SummaryA critical event during programmed cell death (PCD) appears to be the acquisition of plasma membrane (PM) changes that allows phagocytes to recognize and engulf these cells before they rupture. The majority of PCD seen in higher organisms exhibits strikingly similar morphological features, and this form of PCD has been termed apoptosis. The nature of the PM changes that occur on apoptotic cells remains poorly defined. In this study, we have used a phosphatidylserine (PS)-binding protein (annexin V) as a specific probe to detect redistribution of this phospholipid, which is normally confined to the inner PM leaflet, during apoptosis. Here we show that PS externalization is an early and widespread event during apoptosis of a variety of murine and human cell types, regardless of the initiating stimulus, and precedes several other events normally associated with this mode of cell death. We also report that, under conditions in which the morphological features ofapoptosis were prevented (macromolecular synthesis inhibition, overexpression of Bcl-2 or Abl), the appearance of PS on the external leaflet of the PM was similarly prevented. These data are compatible with the notion that activation of an inside-outside PS translocase is an early and widespread event during apoptosis.

Two classes of low-affinity receptors for the Fc region of immunoglobulin G (IgG) (Fc␥R) are constitutively expressed on resting human neutrophils. These receptors, termed Fc␥RIIa (CD32) and Fc␥RIIIb (CD16), display biallelic polymorphisms which have functional consequences with respect to binding and/or ingestion of targets opsonized by human IgG subclass antibodies. The H131-R131 polymorphism of CD32 influences binding of human IgG2 and, to a lesser extent, human IgG3 to neutrophils. The neutrophil antigen (NA1-NA2) polymorphism of CD16 influences the efficiency of phagocytosis of bacteria opsonized by human IgG1 and IgG3. These polymorphisms may influence host susceptibility to certain infectious and/or autoimmune diseases, prompting interest in the development of facile methods for determination of CD32 and CD16 genotype in various clinical settings. We previously reported that genomic DNA from saliva is a suitable alternative to DNA from blood in PCR-based analyses of CD32 and CD16 polymorphisms. In the present study, we utilized for the first time this salivary DNA-based methodology to define CD32 and CD16 genotypes in 271 Caucasian and 118 African-American subjects and to investigate possible linkage disequilibrium between certain CD32 and CD16 genotypes in these two ethnic groups. H131 and R131 gene frequencies were 0.45 and 0.55, respectively, among Caucasians and 0.59 among African-Americans. NA1 and NA2 gene frequencies were 0.38 and 0.62 among Caucasians and 0.39 and 0.61 among African-Americans. Since Fc␥RIIa and Fc␥RIIIb synergize in triggering neutrophils, we also assessed the frequency of different CD32 and CD16 genotype combinations in these two groups. In both groups, the R/R131-NA2/NA2 genotype combination was more common than the H/H131-NA1/NA1 combination (threefold for Caucasians versus sevenfold for AfricanAmericans). Whether individuals with the combined R/R131-NA2/NA2 genotype are at greater risk for development of infectious and/or autoimmune diseases requires further investigation, which can be conveniently performed using DNA from saliva rather than blood.

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SUMMARYThe immature neonatal immune system is thought to result in increased risk of infection. Receptors for the Fc moiety of IgG (Fc R) are important in antibody-mediated clearance of microbes by granulocytes and monocytes/macrophages. As an approach to understanding their role in neonatal life, we have compared the constitutive expression of the three Fc receptors-Fc RI (CD64), Fc RII (CD32) and Fc RIII (CD16)-by neonatal and adult blood monocytes and granulocytes using quantitative immunofluorescence by flow cytometry. Our results confirm that there is a small subpopulation of Fc RII-positive monocytes in adult blood, and furthermore show that this is absent or at a low percentage in cord blood samples. However, the main population of cord blood monocytes expresses low, but significantly higher levels of Fc RIII than adult monocytes. No differences were seen in the quantitative expression of Fc RI and Fc RII. Neonatal granulocytes expressed significantly higher levels of both Fc RI and Fc RII but significantly lower levels of Fc RIII. The data are discussed in terms of the possible role of cytokines and susceptibility to infection.

Heat shock proteins (hsps) can induce anti-cancer immune responses by targeting associated tumour antigens to the immune system. Hsps are not merely carriers of antigen but can also induce maturation of dendritic cells (DCs), resulting in a more efficient antigen presentation. However, improvement of hsp-based vaccines is still desirable if one is to realize their full therapeutic potential. Since the immune system consists of different elements functioning together in a highly integrated way, a combination therapy utilizing important immunomodulators together with hsp-based vaccination may improve therapeutic response. Hyperthermia has been shown to have important stimulatory effects on several cellular and organismal endpoints related to the immune system. This review highlights advantages and disadvantages of various ways of using stress proteins in cancer immunotherapy. It also overviews the interaction of hyperthermia with heat shock protein therapy and the related effects on the host's immune response.