Final answer:
The correct answer is B: in a one-way mixed lymphocyte culture, lymphocytes from one subject are prevented from proliferating by pretreatment with radiation or mitomycin. This setup allows for the measurement of the immune response of the other subject's lymphocytes.
Step-by-step explanation:
The question relates to a one-way mixed lymphocyte culture (MLC), which is a method used in immunology to measure lymphocyte function and is often used as a test for Histocompatibility or immune response. Answer B is the correct response. In a one-way MLC, lymphocytes from one subject are indeed prevented from proliferating to ensure that only the response of the lymphocytes from the other subject is measured. This is typically accomplished by irradiating or treating one set of lymphocytes with mitomycin C, which inhibits their DNA synthesis and thereby their proliferation. This allows the non-treated lymphocytes to react against the antigens presented by the treated (and hence non-proliferating) cells, simulating an organ transplant scenario at a cellular level.
As far as the other options are concerned, the uptake of tritiated thymidine (³H-thymidine) would increase, not decrease, because this radioactive compound is incorporated into dividing cells' DNA, which reflects lymphocyte proliferation. Therefore, option A is incorrect. Option C is incorrect because histocompatible lymphocytes, meaning those with a similar or compatible set of histocompatibility antigens, would typically not stimulate each other's proliferation in a one-way MLC because they are seen as 'self.' Furthermore, option D is incorrect as lymphocyte proliferation in a mixed lymphocyte culture is typically measured after several days, not just a few hours since cell division and the immune response take time to occur.