Question XIV. Consider each numbered statement (190-194) as a completely indepen

Question

Question XIV. Consider each numbered statement (190-194) as a completely independent assertion. Using your current knowledge and basic rules of formal and informal logic, please, assess the following statements as factually correct (true) or incorrect (false):

190. Peripheral tolerance is caused by co-stimulation without TCR-MHC peptide interaction.
191. Peripheral tolerance is caused by TCR-MHC peptide interaction without co-stimulation.
192. Peripheral tolerance does not lead to anergy.
193. Nonresponsiveness as a result of peripheral tolerance cannot be reversed.
194. The mechanisms of autoimmune diseases include a failure of central tolerance.

Explanation / Answer

Peripheral tolerance is the mechanism which provides immunity to the self tissues of a human against attack by its own lymphocytes. T-Lymphocytes have receptors known as TCR which are responsible for recognising foreign antigens in the body. It is crucial that these TCR should know the difference between self and non-self tissues. T-cells with higher affinity for Self tissues or self MHC molecules, it can lead to potential harmful autoimmune disease which may damage the internal organs. By “peripheral”, it means outside the thymus.

Peripheral tolerance is the event when TCR of T-cells and MHC peptides interact with each other but there is no stimulation of receptors and T-cells do not get activated. So option 190 is FALSE as there is no stimulation. And option 191 is TRUE.

Anergy is the state of body where body becomes unresponsive towards a potential pathogen or foreign antigen because of the peripheral tolerance property of the T-cell. T-cells fails to recognize the antigens. Hence, option 192 is FALSE. Because peripheral tolerance may lead to anergy.

Non-responsive as a result of peripheral tolerance can be reversed during some pathological conditions. Hence, option 193 is FALSE.

Autoimmune diseases happen when the T-cells recognize and get activated by self MHC molecules. This may be genetic and hence caused by the failure of central tolerance mechanism. Hence, option 194 is TRUE.

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