title: Studies on the thermal degradation of the H and M antigens of lyophilized histoplasmin.
abstract: Lyophilized histoplasmin for the agar gel microimmunodiffusion test has been prepared as a candidate World Health Organization Biological Reference Reagent. It was subjected to elevated temperature for given periods of time and analyzed by the capillary precipitin test and the single radial immunodiffusion test to determine the stability of the H and M antigens. H antigen showed no fall in relative potency when incubated at 48 degrees C for 20 days. M antigen showed a fall in relative potency after storage at 37 degrees C and 48 degrees C, but the extent of the fall was greater in the radial immunodiffusion test than in the capillary precipitin test. Half-lives of the antigens could not be calculated from the Arrhenius equation because the response curves at each temperature followed different kinetics. However, as based on zero time data, M antigen of the lyophilized histoplasma showed a 20% drop in relative potency when stored at -20 degrees C for 2 years. Other analyses suggested that M antigen of liquid histoplasmin stored at 5 degrees C and of lyophilized histoplasma stored at -20 degrees C was degraded at equal rates.
mesh_terms: D000818:Animals; D000939:Epitopes / Q000276:immunology*; D005612:Freeze Drying; D006207:Half-Life; D006659:Histoplasmin / Q000276:immunology* / Q000592:standards; D006358:Hot Temperature; D005779:Immunodiffusion; D011233:Precipitin Tests; D011489:Protein Denaturation; D011817:Rabbits
chemical_list: D000939:Epitopes; D006659:Histoplasmin