Final answer:
In indirect immunofluorescence, both positive and negative controls are necessary to validate the results. Positive controls confirm protocol efficacy and specificity, while negative controls ensure that any observed fluorescence is not due to nonspecific binding or autofluorescence.
Step-by-step explanation:
In indirect immunofluorescence, appropriate controls are essential to validate the results. The correct answer to the question is a) Positive and negative controls. Positive controls are used to confirm that the protocol works and the fluorescence signal is due to the antigen of interest. Negative controls, which do not contain the primary antibody or the antigen, are required to ensure that any fluorescence is specific and not due to nonspecific binding or autofluorescence of the sample.
Positive controls typically involve using a sample known to contain the antigen or employing an antibody with a known reactivity. Negative controls may include omitting the primary antibody, using an irrelevant primary antibody, or using a sample known not to contain the target antigen.
Running both types of controls allows the researcher to interpret the results with confidence knowing that the observed fluorescence is specific to the antigen-antibody reaction and not a result of artifacts. Therefore, to make correct interpretations in indirect immunofluorescence, positive and negative controls are necessary.