Chemical markers of transplantation individuality solubilized with sonic energy

Solubilization of human sperm antigens

Various methods of solubilization of human sperm antigens were compared by testing the sperm extracts against rabbit antihuman spermatozoa immune serums with double immunodiffusion and rocket immunoelectrophoresis. Marked differences were found in the protein contents and the SDS-PAGE protein patterns of the extracts. Lithium diiodosalicylate was the most efficient in solubilizing the sperm proteins and in preserving their antigenicity. Nonionic detergents also gave, either alone or combined to sonification and 1.0 M KCl, 24-28 clearly discernible protein bands and several different immunoprecipitates. Ionic detergents deoxycholate and cetylpyridinium chloride solubilized a high yield of proteins, but their antigenity was poor.

Purification of tumor-specific antigens. An overview of the relevance to human colon carcinoma

Methods which dissociate intramolecular noncovalent bonds have been used to prepare soluble derivatives of cell-surface antigens. Applications of these techniques to human colon carcinoma are underway. Continuous tissue-culture strains derived from primary lesions were developed and shown to be composed of malignant epithelial elements. Parallel data on the preparation and activity of soluble materials in a murine model methylcholanthrene system reveal that although cultured cells are a satisfactory source for antigen extraction, they are poor targets of the immune response. The development of methods to quantitate the biologic activity of colon-specific, soluble materials may provide indicator systems to define the antigenic determinants, to permit purification, and to serve as assays of the efficacy of immunotherapy.

Rat transplantation antigens. I. Extraction and partial purification of a soluble antigen

A soluble histocompatibility antigen was extracted from normal rat lymphoid cells by exposure to an hypertonic KCl solution. The antigen was assayed by inhibition of monospecific cytotoxic (CT) alloantiserum and shown to have the specificity AgB 4 or Rt H1.1, the major locus private antigen of the dark agouti strain. Yields were ~2000 CT inhibitory units (ID₅₀) per 10⁹ cells. Gel filtration of the extract over Sephadex G-200 resulted in an approximate four-fold purification with a final concentration of 530 ID₅₀ units per mg protein. The major portion of the antigen appeared at the front of the inner bed volume but a minor included peak at about 65,000 mol wt. was also seen. Yields and specificity were greatly increased by (a) not washing the cell suspension before extraction (b) removing excess salt from the extract by dialysis rather than gel filtration (c) removing insoluble nucleic acids from the dialysed extract by ultracentrifugation.

Occurrence of a theta-like antigen in rats

A rat antigen system parallel to the mouse theta system has been described(*) All rat strains tested expressed an antigen cross-reactive with the theta-AKR specificity of mice while none cross-reacted strongly with theta-C3H. The rat antigen may be demonstrated by either absorption or direct complement-mediated killing of rat thymocytes. Patterns of organ distribution and developmental appearance in the nervous system of rats also parallel those previously reported for theta in mice.

Salt extraction of soluble HL-A antigens

Extraction of cultured human lymphoid cells with hypertonic salt solutions (3 molar potassium chloride) resulted in high recoveries of membrane-associated histocompatibility (HL-A) antigens in soluble form with potent activity and marked immunologic specificity. The active principle was purified by preparative acrylamide-gel electrophoresis. Application of the hypertonic salt extraction method is now yielding sufficient HL-A antigen to begin the elucidation of the molecular basis of transplantation individuality.