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[A micro-method for PHA-induced stimulation of human lymphocytes. I. Communication: Technical considerations
Abstract:
A microculture system is described for PHA-induced stimulation of human peripheral lymphocytes. Following purification on Ficoll-Isopaque cells are incubated in microplates (Falcon 3040) for 66 hours in 5% CO2 using PHA-P (Difco) as a stimulant. DNA-synthesis is measured by labelling with 3H-thymidine (spec. act. 400 mCi/mmole) 16 hours prior to the end of the test. Using a multiple automatic sample harvester rapid evaluation is possible. Several variables were analyzed and optimal conditions defined for PHA- and cell-concentration, time dependence, thymidine dosage and buffer capacity of the medium. High variability and otherwise unexplained loss of lymphocyte stimulation in a population of "normal donors" are often due to acute viral infections, especially during the incubation period. On the other hand, source and concentration of serum are of equal importance since sera of healthy individuals differ greatly in their capacity to support PHA-induced stimulation of normal allogeneic lymphocytes. Using pooled or autologous serum we found the reproducibility of the technique to be good. Provided optimal conditions are employed the microtest system described herein should be ideal for in-vitro-analysis of inhibitory or stimulating factors in cancer patients' sera.
Insights
This study details a microculture system for analyzing human lymphocyte stimulation by phytohemagglutinin (PHA). The optimized method ensures reproducible results for evaluating factors affecting lymphocyte responses, crucial for cancer research.
Area of Science:
- Immunology
- Cell Biology
Context:
- Assessing human peripheral lymphocyte response to phytohemagglutinin (PHA) is vital for understanding immune function.
- Existing methods for lymphocyte stimulation assays can be variable and time-consuming.
- Optimizing microculture systems is essential for reliable in vitro diagnostics.
Purpose:
- To describe and optimize a microculture system for PHA-induced human peripheral lymphocyte stimulation.
- To define optimal conditions for cell concentration, incubation time, and stimulant dosage.
- To establish a reproducible method for analyzing factors influencing lymphocyte proliferation.
Summary:
- A microculture system using Ficoll-Isopaque purified human lymphocytes incubated with PHA-P for 66 hours is presented.
- DNA synthesis is measured via 3H-thymidine incorporation, with rapid evaluation facilitated by an automatic sample harvester.
- Optimal conditions for PHA concentration, cell density, incubation duration, thymidine dosage, and serum source were determined, highlighting the impact of viral infections and serum variability on results.
Impact:
- This optimized microtest system provides a reproducible platform for in vitro analysis of immune modulatory factors.
- It is particularly valuable for investigating inhibitory or stimulating factors in cancer patients' sera.
- The findings contribute to the development of more accurate diagnostic and prognostic tools in oncology and immunology.