Antibodies to Epstein-Barr virus thymidine kinase: a characteristic marker for the serological detection of nasopharyngeal carcinoma

Patients suffering from nasopharyngeal carcinoma (NPC) generally exhibit elevated serum IgA antibody titres to Epstein-Barr virus (EBV) early antigen (EA) and virus capsid antigen (VCA). This property is frequently used as a diagnostic aid. Preliminary experiments suggested that an ELISA for IgA antibodies against the EBV-encoded thymidine kinase (TK) could form the basis of a more reliable diagnostic test. Here, we describe the construction of a recombinant baculovirus that expresses the EBV TK and present a full analysis of its use in serological surveys of NPC patients. Baculovirus-derived TK was used to develop a simple ELISA for serum IgA against this antigen. ELISA reactivity was strongly associated with NPC compared with an EBV-positive, normal control population. Comparison with the existing IgA-VCA and EA assays showed that the TK ELISA had higher sensitivity whilst the specificity was similar or higher. We conclude that the TK ELISA presents a strong predictor of NPC and, in its refined form, has improved pickup rates. In addition, results from patients with chronic nasopharyngitis (CNP) suggest that individuals with both symptoms of CNP and an elevated TK ELISA value may be at increased risk for the development of head-and-neck cancer.

Nasopharyngeal antibodies to pneumococcal pneumolysin in children with acute otitis media

Pneumolysin, an intracellular protein toxin of all clinically relevant pneumococcal serotypes, is released in vivo during the autolysis of pneumococci and is believed to pave the way for intact pneumococci to invade and cause disease. Therefore, antibodies to pneumolysin should prevent its destructive function. We measured antibodies to pneumococcal pneumolysin in acute- and convalescent-phase nasopharyngeal aspirate samples of 120 children (median age, 2.5 years) with acute otitis media by enzyme immunoassay. Nasopharyngeal immunoglobulin M (IgM) and IgG class antibodies to pneumolysin were rarely detectable, whereas IgA class antibody was detected often, occurred independently of serum IgA antibody in serum, and correlated with the presence of the secretory component in pneumococcal antibody, indicating local production of IgA antibodies. Nasopharyngeal IgA antibody to pneumolysin was detected in 93% of the children already in the acute phase of otitis. Twenty percent of the children developed at least a threefold rise in the pneumolysin-specific IgA antibody concentration by the convalescent phase of otitis, with the youngest at 6 months of age, regardless of the pneumococcal findings in the nasopharynx or middle ear fluid. We suggest that nasopharyngeal IgA antibody to pneumolysin can be produced early in life by pneumococcal colonization.

[Changes in specific and nonspecific immunity factors in saliva and serum of patients with different clinical variants of meningococcal infection]

Local and humoral immunity factors have been studied in 152 patients with different forms of meningococcal infection. The peculiar pattern of the time course of changes in these factors, depending on the clinical form of the disease, has been revealed. In the generalized form of infection changes in the immunological characteristics of the saliva and blood serum (lysozyme, secretory immunoglobulin, immunoglobulins of the main classes and specific antimeningococcal antibodies) have been shown to be more essential than in the localized form.

[Serologic studies of patients with meningococcal nasopharyngitis]

The results of the serological examination of 156 patients with bacteriologically confirmed meningococcal nasopharyngitis are presented. For control 221 patients with acute respiratory diseases and 345 healthy persons from groups having no registered cases of meningococcal infection were examined. The passive hemagglutination test with serogroup A and C polysaccharides revealed the presence of antibody titers between 1:20 and 1:640 in 67.3% of nasopharyngitis patients and antibody titers not exceeding 1:40 in 11.3-11.6% of persons in the control groups. The time course of antibody formation in nasopharyngitis was similar to that in generalized forms, but response was less pronounced: the maximum response was observed on days 5-10, and the decrease of the antibody level by day 20. In 47 foci of meningococcal infection the etiology of the disease was serologically confirmed on the first day of an epidemiologist's visit to the focus in 62.2% of 162 nasopharyngitis patients and in 36% of patients with acute respiratory diseases.

[Level of rosette-forming cells in patients with meningococcal infections]

In patients with the generalized form of meningococcal infection a disease in the level of T-lymphocytes was revealed at early stages of the disease. This decrease correlated with the gravity of the process. On week 2 of the disease an increase in the level of B-lymphocytes was observed, which probably occurred due to the appearance of the clone of antibody-producing precursor cells. The content of specific rosette-forming cells, carrying receptors to the cell-wall antigens of group A and C meningococci, increased in the blood of patients on week 1 of the disease, which did not correlate with the increase of the titer of specific antibodies on weeks 2-3.