Previous reports (1, 2) have described a system in which a culture of lymph node cells from non-immunized rats was stimulated, in vitro, to produce specific antibody. This stimulus was provided by a cell-free homogenate of peritoneal exudate ceils, consisting mainly of macrophages, which had been incubated with the antigen in question. The observations that both streptomycin and ribonuclease rendered the system ineffective directed attention to the possibility that nucleic acid was an essential factor. The experiments to be presented show that the specific stimulatory activity resides in a purified ribonucleic acid fraction of the cell-free homogenate.Tests for activity of the purified material were conducted with the aid of diffusion chambers. Such chambers, charged with non-immune rat lymph node ceils and the material to be tested, were inserted intraperitoneally into x-irradiated rats. In some experiments the material alone was placed into the chambers which were then inserted into non-irradiated recipients. Activity was measured by titrating the sera of the recipient rats for specific antibody. Material and MethodsAnimals.--200 to 250 gm Wistar rats were used as recipients for the diffusion chambers, and as the source of exudate cells, hereafter referred to as macrophages. 60 to 80 gm rats served as lymph node donors. The procedures for obtaining both macrophages and lymph node cells have been described in a previous paper (2).X-Irradiation Factors.--Rats were exposed to 500 r total body irradiation through the facilities of the Brookhaven National Laboratories. The x-ray factors were 250 KVP, 15 ma, 0.5 mm Cu -4-1.0 mm A1; distance from target to skin, 40 inches; roentgens in air per minute, 28.0. Macrophage-A ntigenInteraction.--The procedure for obtaining sterile cell-free homogenates of macrophage-bacteriophage T2 mixtures has been described (2). In brief, the macrophages

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A fully automated synthesizer was constructed and designed to perform high speed miniaturized syntheses of compound libraries using the SPOT technique. Utilizing magnetically controlled drop-on-demand ink jet nozzles, an r/phi array format of 2500 spots can be simultaneously dispensed from up to 24 separate reagent valves onto a rotating disc as the solid phase in less than three minutes. In addition, a complete wash station is on board allowing for fully programmable combinatorial syntheses without manual attention. A new carbon black/polypropylene composite solid phase disc was developed and tested for its functionalisation/loading, spot detection, durability and MALDI-TOF target capabilities. The carbon black/polypropylene composite was then successfully employed jointly as the solid phase in the syntheses of short peptide and PNA oligomers and as the target probe holder for MALDI-TOF measurement without transfer of the material. Several protocols for PNA syntheses were also investigated and an optimised PNA methodology for the carbon black/polypropylene composite is reported.

The RNA extracted from normal peritoneal macrophages exposed to a linear, random synthetic polypeptide, Glu(60)Ala(30)Tyr(10), initiated an immune response in C57B1/6J mice, although this strain responds very poorly to the antigen itself. From 10 to 150 micrograms of RNA obtained from mouse, rat, or rabbit macrophages was injected intraperitoneally into recipient mice, and specific antibody was detectable by passive hemagglutination 3 to 4 weeks later. Treatment of the RNA with ribonuclease destroyed its ability to initiate a specific immune response. The RNA contained by weight 0.02 percent of the (specific) antigen. The RNA obtained from cells incubated with a second polypeptide, Glu(36)Lys(24)Ala(40), initiated a response specific for this polymer. This RNA even when incubated in vitro with Glu(60)Ala(30)Tyr(10) failed to initiate antibody formation specific for Glu(60)Ala(30)Tyr(10).

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This study was designed to determine whether natural immune responses could elicit immunoregulatory auto-antiidiotypic antibodies. Female rabbits heterozygous at the a and b Ig loci were bred to homozygous males. Offspring of one such breeding were studied for natural production of antibodies specific for the noninherited allotypes and for the production of immunoregulatory auto-antiidiotypic antibodies. All offspring mounted natural antiallotype responses. The anti-a1 responses cycled as a function of time whereas the anti-b5 responses were invariant. Anti-a1 responses from two offspring were shown to change specificity for different a1 subsets as they cycled. Anti-a1 was purified from the first cycle and was used to assay for auto-antiidiotypic responses. Auto-antiidiotypic antibodies were detected and were found to cycle in an inverse way with the anti-a1 cycles. The idiotopes detected using the natural auto-antiidiotypic antisera were strongly cross-reactive. Subsequent deliberate immunization showed that antibodies specific for all a1 subsets could be elicited after auto-antiidiotypic regulation had functioned. The data support the interpretation that idiotype network interactions indeed function in naturally occurring immunologic situations and are not merely laboratory curiosities or artifacts.

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