Immunological studies of an artificial antigen with specificity of a common polysaccharide antigen of Pseudomonas aeruginosa

Abstract Synthetic d -rhamnan, with the structure of Pseudomonas aeruginosa common polysaccharide antigen (CPA), was conjugated with BSA. The artificial antigen obtained, and the natural antigens, lipopolysaccharides (LPS) of P. aeruginosa and Pseudomonas cerasi with rhamnan chains of the same structure, were studied by ELISA with rabbit antibodies to the d -rhamnan-BSA conjugate and to the P. cerasi O-antigen. Immunological relations between the LPS of P. aeruginosa and P. cerasi determined by CPA as well as between these LPS and d -rhamnan-BSA were revealed by ELISA. O-antiserum to P. cerasi possesses protective activity in the mouse passive protection test when mice are challenged with some P. aeruginosa strains; the antiserum to the d -rhamnan-BSA does not possess protective activity in mice.     

Additional studies of histoplasmin formation

Summary Culture filtrates of 20 strains ofHistoplasma capsulatum were studied to determine the effect of certain growth conditions on histoplasmin formation. The presence of histoplasmin was denoted by an antigenic titer of 1:4 or higher with the complement fixation test.The data indicated that, in addition to verifying that the strain used affected histoplasmin formation, the morphological condition of the inoculum was extremely important. It was found that most strains which converted readily to the yeast phase at 37° C produced histoplasmin poorly. Tests with different volumes of media also showed that 500 ml volumes of culture media produced histoplasmin with higher titers than 3 liter volumes when cultured at 25° C for six months.Some additional histoplasmin could be liberated by sonification of the mycelial pad from culture filtrates which contained histoplasmin. A few strains produced high titer histoplasmin by the shake method if incubated for three months, but they had low titers after only six weeks.Complement fixation tests with sera from proven cases of histoplasmosis indicated that histoplasmin from a single strain ofH. capsulatum can give identical results with those obtained with histoplasmin from a pool ofH. capsulatum strains if H and M antigen components are present.     

Two-dimensional immunoelectrophoresis of histoplasmin and a purified polysaccharide-protein antigen ofHistoplasma capsulatum

Crude histoplasmin and a polysaccharide-protein complex (PPC-histo) antigens obtained from culture filtrates ofHistoplasma capsulatum were analyzed by single and tandem two-dimensional immunoelectrophoresis (TD-IEP) using a rabbit hyperimmune anti-histoplasmin polyvalent serum. Single TD-IEP showed 14 arc precipitates for histoplasmin. Continuity of arcs 2, 6, and 7, and 9 and 10 was observed, suggesting a different polymeric configuration of the same antigen. This was also confirmed in tandem TD-IEP of histoplasmin with homologous (PPC-histo) and heterologous PPC's fromBlastomyces dermatitidis, Paracoccidioides brasiliensis andCoccidioides immitis. Tandem TD-IEP of histoplasmin and PPC-histo displayed a similar antigenic pattern to histoplasmin alone, being arcs 1 and 3 more evident and apparently present only in histoplasmin and PPC-histo. Tandem TD-IEP showed common antigens among the other heterologous fungal purified antigens, and seems useful to observe the multiplicity of antigens present in fungal preparations and to identify those precipitates (arcs 1 and 3) that are predominant in the purified preparation.     

Immunological properties of an artificial antigen possessing the specificity of Salmonella O-factor 3

For the first time the method of obtaining synthetic protein-free antigen with the specificity of Salmonella O-factor by the radical copolymerization of the synthetic trisaccharide 3-0 [4-0-(beta-D-mannopyranosyl)-alpha-L-rhamnopyranosyl]-beta-allyl-D- galactopyranoside with acrylamide was developed. The synthetic antigen thus obtained possessed the narrow specificity of serogroup E Salmonella O-factor 3. The serological activity of the antigen, studied in the precipitation and passive hemagglutination tests, was considerably higher than that of lipopolysaccharides isolated from S. anatum and S. newington. This synthetic antigen proved to be nontoxic and possessed immunogenic properties, inducing the formation of antibodies to Salmonella O-factor 3 in immunized animals.     

Immunological and functional aspects of H-Y antigen

Summary Male-specific H-Y antigen may be defined by graft rejection, killer cell action or antibodies. Most commonly H-Y antigen is detected in assays using H-Y antisera. In these tests errors may arise from various causes: 1) Auto- and heteroantibodies cross-reacting with target cells. 2) Restriction phenomena. 3) MHC-dependent modification of the amount of H-Y antigen present on different tissues. 4) Modification of cell surface antigens by bacteria or viruses.Regarding the third definition of H-Y antigen, four different states can be distinguished in the mammalian male. H-Y occurs (1) as an integral part of the plasma membrane; (2) unspecifically attached to the membrane of human erythrocytes; (3) free in solution; (4) bound to its gonad-specific receptor.Redistribution experiments suggest that H-Y and ₂-m are associated on the cell membrane. Coredistribution is not found of H-Y and MHC antigens. An antibody blocking technique demonstrates association of H-Y and H-2D antigens on unfixed lymphoid, but not on testicular cells. Human erythrocytes lacking ₂-m do not integrate H-Y antigen into the cell membrane. Male erythrocytes, however, absorb H-Y antigen from the serum. The origin of H-Y antigen in the serum is not clear. It may be shed from cell membranes, derive from the testis which actively secretes H-Y antigen, or both.H-Y antigen is bound by a gonad-specific receptor. This receptor is present in the gonads of both sexes. H-Y antigen is supposed to mediate testis differentiation via this receptor. Reaggregation experiments in vitro using dissociated gonads of the newborn rat demonstrate that ovarian cells reorganize into testicular structures in the presence of H-Y antigen. The assumption cannot be confirmed that addition of H-Y antiserum to testicular cells results in ovarian structures. This finding, however, does not conflict with the view that H-Y antigen is involved in testis differentiation, e.g. by inducing testis cell-specific functions via the gonad-specific receptor.