monocytes, granulocytes, and other cells. The proportions of each cell type are known from the CD45,CD14 expression within each light scatter region. Under the assumption of independence of fluorescence and scatter properties conditional on cell type, the expression of markers other than CD45 or CD14 are derived from the cell type composition and the fluorescence properties on the other markers of each light scatter region. The underlying statistical model is a latent class model, and maximum likelihood estimates are computed using the expectation-maximization (EM) algorithm. The application of the model for immunophenotyping of lymphocytes of healthy individuals and cancer patients receiving immunotherapy is shown.

A total of 168 patients (90 adults, 78 children) with immune thrombocytopenia (ITP) and a median follow‐up of 75 months were treated with a sequential regimen of corticosteroids (n = 125), splenectomy (n = 83) and immunosuppressives (n = 25). In 43 patients an observation period of a minimum of 1 month preceded the therapy. It is concluded that: (i) withholding therapy in the expectation of spontaneous recovery is at least in children justified in case of limited bleeding tendency; (ii) corticosteroids should be limited in adults to a maximum of 3 weeks and in children to a maximum of 6 weeks; (iii) if corticosteroids fail, splenectomy remains the therapy of choice, especially in patients aged ≤ 30 years, and should be performed within 6 months after diagnosis; (iv) after failure of the forementioned forms of therapy, there is rarely a beneficial effect of treatment with azathioprine and vincristine; (v) no reaction to any form of therapy can be followed by an acceptable long‐term outcome.