Question

a.) During heat sterilization, what is the decimal reduction time?

b.) Are TLR (toll-like receptors) part of the innate or adaptive response? Describe their function.

c.) Describe the Humoral Immune response and the overall outcome.

Answer 1

a)Heat sterilisation of an article is one of the earliest forms of sterilisation where hot air that is either free from water vapours or has very little of it ,are used for sterilisation.

During heat sterilisation decimal reduction time or decimal reduction dose is the time or dose required at a given condition e,g temperature or set of conditions to kill 90%(or 1log) of the exposed micro_organisms.

b)Toll like receptors (TLR) are a class of proteins that play a key role in the innate immune system.They are single ,membrane _spanning,non_catalytic receptors usually expressed on sentinel cells such as macrophages and dendritic cells ,that recognise structurally conserved molecules deceived from microbes.

Functions of TLR:_

The ability of immune system to recognise molecules that are broadly shared by pathogens is ,in part ,due to the presence of immune receptors called toll like receptors that are expressed on the membrane of leukocytes including dendritic cells ,macrophages natural killer cells ,cells of adaptive immunity (T and B lymphocytes) and non_immune cells epithelial and endothelial cells and fibroblasts.

The binding of ligands either in the form of adjuvant used in vaccinations or in the form of invasive moieties during times of natural infection _to the TLR marks the key molecular events that ultimately lead to innate immune responses and the development of antigen specific acquired immunity .

Upon activation ,TLR's recruit adapter proteins within cytosol of immune cell in order to propagate the antigen_induced signal transduction pathway.These recruited proteins are then responsible for subsequent activation of other downstream proteins including protein kinases that further amplify the signal and ultimately lead to suppression of genes that causes inflammatory responses and other transcriptional events .TLR's have also been shown to be an important link between innate and adaptive immunity through their presence in dendritic cells.

c)Humoral immune response involves the humor or body fluids .It protects the extracellular space within the body by circulating the antibodies ,complement proteins or antimicrobial peptides to destruct the circulating virus ,bacteria,or other infectious agents.The components involved in the humoral response are B_cells ,T_helper cells (TH1/TH2),interleukins, cytokinesis and antibodies .Following are the important steps involved in humoral immune response:

1) Binding of antigens by B_cells .

2)Activation of B_cells by helper T cells_ either TH1 or TH2 dependent ,with majority being TH2 dependent.

3)B_cell proliferation to produce plasma cells containing antibodies specific to antigens .

4)Circulation and secretion of antibodies.

5) Binding of antigen and antibody and neutralisation of antigen.

6)Production of memory B_cells.