Respiratory papillomas, caused by human papillomaviruses, are benign tumors that recur following removal. We evaluated immune function and major histocompatibility complex (MHC) phenotype and expression in these patients. MHC-independent immune function appeared normal. The frequency of peripheral blood MHC class II phenotypes was highly enriched for DQ3 and DR11, one split of DR5. Class I MHC antigen expression on papilloma tissue was markedly reduced. Together, these phenomena may facilitate papillomavirus evasion of the cellular immune response.

We report the identification and purification of an endogenous carbohydratecontaining receptor of pallidin, the cell surface lectin implicated in mediating cell-cell adhesion in the cellular slime mold Polysphondylium pallidum . The receptor is identified in an aqueous extract of crude P. pallidurn membranes as a potent inhibitor of the hemagglutination activity of pallidin . The inhibitor is purified to apparent homogeneity by affinity precipitation with pallidin followed by fractionation of the solubilized precipitate on Sepharose 4B . The hemagglutination inhibitor (HAI) is metabolically radiolabeled, indicating that it is a biosynthetic product of the amoebae and not an ingested food substance. The HAI is released into the extracellular medium by living, differentiated amoebae. This release is markedly facilitated by the addition of D-galactose, a specific saccharide that binds to pallidin . Hence, the HAI appears to have an in situ association with pallidin at the cell surface. Exogenously added HAI promotes the agglutination of differentiated amoebae in a gyrated suspension at very low concentrations . The results are consistent with a model of cell-cell adhesion in which the HAI is a multivalent, extracellular aggregation factor that is recognized by pallidin molecules on adjacent cells. The HAI would then be analogous to the aggregation factors identified in marine sponges.Aggregation-competent amoebae of the cellular slime mold Polysphondylium pallidum contain a soluble galactose-binding hemagglutinin (1) . This lectin, pallidin, consists of a family of three closely related isolectins, each consisting of different combinations of three subunits of 25-27 kdaltons (2, 3). Considerable evidence indicates that this lectin may be involved in intercellular adhesion ofthe slime mold amoebae : (a) the lectin is present in an active carbohydrate-binding form on the cell surface of differentiated, mutually adhesive amoebae and in a lesser amount on vegetative amoebae (1, 4); (b) high-affinity receptor sites for pallidin are present on the cell surface of differentiated amoebae, as detected by agglutination studies, binding measurements, and cytochemical means (1, 4, 5); (c) high concentrations (>50 mM) of specific saccharide inhibitors of pallidin (lactose or D-galactose) selectively block the cohesiveness of amoebae in swirled suspensions (1) ; (d) the specific lectin antagonists, asialofetuin and immune F'ab, also block the intercellular adhesion ofgyrated amoebae when the assays are carried out in hypertonic media or in the presence of antimetabolites (6, 7). These results suggest that the complementary interaction between pallidin and its receptor on adjoining cells is involved in the mediation ofcell-cell adhesion. Recent genetic experiments have established that the principal

In humans with advanced human immunodeficiency virus (HIV) infection, an interferon-alpha (IFN-alpha) response by a specialized blood mononuclear cell to herpes simplex virus (HSV) in vitro is associated with resistance to opportunistic infections. A cell type of unknown lineage, designated the natural IFN-producing cell (NIPC), has been identified preliminarily as the source of these IFNs and may have a role in other host defense functions. Earlier studies suggested the existence of analogous HSV-responsive cell populations in mice. The role specifically of IFN-alpha in the murine system, however, has not been characterized. Using IFN bioassay and neutralization with antisera against Type I IFNs and IFN-beta, we have defined the types and sources of IFNs produced by mice in response to in vivo and in vitro challenge with UV-inactivated HSV. After intraperitoneal inoculation with HSV, BALB/c and C57Bl/6 strains produced characteristically different levels of serum IFNs that appeared principally to be IFN-alpha. The response of mononuclear cells from these mice differed from that of the intact mouse. Isolated cells from bone marrow and spleen released detectable IFNs much later than did whole animals, and the IFNs produced by marrow, spleen, and peritoneal cells were usually neutralized by the anti-IFN-beta. Only bone marrow cells produced detectable amounts of IFN-alpha. Both intact mice and their cells became refractory to restimulation with similar kinetics.