Serum IgA and secretory IgA (SIgA) were determined in 1,000 apparently healthy subjects; 274 were tonsillectomized. Four groups were identified in this study: (1) 0.3% of subjects had no serum IgA and SIgA; (2) 1.6% of subjects showed partial serum and SIgA deficiency; (3) 27.4% of individuals were tonsillectomized and had partial serum IgA deficiency but normal SIgA, and (4) 71.4% were normal, both with respect to serum IgA and SIgA. These results stress the relatively high incidence of IgA deficiency in the normal population and confirm the role of the tonsils in maintaining serum IgA levels.

The clinical and immunological responses to typhoid vaccination with parenteral (TAB) and oral (Ty2la) vaccines in two groups of 30 adult male subjects were studied. Parameters monitored included specific anti-Salmonella typhi cell-mediated immunity and total and specific antilipopolysaccharide fecal immunoglobulin A (IgA) titers in Ty2la-vaccinated subjects. Peripheral blood lymphocyte antibacterial activity was significantly increased only in Ty2la-vaccinated subjects. Serum arming activity and results of human F(ab')2 anti-IgG and -IgA inhibition tests suggest antibody-dependent cellular cytotoxicity mediated by IgA in those vaccinated with Ty2la. Interestingly enough, the cells of TAB-vaccinated subjects were able to mediate IgG-dependent cellular cytotoxicity, as was observable from the results of blocking experiments. Moreover, total and specific antilipopolysaccharide fecal IgA levels were observed to be significantly increased with Ty2la, up to 8 months post-vaccination schedule. An early-onset, transitory increase in serum IgM rheumatoid factor was also found, exclusively in subjects treated with TAB, and was no longer detectable on day 240. Ty2la was well tolerated and free of side effects, whereas 65% of subjects administered TAB reported fever, headache, malaise, and local tenderness at the injection site. Our data show that the two typhoid vaccines induce different cell-mediated specific immune responses. The role of these responses in protection against Salmonella infection, however, requires further investigation.

Oxidative metabolic burst of activated human polymorphonuclear leukocytes (PMN) is most commonly investigated in clinical practice by evaluating nitroblue tetrazolium (NBT) reduction at the single cell level. Reduced NBT precipitates where the redox reaction has taken place and can be visualized as PMN-associated dark blue granules of formazan in light microscopy. Although widely used and not technically demanding, this method remains subjective and labor intensive, especially when large numbers of samples need to be investigated. We developed a new flow cytometry technique in which PMN membrane was rendered fluorescent by a short incubation with fluorescein-conjugated Concanavalin A. PMN were then incubated with NBT and increasing doses of a suitable stimulus, such as phorbol myristate acetate (PMA). Formazan has a distinct peak of absorption at 520 nm that represents the peak of emission of fluorescein. As a consequence, formazan quenches the PMNassociated fluorescence. Data show that a dose-dependent reduction of fluorescence can be obtained using graded amounts of PMA in normal PMN cultures. PMN-associated fluorescence remains unchanged in control patients with chronic granulomatous (CGD) disease, a disorder characterized by a selective impairment of PMN oxidative metabolism. Electronic cell size increases upon PMA incubation in normal PMN, irrespective of the presence of NBT. Conversely, forward light scatter intensity decreases in the presence, but not in the absence, of NBT indicating that the phenomenon is due to the capacity of formazan to absorb/ scatter the incident light. The present method for easily detecting NBT reducing activity at single cell level by flow cytometry makes use of commonly available, inexpensive reagents and standard instrumentation. It could become a useful test for clinical purposes.

SUMMARYSerum antibodies to the capsular polysaccharides A and C (PSA and PSC) of N. meningitidis in healthy adults before and after vaccination with the sole polysaccharides were analysed by isoeleciric focusing (lEF). Before vaccination, 49'X. and 28% had naturally acquired antibodies against PSA and PSC, respectively, whereas 18 days after vaccine administration 84% and 91%, respectively, showed a deteclable speclrotypic pattern. Oligoclonaliiy appeared to be the main feature of naturally acquired and vaccine-induced antibodies lor both polysaccharides. In all subjects the anii-PSA response, showing dominant bands at the same pH position, was more homogeneous than anti-PSC one. Most subjects with naturally acquired antibodies (25 out of 38 for PSA and 20 out of 22 for PSC) showed a spectrotypic pattern after vaccination, similar to that observed before vaccination (any differences were just related to band intensity), suggesting that PSA and PSC are able to recruil the same B cell clones previously primed with a T-dependent form of the antigen, i.e. the whole bacterium. However, in one-third of subjects with naturally acquired anli-PSA antibodies, the appearance of new alkaline bands after vaccination was observed. Furthermore, in subjects with absence of deleclablc natural antibodies, the vaccine-induced antibody response started in correspondence of alkaline pH area.s, subsequently extending lo neutral and acidic areas. Therefore, il may be hypothesized that alkaline antibody-secreting Bcell clones are the first tobe recruited. The final .speclrotype in these subjects was similar to that observed in subjeets wiih naturally acquired antibodies. This observation, together with the above reported data, allow us to conclude that natural (T-dcpendent palhway) and vaccine (T-independent pathway) immunization induce ihe expression of the same antibody repertoire, for both meningococcal PSA and PSC.

SUMMARY The locomotor function of polymorphonuclear cells (cellular chemotaxis) and serum chemotactic activity (humoral chemotaxis) were studied in 51 patients with Crohn's disease using a method of migration under agarose gel. To study cellular chemotaxis patient's polymorphonuclear cells were challenged against normal Zymosan activated serum and humoral chemotaxis was evaluated testing the patient's Zymosan activated serum against normal polymorphonuclear cells.