👉Adhesion mediated by CR3 & CR4.
👉Oposonization mediated by CR1 & CR3.

1-Tickover activation
active in HEALTHY people.
2- Membrane bound cascade active only in INFECTED people.

👉mannose-binding lectin (MBL) is a protein produced by hepatocytes .

👉MAC Affect more gram NEGATIVE bacteria.

👉CR1 affect more grame POSITIVE bacteria.

👉Lysozymes affect more gram POSITIVE bacteria.

👉Defensins affect both gram POSITIVE & NEGATIVE bacteria.

👉Why the RNase & protein kinase which produced by type 1 interferon (secreted by virus infected cells) don't degrade our RNA & proteins in cells which are not yet infected?

👉Because they are secreted as inactive but they will be active by presence of virus ➡ degradation of our &virus RNA 😔.

Acute phase proteins (Binding proteins)

They are synthesized by liver cells in response to IL-6 , lL-1 &TNF.

👉Why Defensins degrade microbial cells but not our cells?

👉Because Defensins inhibited by presence of cholesterol on our cells which not present on microbes.

👉Why lysozymes degrade microbial cells but not our cells?

👉Because Lysozyme degrades the peptidoglycan layer in the bacterial cell wall which not found in our cells.

👉Why broad spectrum antibiotics which kill normal flora lead to increase bacterial infection?

👉Due to 1- increase the attachment site for pathogenic bacteria which was occupied by normal flora.
2- Decrease of monolactam & colicins which was secreted by normal flora to kill pathogenic bacteria.

👉Bacteria which can invade the intact skin is Bacteria which cause syphilis ( trypanosoma pallidum) .

Why there is a decrease in immune response in pregnancy?

حتى لا يحدث rejection of baby.

Why Vaccines are given IM, SC, oral but not IV ?

Because a given dose of antigen may elicit no detectable response when injected intravenously but may elicit a strong immune response if injected intradermally or subcutaneously due to
● Slow removal of the antigen ➡ increase the contact between antigen & immune system .
● Presence of antigen-presenting cells (APCs).

👉Why we prefer Vaccines with adjuvants ?

👉Because Adjuvants are agents which when administered along with an antigen enhance the specific immune response.

👉CD35 (CR1) is a membrane bound co-factor which inhibit complement formation on human cells .

👉CD55 is a decay-accelerating factor which inhibit complement formation on human cells but not microbes .

👉CD59 is The major membrane inhibitor of MAC formation on human cells by inhibition of C9 polymerization.

All of them found on human cells but not microbes.

👉CD56 is a receptor present on the surface of Natural Killer cells (NK cells).

Why MHC class ll Closed by invariant chain ?

عشان يمنع ارتباطه ب ال intracellular pathogens.
لانه وظيفته يرتبط ب ال extracellular pathogens.

👉B cells , macrophages & Dendritic cells are called professional cells what the deference between them ?

👉B cells is specific (every cell against one microbe).
👉macrophages & Dendritic cells are non specific.

👉If microbe enter to our body lead to formation of polyclonal or monoclonal antibodies?

👉Polyclonal antibodies because microbe has multiple epitopes (antigen determinants ).

👉What the classes or types of cell adhesion molecules (CAMs) ?

👉They are 2 types selectins and integrins.

👉Selectins :- 1- L-selectin is expressed on leukocytes .
2- E-selectin and P-selectin are expressed on the endothelial cells.

👉Integrins :- 1- leukocyte function-associated antigen 1
(LFA-1) and the very late antigen 4 (VLA-4). Both are expressed on leukocytes.
2- intercellular adhesion molecule 1 and 2 (ICAM-1, ICAM-2), vascular cell adhesion molecule 1 (VCAM-1) are
proteins expressed on activated endothelial cells.

👉Neutrophils &macrophages both are phagocytic cells what the deference between there phagocytosis?

👉Neutrophils destruct and release all the digested product while macrophages destruct and release some of the digested product and the other well presented by MHC class II for T helper cells CD4.

👉Neutrophils take antigens to lymph node to B lymphocyte lead to production of antibodies.

NK cells have 3 receptors :-
lgG , activating &inhibitory Receptors.

👉Specific immunity can recognize many antigens (due to many cells) but one cell recognize only one antigen.

Many different cells due to many different receptors because the sequence of these protein receptors is extremely diverse.

One cell = One specificity.
لانه كل خلية من ال T cell تتعرف على one antigen.