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Infection of monocytes with human immunodeficiency virus type 1Ba-L (HIV-1Ba-L ) is significantly inhibited by treatment with the serine protease inhibitor, secretory leukocyte protease inhibitor (SLPI). SLPI does not appear to act on virus directly, but rather the inhibitory activity is most likely due to interaction with the host cell. The current study was initiated to investigate how SLPI interacts with monocytes to inhibit infection. SLPI was found to bind to monocytes with high affinity to a single class of receptor sites (∼7,000 receptors per monocyte, KD = 3.6 nmol/L). The putative SLPI receptor was identified as a surface protein with a molecular weight of 55 ± 5 kD. A well-characterized function of SLPI is inhibition of neutrophil elastase and cathepsin G. However, two SLPI mutants (or muteins) that contain single amino acid substitutions and exhibit greatly reduced protease inhibitory activity still bound to monocytes and retained anti–HIV-1 activity. SLPI consists of two domains, of which the C-terminal domain contains the protease inhibiting region. However, when tested independently, neither domain had potent anti–HIV-1 activity. SLPI binding neither prevented virus binding to monocytes nor attenuated the infectivity of any virus progeny that escaped inhibition by SLPI. A polymerase chain reaction (PCR)-based assay for newly generated viral DNA demonstrated that SLPI blocks at or before viral DNA synthesis. Therefore, it most likely inhibits a step of viral infection that occurs after virus binding but before reverse transcription. Taken together, the unique antiviral activity of SLPI, which may be independent of its previously characterized antiprotease activity, appears to reside in disruption of the viral infection process soon after virus binding.

Despite the presence of HIV-1 in the oral cavity, transmission of the virus through saliva has not been proven. Consistent with these observations, we recently identified an endogenous 12 kD protein, secretory leukocyte protease inhibitor (SLPI), in saliva which blocks HIV-1 infection in vitro. Whereas other salivary proteins tested were inactive, purified native or recombinant SLPI inhibited HIV-1 infection of human monocytes at 100 ng ml-1. Levels of SLPI quantitated by ELISA in saliva from control and HIV-1 infected individuals exceeded this level, consistent with in vivo antiviral activity. As in saliva, levels of SLPI mRNA determined by Northern hybridization, and protein as assessed by immunohistochemistry in the salivary glands of control and infected populations were comparable. In contrast to adults, oral transmission occurs in infants, possibly due to their lack of fully developed salivary glands. To determine whether the inadequate antiviral protection might be compensated for by maternal sources, we evaluated breast milk samples obtained 6 months postpartum. Levels of SLPI were significantly lower than in saliva and not sufficient to provide antiviral protection in contrast to colostrum samples in which SLPI levels were equivalent to those in saliva and able to inhibit HIV-1 infection when tested in vitro. These data suggest that breast milk may provide transient antiviral activity in the newborn, but that this maternal source of SLPI is of insufficient duration to maintain protection against mucosal transmission of the virus over time. The high functional levels of SLPI in saliva and the low levels in mature breast milk correlate with negligible rates of HIV-1 transmission by saliva and higher rates by breast feeding.

The function of the lipophosphoglycan of Leishmania donovani parasites was investigated in human peripheral monocytes. In contrast to wild-type L. donovani which grow in monocytes, incubation of monocytes with two variant lines of L. donovani, defective in lipophosphoglycan expression, resulted in the entry of the variant cells into the monocytes and their subsequent destruction. Passive transfer of lipophosphoglycan to the variant cells led to prolonged survival in monocytes. These results indicate that lipophosphoglycan is required by the parasite for intracellular survival. To investigate one possible protective role of the glycoconjugate, preincubation of monocytes with a suspension of lipophosphoglycan and subsequent treatment of the cells with PMA or opsonized zymosan resulted in an attenuation of the oxidative burst; the attenuation effect was concentration dependent on the glycoconjugate and independent of preincubation time. Moreover, hydrophobic beads, coated with lipophosphoglycan, were phagocytized by monocytes and found to inhibit oxygen consumption in monocytes activated with PMA. These results suggest a possible relationship between the absence of lipophosphoglycan in the variant parasites and their inability to survive within monocytes. Although the precise molecular basis remains to be elucidated, the ability of lipophosphoglycan to impair the microbial oxidative response may be a contributing factor in its requirement for intracellular survival.

Infection of monocytes with human immunodeficiency virus type 1(Ba-L) (HIV-1(Ba-L)) is significantly inhibited by treatment with the serine protease inhibitor, secretory leukocyte protease inhibitor (SLPI). SLPI does not appear to act on virus directly, but rather the inhibitory activity is most likely due to interaction with the host cell. The current study was initiated to investigate how SLPI interacts with monocytes to inhibit infection. SLPI was found to bind to monocytes with high affinity to a single class of receptor sites (approximately 7,000 receptors per monocyte, K(D) = 3.6 nmol/L). The putative SLPI receptor was identified as a surface protein with a molecular weight of 55 +/- 5 kD. A well-characterized function of SLPI is inhibition of neutrophil elastase and cathepsin G. However, two SLPI mutants (or muteins) that contain single amino acid substitutions and exhibit greatly reduced protease inhibitory activity still bound to monocytes and retained anti-HIV-1 activity. SLPI consists of two domains, of which the C-terminal domain contains the protease inhibiting region. However, when tested independently, neither domain had potent anti-HIV-1 activity. SLPI binding neither prevented virus binding to monocytes nor attenuated the infectivity of any virus progeny that escaped inhibition by SLPI. A polymerase chain reaction (PCR)-based assay for newly generated viral DNA demonstrated that SLPI blocks at or before viral DNA synthesis. Therefore, it most likely inhibits a step of viral infection that occurs after virus binding but before reverse transcription. Taken together, the unique antiviral activity of SLPI, which may be independent of its previously characterized antiprotease activity, appears to reside in disruption of the viral infection process soon after virus binding.

Despite the presence of HIV-1 in the oral cavity, transmission of the virus through saliva has not been proven. Consistent with these observations, we recently identified an endogenous 12 kD protein, secretory leukocyte protease inhibitor (SLPI), in saliva which blocks HIV-1 infection in vitro. Whereas other salivary proteins tested were inactive, purified native or recombinant SLPI inhibited HIV-1 infection of human monocytes at 100 ng ml-1. Levels of SLPI quantitated by ELISA in saliva from control and HIV-1 infected individuals exceeded this level, consistent with in vivo antiviral activity. As in saliva, levels of SLPI mRNA determined by Northern hybridization, and protein as assessed by immunohistochemistry in the salivary glands of control and infected populations were comparable. In contrast to adults, oral transmission occurs in infants, possibly due to their lack of fully developed salivary glands. To determine whether the inadequate antiviral protection might be compensated for by maternal sources, we evaluated breast milk samples obtained 6 months postpartum. Levels of SLPI were significantly lower than in saliva and not sufficient to provide antiviral protection in contrast to colostrum samples in which SLPI levels were equivalent to those in saliva and able to inhibit HIV-1 infection when tested in vitro. These data suggest that breast milk may provide transient antiviral activity in the newborn, but that this maternal source of SLPI is of insufficient duration to maintain protection against mucosal transmission of the virus over time. The high functional levels of SLPI in saliva and the low levels in mature breast milk correlate with negligible rates of HIV-1 transmission by saliva and higher rates by breast feeding.

The rarity of oral transmission of human immunodeficiency virus (HIV)-1 by saliva suggests the absence of HIV-1 in the oral cavity and/or the presence of viral inhibitory molecules. We analyzed salivary gland tissues from 55 individuals with acquired immune deficiency syndrome (AIDS) for the presence of HIV-1 by in situ hybridization and detected the virus in more than 30% of these salivary glands. These data, together with previous demonstrations of HIV-1 in oral secretions, implicate a key role for an anti-viral molecule(s) in suppressing transmission. Thus, we focused on the characterization and localization of the endogenous antiviral molecule secretory leukocyte protease inhibitor (SLPI), which inhibits HIV-1 infection in vitro. Expression of SLPI transcripts was evident in submandibular, parotid, and minor salivary glands from both HIV-1-infected and seronegative subjects. Gene expression was reflected by similar levels of SLPI protein by immunohistochemical analysis in the tissues and by enzyme-linked immunosorbent assay in the saliva. However, although SLPI accumulated in acinar cells or ductal epithelium, HIV-1 transcripts did not, and these viral transcripts were identified only in mononuclear cells within the salivary gland stroma. By in situ hybridization, we found no evidence of productive HIV-1 infection of salivary gland epithelium. Thus, HIV-1 was frequently identified in salivary gland tissue, but the virus was found in interstitial mononuclear cells only and did not co-localize with SLPI. Once within the oral cavity, HIV-1 exposure to antiviral levels of SLPI may impede infection of additional target cells, contributing to the virtual absence of oral transmission of HIV-1 by saliva. These studies emphasize the importance of innate, endogenous inhibitors of HIV-1, particularly SLPI, as effective inhibitors of HIV-1 transmission.

Infection of adherent primary monocytes with HIV-1Ba-L is significantly suppressed in the presence of human saliva. By reverse transcriptase (RT) levels, saliva, although present for only 1 h during monocyte viral exposure, inhibited HIV-1 infectivity for 3 wk after infection, whereas human plasma and synovial fluid failed to inhibit HIV-1 infectivity. Antiviral activity was identified in the saliva soluble fraction, and to determine the factor(s) responsible, individual saliva proteins were examined. Of those proteins examined, only secretory leukocyte protease inhibitor (SLPI) was found to possess anti-HIV-1 activity at physiological concentrations. SLPI anti-HIV-1 activity was dose dependent, with maximal inhibition at 1-10 micrograms/ml (> 90% inhibition of RT activity). SLPI also partially inhibited HIV-1IIIB infection in proliferating human T cells. SLPI appears to target a host cell-associated molecule, since no interaction with viral proteins could be demonstrated. However, SLPI anti-HIV-1 activity was not due to direct interaction with or downregulation of the CD4 antigen. Partial depletion of SLPI in whole saliva resulted in decreased anti-HIV-1 activity of saliva. These data indicate that SLPI has antiretroviral activity and may contribute to the important antiviral activity of saliva associated with the infrequent oral transmission of HIV-1.

The ability of surfactant protein A (SP-A) to aggregate and opsonize type a and b Hemophilus influenzae was investigated. Type a, but not type b, was aggregated by SP-A. Aggregation was maximal at 24 micrograms SP-A/ml and was Ca(2+)-dependent. Aggregation of type a was inhibited by D-glucosyl-BSA but not by high concentrations of monosaccharides (D-mannose, D-galactose, D-glucose, or L-fucose) or by sialic acid, purified type a capsular polysaccharide, or type IV collagen. In Western blots, 125I-labeled SP-A bound to the major outer membrane protein (putatively P2) of type a hemophilus by a Ca(2+)-dependent mechanism. This binding was competitively inhibited by excess unlabeled SP-A. 125I-labeled SP-A also bound to the major membrane protein of type b, but at less than 5% of the level observed for type a. SP-A did not bind to lipooligosaccharides of either type a or type b. SP-A increased association of type a, but not type b, hemophilus with alveolar macrophages. After opsonization with SP-A, type a hemophilus were killed by alveolar macrophages, as indicated by bactericidal assays and the release of soluble, radiolabeled products from leukocytes. It is concluded that SP-A aggregated and opsonized type a hemophilus, but not type b, possibly because SP-A bound to the P2 outer membrane protein of type a to a greater extent.

This study evaluated the diagnostic accuracy of fine needle aspiration biopsy (FNAB) of follicular lymphoma (FL). Fourteen aspirates of lymph nodes in which follow-up surgical biopsy revealed FL were studied. Two aspirates were deemed unsatisfactory because of a paucity of cells. The remaining 12 cases received the following diagnoses: 4 positive for malignant lymphoma, 4 highly suspicious for malignant lymphoma and 4 false negatives. FNAB of FL can show a monomorphic or polymorphic cell population. The aspirates with a positive or suspicious diagnosis showed monomorphic cell populations. False-negative diagnoses were attributable to misleading sampling or preparation methods in most cases. We conclude that FNAB of FL is less accurate than FNAB of non-Hodgkin's malignant lymphoma (NHL) in general, but the accuracy rate is similar to that of FNAB of all low-grade NHL. The value of current approaches to the diagnosis of suspected lymphoma by FNAB is emphasized.

A 25-year-old woman, multigravida, presented with a dark ulcerated tumor of the clitoris. Histologic examination demonstrated an angiokeratoma, a benign telangiectatic vascular tumor. To our knowledge, this is the first report of angiokeratoma of the clitoris and only the fifth describing vascular tumor of this organ. The clinical differential diagnosis of angiokeratoma and of clitoral tumors includes malignant neoplasms such as melanoma. Biopsy with histologic examination is, therefore, recommended to ensure appropriate treatment of these unusual tumors.

Fine-needle aspiration of an adrenal mass was performed to rule out metastatic disease in a patient with a bronchogenic carcinoma. The aspiration was misinterpreted as metastatic small cell anaplastic carcinoma. Review of the aspirate by the authors revealed the atypical small cells to be aggregates of bare nuclei of benign adrenocortical cells. Interpretation of these bare nuclei in isolation and unfamiliarity with the aspiration cytology of the adrenal gland led to the initial misdiagnosis.

The function of the lipophosphoglycan of Leishmania donovani parasites was investigated in human peripheral monocytes. In contrast to wild-type L. donovani which grow in monocytes, incubation of monocytes with two variant lines of L. donovani, defective in lipophosphoglycan expression, resulted in the entry of the variant cells into the monocytes and their subsequent destruction. Passive transfer of lipophosphoglycan to the variant cells led to prolonged survival in monocytes. These results indicate that lipophosphoglycan is required by the parasite for intracellular survival. To investigate one possible protective role of the glycoconjugate, preincubation of monocytes with a suspension of lipophosphoglycan and subsequent treatment of the cells with PMA or opsonized zymosan resulted in an attenuation of the oxidative burst; the attenuation effect was concentration dependent on the glycoconjugate and independent of preincubation time. Moreover, hydrophobic beads, coated with lipophosphoglycan, were phagocytized by monocytes and found to inhibit oxygen consumption in monocytes activated with PMA. These results suggest a possible relationship between the absence of lipophosphoglycan in the variant parasites and their inability to survive within monocytes. Although the precise molecular basis remains to be elucidated, the ability of lipophosphoglycan to impair the microbial oxidative response may be a contributing factor in its requirement for intracellular survival.