Characterization of in vitro differentiated secondary lymphocytes : Quantitative and ultrastructural study

Blast cells derived from rat lymphocytes by stimulation with concanavalin A (ConA) or pokeweed mitogen (PWM), or by sensitization on xenogeneic fibroblast monolayers, transformed into secondary small lymphocytes following their transfer to syngeneic monolayers devoid of mitogen or sensitizing antigen. This transformation resulted in the disappearance of morphological blast characteristics such as euchromatic nuclei, prominent nucleoli and the aggregation of ribosomes into polysomes. Secondary lymphocytes resembled non-stimulated cells, but differed from them in possessing a slightly larger cytoplasm containing large numbers of lysosomal bodies, interchromatin granules within the nuclei, nucleoli containing homogeneous fine granulo-fibrillar material and a relatively developed Golgi apparatus. Upon re-exposure to the stimulating mitogen or the sensitizing phenotype, the secondary lymphocytes rapidly transformed into blast cells with cytotoxic activity.     

The medium for determining the gelatinase activity of non-fermenting gram-negative microorganisms

To determine the gelatinase activity of Gram-negative nonfermenting microorganisms, a double-layer medium containing 2% of agar in the lower layer and 10-20% of gelatin in the upper layer has been developed. The medium ensures free access of atmospheric oxygen, possibility of rapid (24-42 h) determination of gelatinase activity at 22-25 degrees C, efficacy of the test. simultaneous determination of gelatin hydrolysis by 8-12 strains in one dish.